The IT Blog

Format or unlock a password/pattern locked Android phone

2013-05-10T14:43:00.001+05:30

Do you you want to format your Android phone using the hard reset method?
Some of the things that will make you format your device this way includes:

If the device owner forgot the unlock pattern or pin of his/her Android phone.
Once you forget this code, you cannot access the contents of your device unless the unlock screen gets out of the way. The last recommended solution to this is to wipe the data of your phone without accessing the menu. Note that this will erase all your personal files, info and apps in the phone storage. You will only

regain this if you earlier on backed up your phone on your local drive or Google account. This procedure will leave your SD card untouched.

If you want to free system memory.

Formatting of device and a manual reinstallation of apps will remarkably yield free memory for use.

Restore phone to factory setting.
This is needful if you want to sell your phone or if a change in a system file made your phone to malfunction.

HOW TO FORMAT/HARD RESET A LOCKED ANDROID PHONE.
Its simple. Many Android phone makers gives a specific guideline on this but in the absence of such, generally you:

1. Switch off the device
2. Hold the POWER key together with at least the down volume key to power the phone and start the resetting process.
3. A command-like window with sometimes a green text appears
4. Use the up/down arrow key to scroll screen and use the Power key to select.
5. Select WIPE DATA and the phone reboots after some few minutes to

How to Wipe Your Android Phone

2013-05-10T14:30:00.001+05:30

If you've got to return your fancy Android phone for some reason, or you plan to sell your older model on eBay, you'll want to make sure your private information is thoroughly cleaned from the device. Setting your Android phone back to its factory defaults is simple enough, but ensuring your phone is completely clear is a two-step process. First, you need to format your microSD card: Under 'Settings,' tap the entry for 'SD Card and Phone Storage.' From here you'll need to unmount and then format your SD card (both options are clearly labeled). After that, go back out to the main settings menu and tap the 'Privacy' option. Under that menu you'll find an option for 'Factory Data Reset.' This will return the phone to the state it was in when you first took it out of the box.

Android apps coming to an AMD-powered PC near you

2012-10-02T12:33:00.003+05:30

The BlueStacks App Player will allow users to run Android apps on their AMD-powered Windows PCs, including those running Windows 8

A new partnership between virtual Android specialist BlueStacks and microchip maker AMD will see much of the Google Play store's stock of apps made available to Windows users running AMD hardware, the company announced Thursday.

Users wishing to run Android apps on their AMD-powered Windows PCs -- including those running Windows 8 -- will be able to use the free BlueStacks App Player program to do just that. AMD's AppZone store can also be used with BlueStacks' Cloud Connect system, letting users sync Android apps from their phones or tablets to an AMD device.

"By collaborating with BlueStacks, we are enabling software developers to more easily tap into the full capabilities of AMD's products, and providing millions of consumers with great experiences as they can now run Android apps on AMD-powered devices," Manju Hegde, corporate vice president of heterogeneous applications and developer solutions, said in a statement.

Android apps run through the AppZone will take advantage of AMD's graphics acceleration technology -- either in the form of a discrete graphics card or the company's integrated accelerated processing units.
AMD is also working to convince OEMs to ship products with the AppZone pre-loaded, offering baked-in Android functionality to its devices.

BlueStacks first rolled out the App Player in 2011, and ported the functionality to OS X this July, giving Mac users the unusual option of running Android software on an Apple product. The company's Cloud Connect sync application has been downloaded more than 100,000 times from the Play store, and the new integration with AMD could see that number increase substantially.

MySQL users caution against NoSQL fad

2012-10-02T12:30:00.001+05:30

At Oracle's MySQL Connect conference, users question the need for NoSQL technologies

While NoSQL may be getting all the buzz, in many cases an old fashioned relational database, such as MySQL, may work just as well if not better. That was the message from a number of MySQL users who presented their stories at Oracle's first MySQL Connect conference, held Saturday and Sunday in San Francisco.

On Sunday, engineers and executives from Twitter, PayPal and Verizon discussed their use of MySQL or MySQL Cluster. In each case, MySQL was being used for large high volume, distributed workloads that have been increasingly thought of as the province of NoSQL data stores such as MongoDB and Cassandra.

"A lot of people think they have a big data problem, and a lot of times they don't," said Daniel Austin, who is the chief architect for PayPal. "They have an urge to find a big data solution to a problem, because it looks good."

Austin admits that the typical relational database system (RDMS) architecture has not scaled very well to meet the influx of new data in many organizations, but he cast doubt on the idea that NoSQL data stores provide the answer. "You don't have to give up your relational model to have big data," Austin said.
Paypal itself deals with large amounts of data for its global payment transaction system, which must be fast and accurate. The system must be able to manage 100TB of fixed storage, and once data is written to the system, it must be able to be read from anywhere else in the world in less than a single second. This can be a challenge given that the fastest data can travel between the two most distant places on earth is about 67 milliseconds, thanks to the hard limit of the speed of light. "So that puts a lower bound of how fast things can go," Austin said. The company uses Amazon Web Services, spread across six different locations. All the live data is handled in-memory, rather than being immediately written to disk.

PayPal uses MySQL Cluster for a number of reasons, most notably that true High Availability (HA), which ensures that all the data entered into the system is captured immediately. Another advantage MySQL Cluster offered was scalability.

"We had to think about how to build the architecture a little bit," Austin said. The approach they used, called architectural tiling, was designed to "build a system that scales to an arbitrary number of users. And we did that with SQL," Austin said. " We feel confident we can scale beyond 100 million users no problem."
Another big user of MySQL is Twitter. Currently, Twitter has over 140 million active users, who issue about 400 million Twitter messages every day, all of which have to be stored, indexed and annotated with metadata. The company uses a modified version of MySQL 5.5 to handle this load. The company has six full time database administrators, to maintain "a few thousand database servers," said Jeremy Cole, the chief database architect for Twitter. The company also employs one full-time MySQL developer.
Cole spoke to why Twitter uses MySQL even when NoSQL databases would seemingly be better suited for such a heavy workload. "It comes down to a few key points," Cole said.
One is basic familiarity. "We have very extensive at-scale knowledge. We know how MySQL works internally. We know how to upgrade it, we know how to fix bugs and push out new releases," Cole said.

The company also appreciates MySQL's performance. With a bit of tuning, most of Twitter's MySQL servers are running "tens of thousands of queries per second," Cole said. The latency of the queries must be in the level of micro-seconds. Cole said that he will get pitches from NoSQL vendors making claims that NoSQL is faster than a relational SQL database. "Often that is not true," Cole said.
Data safety is another crucial component for Twitter. Twitter's internal database engine, InnoDB "does not lose our data," Cole said. Another advantage includes a strong ecosystem, including support and development from companies like Oracle and Percona.

While the company uses MySQL for many things, it also uses other data storage technologies for those cases where MySQL won't fit. For instance, the company developed a sharding and replication software, called Gizzard, that runs on top of MySQL. "I prefer to treat MySQL as a building block -- use it as a really strong core of features that we understand, and build solutions on top of that core," Cole said.

The online gaming company Playful Play was another customer that testified about its success of high-volume MySQL usage. This Mexico-based online game company recently found itself with a huge hit on its hands. The company's "La Vecindad de El Chavo," based on the popular long-running Mexican comedy series "El Chavo," has attracted over 3 million users since its launch in March, a number that is growing by 30,000 subscribers daily. "We had 100,000 in the first day and we got very scared. We didn't know what we had on our hands," said Ricardo Rocha, Playful Play CEO.

The company initially used the free version of MySQL Cluster, but when traffic suddenly spiked so that their need for servers exceeded Oracle's free licensing, the company contracted with Oracle for support. In fact the growth of traffic was so sudden that when the company experienced performance issues and Oracle flew support personnel to the company's headquarters before the support contract was actually signed.

Today the company runs MySQL Cluster Carrier Grade Edition across 24 servers, to capture data on user and avatar profiles, as well as play and advertising data. Twelve are for production, and the rest are for marketing analysis, pre-production and load-balancing.

The company is currently expanding its infrastructure to support as many as 100 million users, as part of its plans to expand to through Latin America, as well as Turkey, Spain, the Philippines, and Malaysia, countries where the show is also aired.

Source : infoworld

InfoWorld Home / Data Management / News / Oracle sheds more light on database 12c, Exadata... 3 0 0 Submit 0 Click here to find out more! October 01, 2012 Oracle sheds more light on database 12c, Exadata X3

2012-10-02T12:26:00.002+05:30

'Pluggable' databases and massive in-memory storage are the key features of the new products

Oracle on Monday gave attendees of the OpenWorld conference in San Francisco a deeper look at its new 12c database and Exadata X3 machine, which were initially announced Sunday by CEO Larry Ellison .
The key feature of 12c, which is set for release sometime next year, is multitenancy, which enables users, if they desire, to create multiple "pluggable" databases that reside within a single database container, senior vice president Andy Mendelsohn said during a keynote address.

This constitutes "a fundamental re-architecture of the database," Mendelsohn added. "Now if I'm an administrator, I have one database overall to administer."
The pluggable database concept is "sort of like a Swiss Army knife," giving DBAs a flexible tool to run their environments, he said, noting that Database 12c also makes much more efficient use of hardware resources, saving companies money. For example, it incorporates a "heat map" feature that tracks how frequently different chunks of data are used, allowing customers to archive rarely accessed information on lower-cost mediums.
Database upgrades and patches are made simpler than in the past thanks to the pluggable database concept, Mendelsohn said. "When you [patch] that one container database, you effectively patch all of them."
Backup and recovery efforts benefit as well, allowing administrators to back up the system as one unit but recover at the pluggable database level.
Pluggable databases are also ideal for creating development and test environments, and are "perfect" for SaaS (software as a service) applications since they keep each customer's data private, Mendelsohn said.
"Each one of these pluggable databases is an entity that stands alone. It has all its own metadata and private data files," and as a result can be moved easily from one database system to another, Mendelsohn added in a follow-up session.
One key question Mendelsohn left unanswered was whether the multitenancy features will mean changes to Oracle's licensing model for the database; currently customers pay according to the number of processors the software runs on.
Prior to Mendelsohn's appearance, Oracle senior vice president Juan Loaiza took the stage to provide more details of the next-generation Exadata X3 database machine, which Ellison also announced Sunday.
The X3 systems contain large amounts of DRAM and flash cache, allowing data to be held in-memory versus read off disks, increasing performance dramatically, according to Oracle.
Loaiza also provided a sense of the market uptake for Exadata, which was first introduced in 2008.
There are now "thousands of deployed systems," ranging from petabyte-scale data warehouses to ones running transactional business applications from Oracle and SAP, he said. About half of the Exadata installed base to date is using it for data warehousing, with the other half running OLTP (online transaction processing) workloads, according to Loaiza.
He also sought to show audience members that Exadata is relatively easy to deploy, bringing on an executive from PayPal who described how the company took its Exadata from a pilot project to a "business decision platform" in just 60 days.

X3 systems are available now for use with any application certified for Oracle Database 11g R2 and Real Application Clusters, according to a statement. They are also "fully compatible" with previous Exadata versions, allowing customers to upgrade to X3, Oracle said. Hardware pricing is the same as the previous generation but that doesn't account for the large amounts of separately licensed Oracle software the systems run.
They are available in full, half, quarter and eighth-rack configurations, with the last being a new option aimed at smaller companies.
Loaiza's remarks avoided competitive trash talk of the kind Ellison dished out on Sunday when unveiling X3. In particular, Ellison singled out rival SAP's HANA in-memory database platform, calling its capacity "very small" in contrast to Exadata X3.
Ellison's remarks were "misleading to customers" and "completely false," SAP executive board member and technology chief Vishal Sikka said in an interview Monday.
SAP has created a 100TB HANA system using only DRAM and could upgrade it to 250TB if it desired, Sikka added.
SAP may discuss HANA's competitive positioning against Exadata further during its Tech Ed conference later this month.

Source : infoworld

Facebook Posts Its Internal C++ Software Library

2012-06-06T16:51:00.002+05:30

Facebook has released a library of C++ software components used to help run its site, the social networking company announced Saturday.

"One clear bottleneck to releasing more work has been that any open sourced project needed to break dependencies on unreleased internal library code," wrote Facebook software engineer Jordan DeLong, who posted an entry on Facebook announcing the release.By releasing this library, called Folly, Facebook will be able to release more of its internal programs as open source, because they rely on different components in this library.

Facebook engineers also announced the release at a C++ conference the company is holding Saturday at its campus at Menlo Park, California.

Facebook has relied on open-source software, such as MySQL, PHP and memcached, to run its sites. And so the company has made a point of releasing its own internal programs as open-source software as well, such as the HipHop PHP compiler and the Thrift service sharing framework.

For many of its open source releases though, Facebook developers have had to rewrite some of the functionality that was borrowed from this library. By releasing the library itself, Facebook will be able to "continue open sourcing parts of [its] stack without resorting to reinventing ... internal wheels," DeLong wrote.

Even if developers don't plan on using Facebook developed applications, they should still take a look at this library, as it includes many utilities of possible to use in other environments, DeLong said. Many of the components available in Folly run more quickly than their equivalents available elsewhere, he boasted. "Our motivation was to build components that were faster and more efficient than what we previously used," he wrote. These utilities were designed to be used in heavy production environments, across thousands of servers.

The components cover a range of functionality. One component was designed to use memory more efficiently. Another reduces contention. The AtomicHashMap utility cuts the amount of time a piece of data in memory is locked by an operation, which can slow performance and cause bottlenecks in heavily used environments. A set of string manipulation components use fewer CPU cycles than formatters in other C++ libraries, DeLong boasted.

The Folly library is posted on GitHub, and Facebook will add new components as they are written, according to DeLong.

How To Tell If A Link Is Safe Without Clicking On It

2012-06-06T15:58:00.001+05:30

Even the best security software can’t protect you from the headaches you’ll encounter if you click an unsafe link. Unsafe links appear to be shortcuts to funny videos, shocking news stories, awesome deals, or “Like” buttons, but are really designed to steal your personal information or hijack your computer. Your friends can unknowingly pass on unsafe links in emails, Facebook posts, and instant messages. You’ll also encounter unsafe links in website ads and search results. Use these link-scanning tips to check suspicious links. All of these solutions are free, fast, and don’t require you to download anything.

Hover Over the LinkSometimes a link masks the website to which it links. If you hover over a link without clicking it, you’ll notice the full URL of the link’s destination in a lower corner of your browser. For example, both of these links connect you to PCWorld India’s home page, but you wouldn’t know that without hovering:

Click Here!

http://www.freerolexwatches.com/

Use a Link ScannerLink scanners are websites and plug-ins that allow you to enter the URL of a suspicious link and check it for safety. There are many free and reliable link scanners available; I suggest you try URLVoid first. URLVoid scans a link using multiple services, such as Google, MyWOT, and Norton SafeWeb, and reports the results to you quickly.

URLVoid scans several security databases for information on sketchy Web domain names.
Check Out Shortened LinksURLVoid can’t properly handle shortened URLs from services such as bitly, Ow.ly, and TinyURL (URLVoid will scan the shortening service website instead of the link to which it points). To scan the mysterious shortlinks you’ll often find on Twitter and Facebook, use Sucuri. Sucuri automatically expands the shortlink and draws upon a handful of services, such as Google, Norton SafeWeb, and PhishTank, to determine if the real link is safe. You can also use Sucuri for scanning nonshortened links, but URLVoid checks more sources.

Sucuri can help you determine whether shortened links are safe or not.
Copy a Link--SafelyServices like URLVoid and Sucuri require you to type in or paste a suspicious link—but how do you quickly and safely grab the URL without opening anything? Easy. Just right-click the link to bring up a context menu, then click Copy shortcut (in Internet Explorer), Copy Link Location (in Firefox), or Copy Link Address (in Chrome). The URL is now copied to your clipboard and you can paste it into any search field.

Windows 7: Back Up And Restore Data

2012-06-06T15:48:00.001+05:30

Back Up And Restore Data With Windows 7

Backing up your files is one of the most important things you can do to safeguard the data you create and store on your computer. To this end, Microsoft included a full backup and restore utility with Windows 7. Here’s how it works.

Backing UpFirst you need to launch Windows' Backup and Restore utility. You will find it in the Control Panel by selecting first System and Security and then Backup and Restore. If you have never used this tool before, you'll see a message under 'Backup' that says 'Windows Backup has not been set up'. Click the link labeled Set up backup to the right of that message.

After the program starts, it will prompt you to choose a location for it to store your backup files in. Windows won't let you choose your main hard drive as a backup drive; so if you haven’t already plugged in your external hard drive, do it now and click Refresh.

After you've chosen the drive that you want to use for your backup, the program will ask you to identify what you want to back up. The default selection is to let Windows choose for you, and create a disk image at the same time. You can be much more selective, however, by clicking the radio button next to Let me choose.

Once you've chosen what you want to back up, and where you want Windows to store it, the program will display a backup summary screen that confirms the options you selected. Before you run your backup, though, you'll probably want to take a look at the default schedule that Windows has set up for you, to confirm that your computer is going to be on at that time of day. If you want to adjust it, click Change schedule and then set it to something more suitable to your schedule.

Finally, click Save settings and run backup. The first backup will be a somewhat lengthy process, but future backups will be quicker, as they will back up only files that have been added or changed since your previous backup.

Restoring From BackupRestoring files from your backup is fairly simple. First, launch the Backup and Restore utility, (as described above); then decide whether to restore all of your files, or just specific files that may have been deleted or become corrupt.

To restore all of your backed-up data, click Restore my files, followed by Browse for folders. Next, on the left side, look for the folder bearing the name of your backup. Click that folder, and then click Add folder. Once you've added the folder to your restore list, click Next and choose whether you want the files restored to the original location or to a new location. Finally, click Restore to bring back all of your data.

To restore specific files, first click Restore my files, and then click Browse for files. Navigate to your backup folder, and choose the individual files that you want. Again, the program will ask you whether you want to restore the files to their original location or to a new location. Once you decide where you want them, click Restore to recover the data you selected.

Unsure about the name of the file you want? Click Restore my files, and then use the Search button to examine your backup for the keywords that you type into the search field. In the search results, locate the files you need, add them to the restore list, and restore them as described above.

Google gives up on mobile Google Docs, buys Quickoffice to go native

2012-06-06T15:26:00.001+05:30

The move underscores the difficulty of creating 'real' HTML apps and may hinder businesses' mobile ambitions

In December 2010, when Google unveiled its grand Chrome OS plan for Chromebook laptops that did everything on the Web -- no local apps or even storage -- a big question was how could that work in the real world where connectivity was often unavailable or the cost of a patchwork of connection plans quickly became too high to remain always connected. Google said it would deliver offline-capable Google Docs in March 2011, but it never did. It still hasn't. And Chrome OS is essentially a failed product today.

At the same time, Google Docs -- which is quite useful in that multiple people can work on different parts of a spreadsheet (such as a table) or calendar, and it serves essentially as a user-friendly content database -- worked horribly on mobile browsers like iOS's Safari and Android's Browser. Google came out with a mobile-optimized Google Docs website, but it still worked poorly.

All this is why Google revealed today that it has bought Quickoffice, a small company whose Quickoffice Pro productivity suite is the only serious business editing tool for Android and the only serious competitor to Apple's iWork on iOS -- it even beats iWork in several key functions. In other words, Google has thrown in the towel on making a real, rich app work via HTML only, at least in the mobile context. (Dataviz's once-leading Documents to Go has all but disappeared with no significant updates since BlackBerry maker Research in Motion bought its key assets 18 months ago.)

If any company could have -- and should have -- made mobile Web apps work like native local apps, it is Google. For Google to have given up means that the chances for Microsoft to make its Office 365 suite work on mobile are remote at best; Office 365 too is essentially unusable on mobile devices.

UPDATE: I should point out that Google called me after this post was published to strongly object to the characterization that it has given up on HTML for such apps, and a spokeswoman said in fact Google is very strongly committed. She cited the update to Chrome OS last week that adds Quickoffice-derived technology to the Google Docs viewer and says that offline editing is working in beta at Google. Perhaps, but I've heard similar commitments before and haven't yet seen it translate on the ground. Enough promises and beta -- it's time deliver it for real. If the Quickoffice acquisition can help make that happen, great! Other commentators have interpreted the Quickoffice acquisition as a way to compete better with Microsoft Office, perhaps with a Metro version for Windows 8 to make Google Docs seem less Webby and more appy. Perhaps, but Quickoffice has no history on any Microsoft or desktop platform.

What I see as the limits of HTML for "real" apps is not the only implication of Google's purchase of Quickoffice. The buyout could lead to a real dilemma for businesses that use iPhones and iPads, which have become the new corporate standards. Apple and Google are, to put it mildly, at war, and it's easy to imagine that Apple will find some way to punish Google by withholding approval for future versions of Quickoffice, especially the badly designed Quickoffice Connect app that tried to deliver a cross-platform version of iCloud. (UPDATE: Quickoffice has since announced that it will shut down Connect and move users' data to Google Drive as of July 15.) Likewise, it's easy to imagine that Google will pull Quickoffice from iOS or deliver an inferior version (as it does for most of its iOS apps) to spite Apple and steer users to Android.

In recent months, Quickoffice has partnered with several major mobile management vendors, incorporating their security APIs so that IT can manage the contents within Quickoffice, such as to prevent use in other apps or to wipe the data from users' devices if they leave the company. That's positioned Quickoffice to be the corporate mobile office-suite standard on the two mobile OSes that matter today (iOS and Android); given how poor Microsoft Office for Windows Phone 7 is, you could easily imagine Quickoffice delivering a version for that platform should it finally gain user adoption.

Like Apple and Microsoft, Google is trying to create a proprietary ecosystem, so it favors its Chrome browser, Google+ social network service, and Android mobile OS, and it is working with other ecosystems only to the extent it has to. If that strategy is applied to Quickoffice, any enterprise hopes of there being a standard mobile office tool that works across the major platforms and offers IT-friendly capabilities.

Effective Technical Communication By M.Ashraf Rizvi

2012-01-27T09:36:00.000+05:30

E-Commerce An Indian Perspective

2012-01-27T09:31:00.000+05:30

2012-01-27T09:12:00.000+05:30

C# Mock Test question and answers.

1. Which of the following statements are correct?

I. Reference types are either stack-allocated or allocated inline in a structure.
II. Value types are heap-allocated.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

2. I.    When a value type is boxed, an entirely new object must be allocated and constructed.
II.    The value type is stored on the garbage collected heap.
III.    Unboxing a value type packages it inside an instance of the Object reference type.

Only I and II are correct.

Only I and III are correct.

Only II and II are correct.

Only I II III are correct.

3. I. Assigning one value type variable to another copies the contained value.
II. It is possible to derive a new type from a value type.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

4. I. Variables of reference types referred to as objects and store references to the actual data.
II. String is a built-in value type.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

5. I. Nullable types represent value-type variables that can be assigned the value of null.
II. We can create a nullable type based on a reference type.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

6. I. It is possible for a value type to contain the null value.
II. Each value type has an implicit default constructor that initializes the default value of that type.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

7. I. Local variables in C# must be initialized before being used.

II. Using the new operator calls the default constructor of the specific type and assigns the default value to the variable.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

8. I. We can assign values of any type to variables of type object.

II. When a variable of a value type is converted to object, it is said to be unboxed.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

9. I. Boxing is an explicit conversion from an interface type to a value type that implements the interface.

II. An unboxing operation consists of checking the object instance to make sure it is a boxed value of the given value type.
III. An unboxing operation consists of copying the value from the instance into the value-type variable.

Only I and II are correct.

Only I and III are correct.

Only II and III are correct.

Only I II III are correct.

10. I. Variables of the value types store references to the actual data while those of the reference types store data.

II. It is possible to convert a value type to a reference type and back again to value types.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

11. All value types are derived implicitly from which of the following class?

System.DataType.ValueType

System.ValueType

System.DataValueType

System.ValueType.DataType

12. Which of the following is NOT an Integer?

Char

Byte

Short

Integer

13. Which of the following statements are correct?

I. A jump statement such as a break is required after each case block excluding the last block if it is a default statement.
II. C# always supports an implicit fall through from one case label to another.
Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

14. I. In nested if statements the else clause belongs to the last if that does not have a corresponding else.
II. It is not possible to extend the if statement to handle multiple conditions using the else-if arrangement.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

15. I. The if statement selects a statement for execution based on the value of a Boolean expression.
II. After executing the if statement, control is transferred to the next statement.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

16. I. The switch statement is a control statement that handles multiple selections and enumerations by passing control to one of the case statements within its body.
II. The switch statement can include any number of case instances with two case statements having the same value.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

17. Which of the following statements are correct?

I. Branching is performed using jump statements which cause an immediate transfer of the program control.
II. The goto statement passes control to the next iteration of the enclosing iteration statement in which it appears.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

18. Which of the following statements are correct?

I. Because the test of conditional expression takes place before the execution of the loop, therefore, a for statement executes zero or more times.
II. All of the expressions of the for statement are not optional.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

19. Which of the following can be used to terminate a while loop and transfer control outside the loop?

I.    break statement
II.    goto statement
III.    return statement
IV.    throw statement

Only I

Only I and II

Only III

I II III and IV

20. I. If we wish to execute more than one statement, multiple statements can be conditionally executed by including them into blocks using { }.
II. The statements to be executed upon testing the condition can be of any kind, including another if statement nested into the original if statement.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

21. I. The body loop of the do statement is executed at least once regardless of the value of the expression.
II. The for loop is handy for iterating over arrays and for sequential processing.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

22. Which of the following statements are correct? I. Attempting to unbox null or a reference to an incompatible value type will result in an InvalidCastException. II. There is no conversion between the bool type and other types. III. Constants of the char type can be written as character literals, hexadecimal escape sequence or Unicode representation.

Only I and II are correct.

Only I and III are correct.

Only II and III are correct.

Only I II III are correct.

23. Which of the following statement is correct about the code snippet given below? using System ; namespace ConsoleApplication1 { class Program { static void Main ( string[ ] args ) { byte mybyte = 256 ; Console.WriteLine ( mybyte ) ; } } }

The code reports an error.

The code causes System.InvalidCastException

The code causes System.OutOfRangeException.

The code gives an output as 256.

24. Which of the following statement is correct about the code snippet given below? using System ; namespace ConsoleApplication1 { class Program { static void Main ( string[ ] args ) { decimal d = 9.1m ; int y = 3 ; Console.WriteLine ( d + y ) ; } } }

The code reports an error.

The code causes System.TypeMismatchException.

The code causes System.InvalidCastException.

The code gives an output as 12.1.

25. Which of the following statement is correct about the code snippet given below? using System ; namespace ConsoleApplication1 { class Program { static void Main ( string[ ] args ) { decimal x = 0.999m ; decimal y = 99999m ; Console.WriteLine ( ( Convert.ToString ( x ) ) + " " + ( Convert.ToString ( y ) ) ) ; } } }

The code reports an error as type decimal cannot be converted to type string.

The code causes System.InvalidCastException.

The code gives an output as 1 99999.

The code gives an output as 0.999 99999.

26. Which of the following statement is correct about the code snippet given below? using System ; namespace ConsoleApplication1 { class Program { static void Main ( string[ ] args ) { char c = ‘0' ; bool b = c ; Console.WriteLine ( b ) ; } } }

The code reports an error.

The code causes System.InvalidCastException.

The code gives output as False.

The code gives output as true

27. Which of the following statement you will add to the code snippet given below to store the summation of x and y in z? using System ; namespace ConsoleApplication1 { class Program { static void Main ( string[ ] args ) { byte x = 10, y = 20, z ; // Add statement here } } }

z = x + y ;

z = ( byte ( x + y ) ) ;

z = ( byte ) ( x + y ) ;

( byte ) z = x + y ;

28. using System ;
namespace ConsoleApplication1
{
class Program
{
static void Main ( string[ ] args )
{
bool? letter = Convert.ToBoolean ( 5 ) ;
Console.WriteLine ( letter ) ;
}
}
}

The code reports an error as type int cannot be stored as nullable type.

The code causes System.InvalidOperationException.

The code causes System.InvalidCastException.

The code gives an output as True.

31. using System ;
namespace ConsoleApplication1
{
class Program
{
static void Main ( string[ ] args )
{
int i = 123 ;
object o = i ;
short j = ( short ) o ;
Console.WriteLine ( j ) ;
}
}
}

The code reports an error.

The code causes System.InvalidCastException.

The code gets compiled successfully but does not give any output.

The code gives an output as 123.

29. I. When a variable of type object is converted to a value type, it is said to be boxed.

II. Boolean variable cannot have a value of null.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

30. I. A common use of continue is to transfer control to a specific switch-case label or the default label in a switch statement.
II. The do statement executes a statement or a block of statements enclosed in {} repeatedly until a specified expression evaluates to false.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

31. Which of the following statements are correct?

I. We can cast the integral character codes.

II. A char can be implicitly converted to only int data type.

III. There are no implicit conversions from other types to the char type.

Only I and II are correct.

Only I and III are correct.

Only II and III are correct.

Only I II III are correct.

32. Which of the following statements are correct?

I. If the interger exceeds the range of byte, a compilation error will occur.

II.Byte cannot be implicitly converted to float.

III.We cannot implicitly convert non-literal types of larger storage to byte.

Only I and II are correct.

Only I and III are correct.

Only II and III are correct.

Only I II III are correct.

33. using System ;

namespace ConsoleApplication1
{
class Program
{
static void Main ( string[ ] args )
{
int i = 123 ;
object o = i ;

I=456;

System.Console.WriteLine(Conveert.ToString(i)+””Convert.ToString(o));

}
}
}

123 123

456 456

123 456

456 123

34. Which of the following statements are correct?

I . The foreach statement repeats a group of embedded statement for each element in an array or an object collection.

II. The foreach statement is used to iterate through the collection to get the desired information and should be used to change the content of the collection to avoid unpredictable side effect.

Only I is correct.

Only II is correct.

Both I and II are correct.

Both I and II are incorrect.

35. Which of the following statement is correct about the code snippet given below?

using System ;

namespace ConsoleApplication1

{

class Program

{

static void Main ( string[ ] args )

{

bool? flag = null ;

Console.WriteLine ( Convert.ToBoolean ( flag ) ) ;

}

The code reports an error as value null cannot be converted to type string.

The code causes System.InvalidOperationException.

The code gets compiled successfully but does not give any output.

The code gives an output as False.

36. Which of the following statement is correct about the code snippet given below?

using System ;

namespace ConsoleApplication1

{

class Program

{

static void Main ( string[ ] args )

{

Bool?letter = convert.ToBoolean(5);

Consol.WriteLine(Letter);

Ans: The code gives an output as True.

Oracle SQL Quick Reference By Oracle

2012-01-07T13:44:00.000+05:30

Oracle SQL Quick Reference By Oracle

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Oracle SQL Plus Reference Guide By Oracle

2012-01-07T13:41:00.001+05:30

Oracle SQL Plus Reference Guide By Oracle

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Business Management Using Information Technology

2011-11-06T16:28:00.000+05:30

Using information technology to gain and manage knowledge

Information technology offers powerful tools to help you gain and make the best use of knowledge. Some of the systems can be complex to set up and time-consuming to maintain. You need to choose systems that fit with your business and that will improve it without becoming a burden. You may find it useful to consult an IT specialist.
The main types of information technology used in knowledge management are described below.

Database tools

Databases organise information so it can be easily accessed, managed and updated. For instance, you might have a database of customers containing their contact information, their orders and preferences. For more information, see our guide on the benefits of databases.
A data warehouse is a central storage area you might use if you have a variety of business systems, or a range of information in different digital formats. Many businesses now use digital asset management to store, manage and retrieve information, and this can be particularly helpful if you sell online. It is, however, a complex area technically and in task management, so you may wish to seek specialist advice from an IT consultant. See our guide to ensure that you comply with data protection legislation.
Data mining is a process in which all the data you collect is sorted to determine patterns. For instance, it can tell you which products are most popular and whether one type of customer is likely to buy a particular item. Read an introduction to data mining on the About website - Opens in a new window.
Reporting and querying tools let you create reports interpreting data in a particular way. How many of your sales have been handled by one particular employee, for instance?

Web-based tools

Business intelligence portals are websites that bring together all sorts of potentially useful information, such as legal issues or details of new research.
The internet and search engines can be a powerful source of knowledge, although be certain to check the credibility of your information source. Internet newsgroups can be specific sources of business information, but check the authors' other postings before deciding how to view their opinions and claimed facts.
An intranet is a secure internal network for the sole use of your business. Read about the benefits of intranets on the Intranet Journal website - Opens in a new window.
An extranet is similar to an intranet but can be extended to customers and suppliers. Read about the benefits of extranets on the National Computing Centre website - Opens in a new window.
Social software, such as wikis, blogs and social networking sites, can also be useful when it comes to sharing knowledge.
A wiki is a website that allows different users to publish and edit the same pages quickly, making it possible for teams to record their collective knowledge. A blog allows one individual to share knowledge with other people in a business and social networking sites are an easy way to communicate informally.
You can read more about these tools in our guide web 2.0: a guide for business.

Customer analysis tools

Customer relationship management software helps you build up a profile of your customer database and enables you to target them through email, telephone or postal marketing campaigns. See our guide on customer relationship management.
Call-centre systems enable you to serve large numbers of customers if you sell by telephone.
Website log-file analysis helps you to analyse how customers use your website so you can improve its effectiveness.
Systems to analyse and file customer letters, suggestions, emails, and call-centre responses, which will enable you to spot trends, improve customer service and develop new products, services and systems.

12 Tips to Maintain a Virus Free Computer

2011-09-04T23:16:00.002+05:30

Is your computer infected with virus? Do you often get mysterious error messages? Well this is a common problem faced by almost all the computer users across the globe. There are many viruses and worms out there that could infect your computer. Some are harmless, but, they do have the capacity to do any number of nasty things, up to and including, erasing all data from your computer. However there are ways to keep viruses away from your PC. Here are the 12 tips to maintain a virus free computer.

1. Email is one of the common ways by which your computer can catch a virus. So it is always recommended to stay away from SPAM. Open only those emails that has it’s origin from a trusted source such as those which comes from your contact list. If you are using your own private email host (other than gmail, yahoo, hotmail etc.) then it is highly recommended that you use a good anti-spam software. And finally NEVER click on any links in the emails that comes from untrusted sources.

2. USB thumb/pen drives is another common way by which viruses spread rapidly. So it is always a good habit to perform a virus scan before copying any data onto your computer. NEVER double-click the pen drive to open it. Instead right-click on it and select the option “open”. This is a safe way to open a pen drive.

3. Be careful about using MS Outlook. Outlook is more susceptible to worms than other e-mail programs, unless you have efficient Anti-Virus programs running. Use Pegasus or Thunderbird (by Mozilla), or a web-based program such as Hotmail or Yahoo (In Firefox).

4. As we all know, Internet is the main source of all the malicious programs including viruses, worms, trojans etc. In fact Internet contributes to virus infection by up to 80%. So here are the tips for safe surfing habits so that you can ward off virus infection up to the maximum extent.

• Don’t click on pop-up windows that announce a sudden disaster in your city or announce that you’ve won an hourly prize. They are the ways to mislead Internet users and you should never trust them.

• You can also use a pop-up blocker to automatically block those pop-ups.

5. Most of us use search engines like Google to find what we are looking for. It is quite obvious for a malicious website to get listed in the search results. So to avoid visiting those untrusted malicious websites, you can download and install the AVG LinkScanner which is a freeware. This tool can become very handy and will help you to stay away from malicious websites.

6. Install a good antivirus software and keep it updated. Also perform full system scan periodically. It is highly recommended that you turn on the automatic update feature. This is the most essential task to protect your PC from virues. If PC security is your first option then it is recommended that you go for a shareware antivirus software over the free ones. Most of the antivirus supports the Auto-Protect feature that provides realtime security for your PC. Make sure that this feature is turned on.

7. Install a good Antispyware program, that operates against Internet malware and spyware.

8. Never open any email attachments that come from untrusted sources. If it is a picture, text or sound file (these attachments end in the extensions .txt, .jpeg, .gif, .bmp, .tif, .mp3, .htm, .html, and .avi), you are probably safe, but still do a scan before opening.

9. Do not use disks that other people gave you, even from work. The disk could be infected with a virus. Of course, you can run a virus scan on it first to check it out.

10. Set up your Windows Update to automatically download patches and upgrades. This will allow your computer to automatically download any updates to both the operating system and Internet Explorer. These updates fix security holes in both pieces of software.

11. While you download files from untrusted websites/sources such as torrents, warez etc. make sure that you run a virus scan before executing them.

12. And finally it is recommended not to visit the websites that feature illegal/unwanted stuffs such as cracks, serials, warez etc. since they contribute much in spreading of viruses and other malicious programs.

How to Detect Trojan Horse ?

2011-09-04T23:13:00.001+05:30

Detecting a Trojan
Awareness and preventive measures are the best defense against Trojans. Educate users not to install applications downloaded from the Internet and email attachments. Most commercial anti-virus products can automatically scan and detect backdoor programs before they can cause damage.

Using Anti-Trojan Software:
Antivirus software is designed to detect and delete Trojan horses, as well as preventing them from ever being installed. Although it is possible to remove a Trojan horse manually, it requires a full understanding of how that particular Trojan horse operates. In addition, if a Trojan horse has possibly been used by a hacker to access a computer system, it will be difficult to know what damage has been done and what other problems have been introduced.

Manual Detection
Though manual removal/detection of Trojans is difficult, but this is best way to remove the Trojans completely from the computer. With practice, it becomes easy to manually detect/remove the Trojans

TCPView
TCPView is a Windows program that will show you detailed listings of all TCP and UDP endpoints on your system, including the local and remote addresses and state of TCP connections. On Windows NT, 2000, and XP, TCPView also reports the name of the process that owns the endpoint. TCPView provides a more informative and conveniently presented subset of the Netstat program that ship with Windows. The TCPView download includes Tcpvcon, a command-line version with the same functionality.
Tcpvcon is the command-line version of TCPView. Its usage is similar to that of the built-in Windows netstat utility. Just typing tcpvcon in a CMD box runs the Application.

Process Viewer
Process Viewer (PrcView) (www.teamcti.com/pview/prcview.htm) is a free GUI-based process viewer utility that displays detailed information about processes running under Windows. For each process it displays memory, threads, and module usage. For each DLL, it shows full path and version information. PrcView comes with a command-line version that allows you to write scripts to check whether a process is running and stop it, if necessary.

Process Explorer

Process Explorer is a freeware computer program for Microsoft Windows created by Sysinternals, which was acquired by Microsoft Corporation. Process Explorer is a system monitoring and examination utility. It provides the functionality of Windows Task Manager along with a rich set of features for collecting information about processes running on the user’s system. It can be used as the first step in debugging software or system problems. Process Explorer can be used to track down problems. For example, it provides a means to list or search for named resources that are held by a process or all processes. This can be used to track down what is holding a file open and preventing its use by another program. Or as another example, it can show the command lines used to start a program, allowing otherwise identical processes to be distinguished. Or like Task Manager, it can show a process that is maxing out the CPU, but unlike Task Manager it can

Show which thread (with the call stack) is using the CPU – information that is not even available under a debugger.

BackTrack 5 – The Most Advanced Linux Security Distribution & LiveCD

2011-09-04T23:04:00.001+05:30

We have of course been following BackTrack since the very early days, way back in 2006 when it was just known as BackTrack – A merger between WHAX and Auditor. They’ve come a long way and BackTrack is now a very polished and well rounded security distro, most of the others have dropped off the map leaving BackTrack as the giant in the security LiveCD space.

The last major release was BackTrack Final 4 Released – Linux Security Distribution – back in January 2010.
The BackTrack Dev team has worked furiously in the past months on BackTrack 5, code name “revolution” – they released it on 2011,May 10th. This new revision has been built from scratch, and boasts several major improvements over all our previous releases. It’s based on Ubuntu Lucid LTS – Kernel 2.6.38, patched with all relevant wireless injection patches. Fully open source and GPL compliant.

The interesting part for me is that the new .ISO downloads offer multiple versions, including a choice between GNOME and KDE desktops and the images include ARM, 32-Bit and 64-Bit versions.

New in Version 5 :

Based on Ubuntu 10.04 LTS
Linux kernel 2.6.38 (with wireless injection patches)
KDE 4.6
GNOME 2.6
32-bit and 64-bit support
· Metasploit 3.7.0
Forensics mode (a forensically sound instance)
Stealth mode (without generating network traffic)
Initial ARM image of BackTrack (for Android-powered devices)

How to Create your own Run Command ?

2011-09-04T23:00:00.000+05:30

I talk a lot about Windows, and using the “Run” command is a large part of it. It is a simple and easy method of accessing programs quickly. If you happen to want to make a shortcut to an application your own way, guess what, you can!
Let’s do it:
Step 1: Go to “Start,” “Run,” (told you we use it a lot) and type regedit.

Step 2: Navigate to the following:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Apps Path
Step 3: Create a new folder/key under Apps Path. (Right-Click Apps Path and click “New,” “Key.”)
Step 4: Title the new folder/key the name of the application, e.g. firefox.exe.
Step 5: Right-Click the default string value (the thing automatically created in your new folder) and click Modify.
Step 6: Change the value to the path of the executable you are attempting to run. E.g. C:\Program Files\Mozilla Firefox\firefox.exe.
Step 7: Create a new “String Value” by right-clicking under the default value (the thing we just edited) and select “New,” “String Value.” Name it Path and enter the value as the same path you previously entered.

Step 8: Done! Now, all you need to do is go to “Start,” “Run,” and type the name of your command!

Forgotten Ubuntu Password – Reset within minutes

2011-09-04T22:53:00.000+05:30

If you’ve ever forgotten your password, you aren’t alone… it’s probably one of the most common tech support problems I’ve encountered over the years. Luckily if you are using Ubuntu they made it incredibly easy to reset your password.

All it takes is adjusting the boot parameters slightly and typing a command or two, but we’ll walk you through it.

Reset Your Ubuntu Password

Reboot your computer, and then as soon as you see the GRUB Loading screen, make sure to hit the ESC key so that you can get to the menu.

Root Shell – Easy Method

If you have the option, you can choose the “recovery mode” item on the menu, usually found right below your default kernel option.

Then choose “Drop to root shell prompt” from this menu.

This should give you a root shell prompt.

Alternate Root Shell Method

If you don’t have the recovery mode option, this is the alternate way to manually edit the grub options to allow for a root shell.

First you’ll want to make sure to choose the regular boot kernel that you use (typically just the default one), and then use the “e” key to choose to edit that boot option.

Now just hit the down arrow key over to the “kernel” option, and then use the “e” key to switch to edit mode for the kernel option.

You’ll first be presented with a screen where you can find this written “ro single”

You’ll want to remove the “ro single” part with the backspace key, and then add this onto the end:

rw init=/bin/bash

Once you hit enter after adjusting the kernel line, you’ll need to use the B key to choose to boot with that option.

At this point the system should boot up very quickly to a command prompt.

Changing the Actual Password

You can use the following command to reset your password:

passwd <username>

After changing your password, use the following commands to reboot your system. (The sync command makes sure to write out data to the disk before rebooting)

sync
reboot –f

I found that the –f parameter was necessary to get the reboot command to work for some reason. You could always hardware reset instead, but make sure to use the sync command first.
And now you should be able to login without any issues.

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Free Download X2Blue (Bluetooth Hacking Software)

2011-08-22T16:16:00.000+05:30

X2Blue (www.computereducation.co.cc).jar

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Free Download Network Password Recovery Software

2011-08-22T16:12:00.000+05:30

When you connect to a network share on your LAN or to your .NET Passport account, Windows XP allows you to save your password in order to use it in each time that you connect the remote server. This utility recovers all network passwords stored on your system for the current logged-on user.

Which passwords this utility can recover ?

Login passwords of remote computers on your LAN.
Passwords of mail accounts on exchange server (stored by Outlook 2003)
Password of MSN Messenger account (Only until version 7.0, When you connect to a network share on your LAN or to your .NET Passport account, Windows XP allows you to save your password in order to use it in each time that you connect the remote server. This utility recovers all network passwords stored on your system for the current logged-on user.

Which passwords this utility can recover ?
Login passwords of remote computers on your LAN.
Passwords of mail accounts on exchange server (stored by Outlook 2003)
Password of MSN Messenger account (Only until version 7.0 )

System Requirements

This utility works properly on Windows XP only when you logged on as user with Administrator privileges. You can also use this utility for recovering network passwords under Windows 98/ME. Windows 2000 is not supported, because this version of operating system doesn't save the network passwords.

System Requirements

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Find Windows XP Product Key From Your Installation CD [How To]

2011-08-15T16:20:00.001+05:30

Have you lost your Windows CD Key and are desperately looking for it? No backups, nothing. What do you do now? Well till you have your Original installation you can easily find the Product key without breaking a sweat.

Here are the simple steps you need to perform in order to get your Product Key from the installation CD.
(Note: This may only work for certain OEM CDs, if it does not work for you, you can check out our earlier post on how you can find your Windows XP Product key.)

Insert the Installation CD into your CD / Drive Drive.
Explore the CD and navigate to the i386 folder.
Open the file UNATTEND.txt and scroll down to the last line.
You will find your Windows XP Product key there.

We were able to find the CD key on a Windows XP Corporate Edition installation CD and would love to know if you were able to find it on your own installation CDs. Do let us know through your comments on how it went for you.

Tools to Find and Change Your Windows and Microsoft Office Product Keys

2011-08-15T16:15:00.001+05:30

There are many a times when you may have misplaced your product keys for Softwares such as Windows XP, Windows Vista, Microsoft Office and so on, or may have bought a assembled PC where the vendor may have not given you your product key.

Instead of cursing any one of them you can make use of some real nice tools to find or change your Microsoft Windows and Microsoft Office Product Keys, these softwares can easily help you find the product keys for any Microsoft softwares you may have installed on your system.

Why Should you need this software?

Well that’s a question many of you may ask but once you have lost a product key, you have effectively lost your license for the software. The software in itself will not be able to show you the product key you have used to register the software, so having a handy utility to retrieve those lost product keys are a must.

Also at times you may want to change the product key to use a new license you have just acquired, nevertheless these utilities allow you to both view and change your windows and office product keys.

Let us have a look at the numerous product key retrievers that are available to be used free of cost.

Windows and Office Product Key Finders

Magical Jelly Bean Keyfinder

This is one of the most popular softwares you can use to find and retrieve your Microsoft office or Windows product keys. It also allows you to easily change the product keys. The software works on Windows 95, 98, ME, NT4, 2000, XP, Server 2003, Windows Vista, Office 97, Office XP, and Office 2003.

More Info | Download

ProduKey

ProduKey is a software similar to Magical Jelly Bean and allows you to find keys for both Microsoft Windows and Microsoft Office.

More Info | Download

KeyFinder

KeyFinder can be used to retrieve your lost Windows XP Product Key. The page has a nice list differentiating between Product keys and OEM keys.

More Info | Download

CD Key Seizer

The software allows you to retrieve product keys for Windows 2000 and XP and Microsoft Office 2003 and 2007 along with Frontpage 2003.

More Info | Download

Other Softwares which will allow you to retrieve and change your CD keys

Summarizing

If you are stuck at finding the product keys are dread to reinstall or buy the license again these softwares may come in quite useful to you. You may also at some time want to renew your licenses and these ease to use softwares can easily help you update your CD keys for both Microsoft Windows and Microsoft Office softwares.

So stop paying money to those tech support guys and make use of these free softwares to save yourself the headache.

Top Free Screen Recorders to Record Your Screen Activities

2011-08-15T16:06:00.001+05:30

These days recording screen activities have become quite a popular way of blogging and doing presentations. The screen recorders act just like the print screen function but the difference is that it continuously records all your on screen activities just like a camcorder or digital camera.
These softwares can also be useful when you want to create screen casts for software usage instructions or a video to report a bug that occurred in a software.
There are many screen recording softwares available for you to record the screen activities, here are few of the best screen recorders that will allow you to create videos and presentation from your activities and which are free to use.

CamStudio Open Source

CamStudio is a open source software that allows you to record your screen activities and create AVI videos out of it, it also includes a built-in SWF producer that allows you to create bandwidth friendly flash videos.
In addition to that CamStudio allows you to add high-quality sound to the video and also create picture-in-picture videos by using your webcam videos.
This is one great software that you should definitely have to record your screen activities and create videos out of it.
Learn More | Download CamStudio Open Source | Download CamStudio Codec Pack

Free Screen Recorder

Free Screen Recorder is another screen recording software that can be used to capture screen activities into a AVI video file. Free screen recorder records every moment including mouse cursor movements, typing etc.
You can also record voice from the microphone which makes it easier to add your own commentary while the video is being recorded.
Learn More | Download

Freez Screen Recorder

Freez Screen Recorder allows you to record videos and also pause them. Like all the other softwares you can record any region of the screen or activities in a particular window in addition to recording all the activities of the full screen.
It also supports voice recording from the microphone, videotape or Internet.
Learn More | Download

AutoScreenRecorder

AutoScreenRecorder allows you to create AVI files by recording screen activities. You can record the mouse pointer, a rectangle area or choose to record activities taking place in a application window. You can also choose to record the full screen for activities.
You can also choose to buy a full fledged version of AutoScreenRecorder which adds in more features to the software like generating flash video files and recording voice and sound in the video.
Learn More / Download

Summarizing

If you are looking for softwares to create demo videos and presentations or even plan to start video blogging, these tools are quite handy. Not only are they completely free to use but also add more utility to your computer life.
If you think there are better options please do share it with other readers using the comments form. I am definitely looking to try out more alternatives.