Programing Tech

10 Useful PHP Code Snippets For Programmers

noreply@blogger.com (Anonymous) — Tue, 17 Mar 2015 00:29:00 +0000

I am going to share most useful PHP code snippets that a PHP developer will need at any point in his career. Few of the snippets are shared from my projects and few are taken from useful php websites from internet.

1. Detect HTTPS Server:

you can know if your server is HTTPS or not.

if ($_SERVER['HTTPS'] != "on") { 
 echo "This is not HTTPS";
}else{
 echo "This is HTTPS";
}

2. Get User IP Address:

The above code will work even in case your client is behind proxy server. Below function to get real IP address of client.

function getRealIPAddress()
{
    if (!empty($_SERVER['HTTP_CLIENT_IP']))   //check ip from share internet
    {
        $ip=$_SERVER['HTTP_CLIENT_IP'];
    }
    elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR']))   //to check ip is pass from proxy
    {
        $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
    }
    else
    {
        $ip=$_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}

3. Validate email Address:

E-mail validation is perhaps the most used validation in web forms, this code will validate email address.

 
function is_valid_email($email)
{
    if(preg_match("~([a-zA-Z0-9!#$%&'*+-/=?^_`{|}~])@([a-zA-Z0-9-]).([a-zA-Z0-9]{2,4})~",$email)) {
        return true
    else
        return false;
}

4. Detect if Ajax Request:

scope of this function is to check whether request is done via ajax or not.

 
public function isAjaxRequest(){
    if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) &&  strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest') {
        // an ajax call
        return true;
    }
    else{
        // non ajax call
        return false;
    }
}

5. HTTP Redirection in PHP:

Use this to Redirect user to other page.

 

 header('Location: http://www.site.com/index.php'); // add your url

6. Force file Download:

Provide files to the user by forcing them to download.

 

function force_download($file)
{
    if ((isset($file))&&(file_exists($file))) {
       header("Content-length: ".filesize($file));
       header('Content-Type: application/octet-stream');
       header('Content-Disposition: attachment; filename="' . $file . '"');
       readfile("$file");
    } else {
       echo "No file selected";
    }
}

7. Browser Detection script in PHP:

Test a string to see if it contains HTML within it.

 

 $useragent = $_SERVER ['HTTP_USER_AGENT'];
    echo "Your User Agent is: " . $useragent;

8. Check String For Html:

Test a string to see if it contains HTML within it.

 

function has_html($string){
    if(strlen($string) != strlen(strip_tags($string))){
        return true;
    }
    return false;
} 

var_dump(has_html("This string doesn't have any html"));
var_dump(has_html("This string has a
line break"));

9. Creating and Parsing JSON :

Following is the PHP code to create the JSON data format of above example using array of PHP.

 
$json_data = array ('id'=>1,'name'=>"rolf",'country'=>'russia',"office"=>array("google","oracle"));
   echo json_encode($json_data);

Following code will parse the JSON data into PHP arrays.

 
$json_string='{"id":1,"name":"Zahid","country":"Pakistan","office":["hotmail","oracle"]} ';
   $obj=json_decode($json_string);
   //print the parsed data
   echo $obj->name; //displays rolf
   echo $obj->office[0]; //displays hotmail

10. PHP Strong Password Generator :

This code an generate strong password of any length and any complexity (1 to 5).

 

function generate_password($length = 8, $complex=3) {
   $min = "abcdefghijklmnopqrstuvwxyz";
   $num = "0123456789";
   $maj = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
   $symb = "!@#$%^&*()_-=+;:,.?";
   $chars = $min;
   if ($complex >= 2) { $chars .= $num; }
   if ($complex >= 3) { $chars .= $maj; }
   if ($complex >= 4) { $chars .= $symb; }
   $password = substr( str_shuffle( $chars ), 0, $length );
   return $password;
}
echo generate_password(8);

Useful JavaScript and Jquery Code Snippets

noreply@blogger.com (Anonymous) — Thu, 10 Oct 2013 02:26:00 +0000

JavaScript and Jquery is used on thousands upon thousands of web pages. It’s one of the most common libraries to insert into pages, and it makes DOM manipulation a snap. Using Jquery you will be able to change an existing element within a number of ways as well as: decreasing page load time and thereby giving your end users a better experience when visiting your site.

I have put together a series of helpful Jquery code snippets you may save and copy to use at your own discretion.

1. Allow Numeric Input
Usage:

 <input type="text" id="txtCount" runat="server" onkeypress="ValidateNumber(this);"  />

JavaScript :

 
function ValidateNumber(evt) {  
  evt = (evt) ? evt : window.event  
  var charCode = (evt.which) ? evt.which : evt.keyCode  
  if (charCode > 31 && (charCode < 48 || charCode > 57)) {  
     return false  
  }  
   return true  
}

2. Currency Format
Usage:

   <input type="text" id="txtMinimumPurchase"  value="0.00" onblur="this.value=formatCurrencyNumber(this.value);" />

JavaScript :

function formatCurrencyNumber(num) {  
  num = num.toString().replace(/\$|\,/g, '');  
  if (isNaN(num))  
  num = "0";  
  sign = (num == (num = Math.abs(num)));  
  num = Math.floor(num * 100 + 0.50000000001);  
  cents = num % 100;  
  num = Math.floor(num / 100).toString();  
  if (cents < 10)  
  cents = "0" + cents;  
  for (var i = 0; i < Math.floor((num.length - (1 + i)) / 3); i++)  
    num = num.substring(0, num.length - (4 * i + 3)) + ',' +  
    num.substring(num.length - (4 * i + 3));  
    return (((sign) ? '' : '-') + num + '.' + cents);  
 }

3. Number of Days of a Month and Checking Leap Year

 
 function IsleapYear(year) {  
   var isLeapYear = year % 4; // == 0  
   if (isLeapYear == 0)  
       return true;  
   else  
       return false;  
   }  

   function GetNumberofDaysinMonth(month, year) {  
     var noOfDays;  
     switch (parseInt(month)) {  
     case 1:  
     noOfDays = 31;  
     break;  
     case 2:  
     noOfDays = parseInt(IsleapYear(year) == true ? 29 : 28);  
     break;  
     case 3:  
     noOfDays = 31;  
     break;  
     case 4:  
     noOfDays = 30;  
     break;  
     case 5:  
     noOfDays = 31;  
     break;  
     case 6:  
     noOfDays = 30;  
     break;  
     case 7:  
     noOfDays = 31;  
     break;  
     case 8:  
     noOfDays = 31;  
     break;  
     case 9:  
     noOfDays = 30;  
     break;  
     case 10:  
     noOfDays = 31;  
     break;  
     case 11:  
     noOfDays = 30;  
     break;  
     case 12:  
     noOfDays = 31;  
     break;  
     }  
     return noOfDays;  
}

4. Scroll Page to a Specific Element

 
1:  function ScrollToElement(el) {  
2:    try {  
3:      $('html, body').animate({ scrollTop: $(el).offset().top - 200 }, 'slow');  
4:    }  
5:    catch (err) {  
6:    }  
7:  }

Best HTML5 Frameworks for Mobile Application Development

noreply@blogger.com (Anonymous) — Sat, 30 Jun 2012 11:31:00 +0000

Mobile apps have never been this vital and popular before. With the easy and convenient availability of smart phones etc., the development of mobile phone apps have taken a new high. Users look for highly interactive mobile apps, which contribute towards making their lives interesting and convenient.

Creating web apps and sites for the Mobile Web has its own sets of challenges and techniques. From UIs optimized for fingers instead of mouse cursors to the bandwidth limitations that most portable personal devices have, developing for mobile devices requires a paradigm shift for those of us who’ve traditionally created products aimed at desktops.

Some common characteristics of JavaScript mobile web development frameworks:

Optimized for touch screen devices: Fingers as input devices instead of mouse cursors provide an extra set of challenges in user interface design. Mobile web development frameworks provide standard UI elements and event-handling specifically for mobile device platforms.

Cross-platform: Support for multiple mobile device platforms such iOS and Android allows you to get your app to a wide range of users.

Lightweight: Because of current bandwidth limitations, a stronger emphasis on lowering file weight is placed into mobile web development frameworks.

Uses HTML5 and CSS3 standards: Most mainstream mobile devices have web browsers that support HTML5 and CSS3, and so mobile web development frameworks take advantage of new features available in these upcoming W3C specifications for a better user experience. Below, you will find some of the most preferable mobile JavaScript frameworks that can improve your skills as a web developer.

Zepto.js

Zepto, as the title spoiled it for you, is a ~~mobile~~ JavaScript framework that rectifies both of the issues mentioned above. It has a very small code base and is feather weight at around 8kb. Zepto’s API is jQuery compatible. If you use jQuery, you already know how to use Zepto.

Sencha Touch

Sencha Touch is amongst the pioneers in the field of HTML5 frameworks used for developing applications for mobile phones. The power and usability of Sencha Touch lies in the fact that it allows the users to create the applications which function amazingly on the screen of Android and iPhone devices. In fact it is amongst the most preferred choice for creating applications aimed at devices supporting iOS, Android and BlackBerry. Sencha Touch particularly support HTML5, CSS3 and JavaScript. Thus it provides the users with the best of these three words – The multimedia (video and audio component) of HTML5, element backing up local storage, styling effects provided by CSS3 and other amazing features. If you require the application to be visually interactive, Sencha Touch is the best possible option. Besides, Sencha Touch is thoroughly documented and you also win yourself the support of its online community.

Phonegap

PhoneGap is an HTML5 app platform that allows you to author native applications with web technologies and get access to APIs and app stores. PhoneGap leverages web technologies developers already know best... HTML and JavaScript.

PhoneGap will use standards-based web technologies to bridge web applications and mobile devices. Plus, because PhoneGap apps are standards compliant, they’re future-proofed to work with browsers as they evolve.

jQuery Mobile

jQuery mobile framework takes the "write less, do more" mantra to the next level: Instead of writing unique apps for each mobile device or OS, the jQuery mobile framework allows you to design a single highly-branded web site or application that will work on all popular smartphone, tablet, and desktop platforms A unified, HTML5-based user interface system for all popular mobile device platforms, built on the rock-solid jQuery and jQuery UI foundation. Its lightweight code is built with progressive enhancement, and has a flexible, easily themeable design.

Titanium

Appcelerator is the first mobile platform to combine the flexibility of open source development technologies with the power of cloud services. Although we are talking about HTML5 framworks for developing mobile applications, here is one JavaScript based framework which deserves due attention. The interface of Titanium is based on JavaScript and its framework contains the native code modules. It can be used to render the web skills into native apps. The apps acts as if they have been coded in Objective C, which is vital of iPads and iPhones, or Java, which is required for developing Android apps. Titanium plays an important role in building apps which are social, easy to use, interactive and scalable.

Asp interview questions

noreply@blogger.com (Anonymous) — Mon, 01 Aug 2011 09:16:00 +0000

Q 1: What is the difference between web.config and machine.config ?

Answer: The settings made in the web.config file are applied to that particular web application only whereas the settings of machine.config file are applied to the whole asp.net applications configured on that server.

Q 2: What are the different types of sessions in ASP.Net? Name them.

Answer: Session Management can be achieved in two ways:
1)InProc
2)OutProc (again two types State Server and SQL Server)

InProc
Advantage:
1) Faster as session resides in the same process as the application
2) No need to serialize the data

Disadvantage:
1) Will degrade the performance of the application if large chunk of data is stored
2) On restart of IIS all the Session info will be lost

State Server
Advantage:
1) Faster than SQL Server session management
2) Safer than InProc. As IIS restart
won't effect the session data

Disadvantage:
1) Data need to be serialized
2) On restart of ASP.NET State Service session info will be lost
3)Slower as compared to InProc

SQL Server
Advantage:
1) Reliable and Durable
2) IIS and ASP.NET State Service
restart won't effect the session data
3) Good place for storing large chunk of data

Disadvantage:
1) Data need to be serialized
2) Slower as compare to InProc and State Server
3)Need to purchase Licensed
version of SQL Server

Q 3: What is the difference between autopostback and ispostback?

Answer:

Autopostback - Property of the control
IsPostback - Property of the Page class

Autopostback - get and set property to control postback on changes made for control.
for e.g.
this.ListBox1.AutoPostBack = true;
whenever user will select item, the page will get post back.

IsPostback - get property of the Page class, to check if page is post back i.e. if it is true then page has already executed Init function of the page else it is first time the page has requested to be executed.

Q 4: State the difference between a Session and an Application

Answer: Basically, in session state It allows you to store any type of data in memory on the server. The information is protected, because it is never transmitted to the client, and uniquely bound to a specific session. Every client that accesses the application has a different session and a distinct collection of information. Instance of every user is different which is differentiated by a session ID.

While in case of an application state, it allows you to store global objects that can be accessed by any client. That is the instance for every user is same.

Q 5: what is boxing and unboxing?

Answer:

Boxing is what happens when a value-type object is assigned to a reference-type variable.
Unboxing is what happens when a reference-type variable is assigned to a value-type variable.

Q 6: what is Reflection?

Answer: Reflection is a collection of classes which allow you to query assembly (classes/objects) metadata at runtime. Using reflection you can also create new types and their instances at runtime and invoke methods on these new type instances.

There are other uses for reflection. Compilers for languages such as JScript use reflection to construct symbol tables.

In .Net the classes in the System.Runtime.Serialization namespace use reflection to access data and to determine which fields to persist. You can use System.Reflection.Emit namespace to dynamically generate types.

1. C# (OOP Concepts part 1)

noreply@blogger.com (Anonymous) — Tue, 28 Jun 2011 20:49:00 +0000

Introducing Classes and Objects

A class defines constituent members which enable these class instances to have state and behavior.

e.g Vehicle class defined as:

public class Vehicle

{

public string Name;

public string vehicleNo;

public void ShowVehicleInformation()

{

Console.Write(this.Name);

Console.Write(this.vehicleNo);

}

Here Vehicle is some thing which has some chracteristics and behaviors.

An object is a building block of an OOP application. This building block encapsulates part of the

application, which may be a process, a chunk of data, or a more abstract entity. Objects in C# are created from types, just like the variables you have seen already. The type of an object is known by a special name in OOP, its class

e.g a variable is declared as

int myNumber = 10;

Similarly an object is declared as

Vehicle car = new Vehicle();

Here car is an object of Vehicle class. Vehicle can also be called a user defined data type.

Properties and Fields

Properties and fields provide access to the data contained in an object. This object data is what differentiates separate objects, because it is possible for different objects of the same class to have different values stored in properties and fields.

Both fields and properties are typed, so you can store information in them as string values, as int values, and so on.

e.g car object of Vehicle class has properties:

public string Name;

public string vehicleNo;

Methods

Methods are used to provide access to the object’s functionality.

e.g

public void ShowVehicleInformation()

{

Console.Write(this.Name);

Console.Write(this.vehicleNo);

}

Access Modifiers

All types and type members have an accessibility level, which controls whether they can be used from other code in your assembly or other assemblies. You can use the following access modifiers to specify the accessibility of a type or member when you declare it:

public

The type or member can be accessed by any other code in the same assembly or another assembly that references it.

private

The type or member can be accessed only by code in the same class or struct.

protected

The type or member can be accessed only by code in the same class or struct, or in a class that is derived from that class.

internal

The type or member can be accessed by any code in the same assembly, but not from another assembly.

Default access

A default access level is used if no access modifier is specified in a member declaration. The following list defines the default access modifier for certain C# types:

enum: The default and only access modifier supported is public.

class: The default access for a class is private. It may be explicitly defined using any of the access modifiers.

interface: The default and only access modifier supported is public.

struct: The default access is private with public and internal supported as well.

The default access may suffice for a given situation, but you should specify the access modifier you want to use to ensure proper application behavior.

Note: Interface and enumeration members are always public and no access modifiers are allowed.

Validation Controls (Asp.net Series # 1)

noreply@blogger.com (Anonymous) — Tue, 28 Jun 2011 18:19:00 +0000

Type of Validation Control:

RequiredFieldValidator : Ensures that the user does not skip an entry. e.g Mandatory Fields
CompareValidator: Compares a user's entry against a constant value, against the value of another control (using a comparison operator such as less than, equal, or greater than), or for a specific data type.
RangeValidator: Checks that a user's entry is between specified lower and upper boundaries. You can check ranges within pairs of numbers, alphabetic characters, and dates.
RegularExpressionValidator: Checks that the entry matches a pattern defined by a regular expression. This type of validation enables you to check for predictable sequences of characters, such as those in e-mail addresses, telephone numbers, postal codes, and so on.
CustomValidator: Checks the user's entry using validation logic that you write yourself. This type of validation enables you to check for values derived at run time.

Working Example of Validation Control:

Download Full Example Here

IPhone Development Basics (Part 2)

noreply@blogger.com (Anonymous) — Sun, 15 May 2011 19:40:00 +0000

Exploring the Objective-C File Structure

Header/Interface Files

Creating a class creates two different files: an interface (or header) file (.h) and an implementation file (.m). The interface file is used to define a list of all of the methods and properties that your class will be using.The implementation file, on the other hand, is where you’ll go to write the code that makes everything defined in the header file work.

The #import Directive: Directives are commands that are added to your files that help Xcode and its associated tools build your application.

The @interface Directive and Instance Variables: Line 3 uses the @interface directive to begin a set of lines (enclosed in {} braces) to describe all the instance variables that your class will be providing.

What’s a Protocol: Protocols are a unique feature of Objective-C that sound complicated but really aren’t. Sometimes you will come across features that require you to write methods to support their use—such as providing a list of items to be displayed in a table. The methods that you need to write are grouped together under a common name—this is known as a “protocol.”

Defining Methods: Lines 8 and 10 declare two methods that need to be implemented in the class:

The @property Directive: The @property directive is used in conjunction with another command called syn- thesize in the implementation file to simplify how you interact with the instance variables that you’ve defined in your interface.

Ending the Interface File: To end the interface file, add @end on its own line. This can be seen on line 14 of our example file:
Implementation Files

After you’ve defined your instance variables (or properties!) and methods in your interface file, you need to do the work of writing code to implement the logic of your application. The implementation file (.m) holds all of the “stuff” that makes your class work.

The #import Directive: The #import directive kicks things off in line 1 by importing the interface file associated with the class:

The @implementation Directive: The implementation directive, shown in line 3, tells Xcode what class the file is going to be implementing.

The @synthesize Directive: In line 5, we use the @synthesize directive to, behind the scenes, generate the code for the getters and setters of an instance variable:

Method Implementation: The implementation file must restate the method definitions, but, rather than ending them with a semicolon (;), a set of curly braces, {}, is added at the end, as shown in lines 7–9 and 11–13. All the magic of your programming will take place between these braces:

IPhone Development Basics (Part 1)

noreply@blogger.com (Anonymous) — Sun, 10 Apr 2011 14:04:00 +0000

Object Oriented Programming Overview

OOP Vocabulary:

Class: defines the grouping of data and code, the “type” of an object
Instance: a specific allocation of a class
Method: a “function” that an object knows how to perform
Instance Variable: a specific piece of data belonging to an object

Encapsulation: keep implementation private and separate from interface
Polymorphism: different objects, same interface
Inheritance: hierarchical organization, share code, customize or extend behaviors

Cocoa Framework

Objective-C:

Objective-C was created in the 1980s and is an extension of the C language. It adds many additional features to C and, most important, an OOP structure. Objective-C is primarily used for developing Mac and iOS applications and has attracted a devoted group of fol- lowers who appreciate its capabilities and syntax.

Objective-C Programming Basics
This section describes the basic Objective-C Syntax:

Declaring variables.
Allocating and initializing objects.
Using an object’s instance methods.
Making decisions with expressions.
Branching and looping

Declaring Variables: Instance variables store information that is available across all the methods in your class. Most commonly, you’ll be declaring several variables at the start of your methods, using them for various calculations, and then getting rid of them when you’ve finished with them.

Whatever the purpose, you’ll declare your variables using this syntax:
<Type> <Variable Name>;

The type is either a primitive data type or the name of a class that you want to instantiate and use.

Primitive Data Types: Primitive data types are defined in the C language and are used to hold very basic values. Common types you’ll encounter include the following:

int: Integers (whole numbers such as 1, 0, and -99)
float: Floating-point numbers (numbers with decimal points in them)
double: Highly precise floating-point numbers that can handle a large number of digits

Object Data Types and Pointers: To declare a variable as an object of a specific class, we must declare the variable as a pointer to an object. A pointer references the place in memory where the object is stored, rather than a value. To declare a vari- able as a pointer, prefix the name of the variable with an asterisk. For example, to declare a variable of type NSString with the intention of holding a user’s name, we might type this:

NSString *userName;

Once declared, you can use the variable without the asterisk. It is only used in the declaration to identify the variable as a pointer to the object.

Allocating, Initializing, and Releasing Objects

Before an object can be used, memory must be allocated and the contents of the object initialized. This is handled by sending an alloc message to the class that you’re going to be using, followed by an init message to what is returned by alloc. The syntax you’ll use is this:

[[<class name> alloc] init];

For example, to declare and create a new instance of UILabel class, you could use the following code:

UILabel *myLabel;

myLabel=[[UILabel alloc] init];

Once allocated and initialized, the object is ready to use.

Convenience Methods: When we initialized the UILabel instance, we did create a usable object, but it doesn’t yet have any of the additional information that makes it useful. Properties such as what the label should say or where it should be shown on the screen have yet to be set. We would need to use several of the object’s other methods to really make use of the object.

Apple’s classes often provide a special initialization method called a convenience method. These methods can be invoked to setup an object with a basic set of properties so that it can be used almost immediately.

For example, the NSURL class, which you’ll be using later on to work with web addresses, defines a convenience method called initWithString. To declare and initialize an NSURL object that points to the website. we might type the following:

NSURL *iPhoneURL;
iPhoneURL=[[NSURL alloc] initWithString:@”http://www.teachyourselfiphone.com/”];

Without any additional work, we’ve allocated and initialized a URL with an actual web address in a single line of code.

Using Methods and Messaging: To send an object a message, give the name of the variable that is referencing the object followed by the name of the method—all within square brackets. If you’re using a class method, just provide the name of the class rather than a variable name:

[<object variable or class name> <method name>];

Things start to look a little more complicated when the method has parameters. A single parameter method call looks like this:

[<object variable> <method name>:<parameter value>];

An actual example of using a multiple parameter method looks like this:
NSString *userName;
[userName compare:@”John” options:NSCaseInsensitive];

Expressions and Decision Making: Every decision in an app boils down to a “yes” or “no” result based on evaluating a set of tests. These can be as simple as comparing two values, to something as complex as checking the results of a complicated mathematical calculation. The combination of tests used to make a decision is called an expression.

Making Decisions with if-then-else and switch Statements: The most common way of defining these different execution paths is with an if-then-else statement:

if (<expression>) {

// do this, the expression is true.

}

else {

// the expression isn’t true, do this instead!

}

For example, consider the comparison we used earlier to check a userName NSString variable to see whether its contents were set to a specific name. If we want to react to that comparison, we might write the following:

If ([userName compare:@”John”]) {

userMessage=@”I like your name”;

}

else {

userMessage=@”Your name isn’t John, but I still like it!”;

}

A switch statement checks a variable for a value, and then executes different blocks of code depending on the value that is found:

switch (<numeric value>) {

case <numeric option 1>:

// The value matches this option

break;

case <numeric option 2>:

// The value matches this option

break;

default:

// None of the options match the number.

}

Applying this to a situation where we might want to check a user’s age (stored in userAge) for some key milestones and then set an appropriate userMessage string if they are found, the result might look like this:

int userAge=18;
switch (userAge) {

case 18:

userMessage=@”Congratulations, you’re an adult!”;

break;

case 21:

userMessage=@”Congratulations, you can drink champagne!”;

break;

case 50:

userMessage=@”You’re half a century old!”;

break;

default:

userMessage=@”Sorry, there’s nothing special about your age.”;

}

Repetition with Loops: A loop defines the start and end of several lines of code. As long as the loop is running, the program executes the lines from top to bottom, and then restarts again from the top. The loops you’ll use are of two types: count-based and condition- based.

In a count-based loop, the statements are repeated a certain number of times. In a condition-based loop, an expression determines whether a loop should occur. The count-based loop you’ll be using is called a for loop, with this syntax:

for (<initialization>;<test condition>;<count update>) {

// Do this, over and over!

}

Example

int count;

for (count=0;count<50;count=count+1) {

// Do this, 50 times!

}

In a condition-based loop, the loop continues while an expression remains true. There are two variables of this loop type that you’ll encounter, while and do-while:

while (<expression>)

{

// Do this, over and over, while the expression is true!

}

and

do {

// Do this, over and over, while the expression is true!

} while (<expression>);

For example, suppose you are asking users to input their names and you want to keep prompting them until they type John. You might format a do-while loop like this:

do {

// Get the user’s input in this part of the loop

} while (![userName compare:@”John”]);

LINK+IMAGE

Writing Your First iPhone Program

noreply@blogger.com (Anonymous) — Sat, 09 Apr 2011 17:45:00 +0000

The Apple iPhone is becoming a full-fledged development platform. It's reliance on desktop- class operating system software is allowing it to become the most powerful mobile platform available. Here is how you can get in on the action, even if you have never written a line of code before! First, you need an Apple computer with an Intel processor and Mac OS X Leopard. I'm sure that Apple would be happy to help you with this step. We're going to jump right into making a program, but first we need to define a few terms.

Software Development Tools

Apple's IDE is called Xcode, and is available for free on Apple's software development website to anyone who registers as a developer. Apple has repackaged Xcode with iPhone development resources and called it the iPhone SDK.

Registering as a Developer and Downloading Xcode

Open your favorite web browser and go to http://developer.apple.com/iphone/program.
Scroll to the bottom of the page and click “Download the Free SDK”.
Click “Create Apple ID”.
Input your information and click “Create”.
In the downloads section, click “iPhone SDK”.

Installing Xcode

Double click the DMG and you will be presented with a window containing the Xcode installation package.
Double click iPhone SDK.
follow the installation instructions. The default
selections for each screen are fine.

Running Xcode

Because Xcode depends on many system-level services and includes many programs, it does not install into the Applications folder. To run Xcode and other tools thatcome with the iPhone SDK:

Double-click “Macintosh HD” on your desktop.
Double-click “Developer”
Double-click “Applications”
Double-click “Xcode”

Creating Your First Project

Xcode's user interface, like most Mac applications, is composed of many windows that are tied together with the main menu at the top of the screen. The first time Xcode is run, it will present a welcome screen. These screens can be helpful, but not at the moment. Close them and we will create your first iPhone project.

Click “File -> New Project”.
Click the “View-Based Application” icon.
Click “Choose”.
Navigate to a location where you would like to store
your iPhone projects. In the text box labeled “Save As:” type “HelloWorld”.
Click “Save”.

Writing and Compiling Your Program
The window you are seeing now is the main IDE program. It has the editor and controls for the compiler built into it. We will now add the code to create a button and a button action.

Expand the “Classes” group on the left side by clicking on the small triangle next to it.
Click on “HelloWorldViewController.m”.
Scroll down to the second green code region. This is a code comment showing where to put your code if you are creating your user interface using code.
Put the following Code in ViewDidLoad Method

Add This code to viewDidLoad method

- (void)viewDidLoad {
[super viewDidLoad];
UIButton* helloButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
helloButton.bounds = CGRectMake(0.0f, 0.0f, 200.0f, 50.0f);
helloButton.center = self.view.center;
helloButton.font = [UIFont boldSystemFontOfSize:30.0f];
[helloButton setTitle:@"Hello" forState:UIControlStateNormal];[helloButton addTarget:self action:@selector(helloButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:helloButton];
}

Add this Method to the file also

- (void) helloButtonPressed:(id)sender {
}
[(UIButton*)sender setTitle:@"Hello World!" forState:UIControlStateNormal];
}

Now Your Files Looks As

Running Your Program

Now we have some code written for the compiler to compile and the simulator to run. To compile your code and start the simulator running your program, press the “Build and Go” button at the top. If asked to save your changes, press “Save All”. The simulator will start up and run your program. Congratulations on writing your first iPhone program!