Programs ++

Basic OOP program

noreply@blogger.com (Fatal1ty) — Wed, 22 Aug 2012 05:25:00 +0000

Object Oriented Programming or OOP is an approach to programming(in general) that is based on the view of treating each entity or element as an object, in such a way that each object is unaware of the existence of other objects. Before going further, let me lay out some basic details for you.

CLASS - Many of you must have the definition of class as : "a class is the collection of data members of same or different type, grouped under a common name". Well this is actually a very trivial definition of class. A class serves as a blueprint for building something. Simply put, it is a layout that describes where everything should be put together. In programming

terminology, a class is a way of binding the data describing an entity and its associated functions together.

Now i can go on and on, about classes and object, why the use of classes, data abstraction and so on, but all that you can find in any textbook. Let us jump to the practical implementation of OOP.

The article follows a program that demonstrates the use of classes and objects. Before i get into the nitty gritty of it all, please understand that you need to focus on the concept , not the

technical details. The "TECH DETAILS" will come with time and practice. Focus must be on understanding the concept. So let's begin :

The following program creates a class "MarkSheet" with a single member variable "marks" of type int(a.k.a integer). Now the class also has two PUBLIC member functions, a setter function and a corresponding getter function. Getter and Setter functions are not some SPECIAL functions, they are just named that way, sort of a trend. The job of a "getter" function is to return

the value of a variable of the class and the job of a "setter" function is to SET the value of a variable of the class.

For e.g : here is a demo setter function

void setDAY(int x) // sets the value of 'day' with the value contained by 'x'

{

day = x;

}

Similarly, e.g : here is a demo getter function

int getDay() // 'gets' or returns the value of the variable 'day'

{

return day;

}

The class has the following setter and getter functions :

1 - setMarks() // sets the marks of the student

2 - getMarks() // gets or returns the marks of the student

In the main() function, two objects,name objA and objB are declared that represent object of student A and B respectively. The program then prompts the user to enter the values

of the marks of students A and B. The marks are set by using the setMarks() setter function. After that, the marks are displayed by calling the getMarks() getter function.

Note : Please do not get into the details of using 'this'. Just understand that 'this' acts as a pointer to the current object. To get more details on the use of 'this' in OOPS, please refer

the FAQ.

// C++ program to demonstrate the concept of Object Oriented Programming Structure(OOPS)

#include<iostream>

using namespace std;

class MarkSheet
{
     int marks;

     public :

     void setMarks(int marks) // setter function
     {
          this->marks = marks;
     }

     int getMarks() // getter function
     {
          return this->marks;
     }

}; // end of class MarkSheet

int main()
{
     MarkSheet objA; // object A of class MarkSheet
     MarkSheet objB; // object B of class MarkSheet
     int temp;

     // propmts the user to enter the marks of student A
     cout<<" Enter the marks of student A : ";
     cin>>temp;
     objA.setMarks(temp); // uses the setter function to set the marks of student A

     // propmts user to enter the marks of student B
     cout<<" Enter the marks of student B : ";
     cin>>temp;
     objB.setMarks(temp); // uses the setter function to set the marks of student B

     cout<<"\n ---------- Marks of A and B are as follows ------------ \n";
     cout<<" Marks of student A : "<<objA.getMarks(); // displays the marks of student A
     cout<<"\n Marks of student B : "<<objB.getMarks(); // displays the marks of student B
     return 0;
}// end of main

------ OUTPUT -----

Use of string iterator in C++

noreply@blogger.com (Fatal1ty) — Tue, 22 May 2012 16:23:00 +0000

The following program computes the length of the string using the string iterator

// Program to demonstrate the use of string iterator
#include <iostream>
#include <string>

int main()
{
     using namespace std;
     int counter=0;
     string str("welcome to programsplusplus");
     // declares the string iterator
     string::iterator it;
     for (it=str.begin(); it<str.end(); it++)
     {
          // displays each character that the iterator points to
          counter++;
          cout<<" "<<*it;
     }
     cout<<"\n"<<"Total length of the string : "<<counter;

     return 0;
} // end of main
------OUTPUT------

Methods to initialize string in C++

noreply@blogger.com (Fatal1ty) — Mon, 21 May 2012 17:20:00 +0000

// Various methods to initialize strings in C++

#include <iostream>
#include <string>

using namespace std;

int main()
{
     string s0("welcome to programsplusplus");
     string s1(s0);
     std::cout<<s1;

     string s2(s0,8,3);
     std::cout<<"\n"<<s2;

     string s4("hello world",4);
     std::cout<<"\n"<<s4;

     string s5(10,'x');
     std::cout<<"\n"<<s5;

     string s6(10,42);
     std::cout<<"\n"<<s6;

     string s7(s0.begin(),s0.begin()+5);
     std::cout<<"\n"<<s7;

     return 0;
}

------ OUTPUT------

C++ implementation of linked list

noreply@blogger.com (Fatal1ty) — Sun, 20 May 2012 06:53:00 +0000

// C++ implementation of a linked list

#include <iostream>

struct Node // declares the node structure
{
     int info;
     Node *next;
}*start,*ptr,*newptr;

Node *new_list(int x) // creates a new list
{
     ptr = new Node;
     ptr->info = x;
     ptr->next = NULL;
     return ptr;
}

void insert_beg(Node *np) // inserts an element in list
{
     if ( start == NULL )
          start = np;
     else
     {
          Node *save = new Node;
          save = start;
          start = np;
          np->next = save;
     }
}

void display(Node *np) // displays the list
{
     while ( np != NULL )
     {
          std::cout<<np->info<<" -> ";
          np = np->next;
     }
}

int main()
{
     int item,choice;
     do
     {
          std::cout<<" \n1 : Create a new list ";
          std::cout<<" \n2 : Insert at beginning ";
          std::cout<<" \n3 : Display List ";
          std::cout<<" \n4 : Exit\n ";
          std::cout<<"\n Enter your choide : ";
          std::cin>>choice;

          switch(choice)
          {
               case 1 :
                    std::cout<<" \nEnter some value : ";
                    std::cin>>item;
                    start = new_list(item);
                    std::cout<<" List created !!! ";
                    break;
               case 2 :
                    std::cout<<" Enter an item to insert : ";
                    std::cin>>item;
                    newptr = new Node;
                    newptr->info = item;
                    newptr->next = NULL;
                    insert_beg(newptr);
                    break;
               case 3 :
                    std::cout<<" The list is as follows : \n";
                    display(start);
                    break;
          } // end of switch

     }while ( choice != 4 ); // end of do while
     return 0;
}// end of main

------OUTPUT------

Namespace example in C++

noreply@blogger.com (Fatal1ty) — Fri, 04 May 2012 15:25:00 +0000

// Program to demonstrate the use of namespaces

#include <iostream>

namespace other // defines a namesapce
{
          int sum(int,int); // function prototype
}

// function sum() that belong to the other namespace which returns the sum of two //integers
int other :: sum(int x,int y)
{     return x+y;
}
/* another function sum() that does not belong to the namespace 'other' and returns the
   difference of two integers passed as arguments */
int sum(int x,int y)
{   return x-y;
}

int main()
{
    int a,b;
    // prompts the user to enter two integer values a and b
    std::cout<<" Enter the value of a : ";
    std::cin>>a;
    std::cout<<" Enter the value of b : ";
    std::cin>>b;
    // calls the function declared under the 'other' namespace
    // notice the other:: is used to call this function
    std::cout<<"\n Sum() function of 'other' namespace : "<<other::sum(a,b);
    // normal sum() function that actually computes the difference of a and b
    std::cout<<"\n Normal Sum() function : "<<sum(a,b);
    return 0;
}// end of main

------ OUTPUT ------

C++ program to display current date and time

noreply@blogger.com (Fatal1ty) — Sat, 28 Apr 2012 09:40:00 +0000

This program is about printing the date and time using C++. The C library contains the time.h header that deals with time and dates. Before heading further, i would like to mention a new type of variable of the type time. It is the time_t type, which is a variable of time and is used to store time related information when dealing with time functions included in the time.h header file.

It is declared as follows :

time_t seconds; // this declares a variable of the type time_t

Please note that it is not a fundamental data type;

Now, to print the date and time, we need to store it first. This task is done with the time() function, that calculates the time and stores it in a variable of type time_t. The value that is calculated is a long numeric value. To print the date and time in a more readable and user friendly format, the ctime() function is used which converts the date and time into a string for display purposes.

The program below demonstrates the use of time() and ctime() functions to display time and date. It also displays the time elapsed from 1st January 1970 till now. For more information, please e-mail me or leave a comment.

// Program to print current date and time using C++

#include <iostream>
#include <ctime>

int main()
{
     time_t sec;
     // creates and instance of the time variable time_t
     time(&sec);
     std::cout<<" Current Date and time : "<<ctime(&sec);
     std::cout<<"\n Time elapsed from 1st January 1970 --> "<<sec<<" seconds ";
     std::cout<<"\n Time elapsed from 1st January 1970 --> "<<sec/3600<<" hours ";
     std::cout<<"\n Time elapsed from 1st January 1970 --> "<<(sec/3600)/24<<" days ";
     std::cout<<"\n Time elapsed from 1st January 1970 --> "<<((sec/3600)/24)/7<<" weeks ";
     std::cout<<"\n Time elapsed form 1st Jaunary 1970 --> "<<((sec/3600)/24)/365<<" years ";
     std::cout<<"\n Time elapsed from 1st January 1970 --> "<<(float)(((sec/3600)/24)/365)/10<<" decades \n";
     return 0;
} // end of main

------ OUTPUT ------

Matrix Multiplication in C++

noreply@blogger.com (Fatal1ty) — Fri, 20 Apr 2012 15:57:00 +0000

Matrix multiplication is one of the most basic programs I learned when i was in my 12th standard. Its really simple, simply multiply the rows
of the 1st matrix with the columns of the 2nd matrix and add them up. This will generate the resultant matrix.

The following code demonstrates how it is done. Read it, its quite simple. Still if you encounter any problems or have any other query, please
leave a comment or email me. Any suggestions are also welcome

// Program to multiply two matrices

#include <iostream>

int main()
{
     int arr1[20][20],arr2[10][10];
     int result[20][20];
     int m,n;
     int i,j;
     // prompts the user to enter the rows and columns of the matrix
     std::cout<<" Enter the number of rows (m) : ";
     std::cin>>m;
     std::cout<<" Enter the number of columns (n) : ";
     std::cin>>n;
     std::cout<<" \n Enter the elements of the 1st matrix \n ";

     for (i=0; i<m; i++)
     {
          for (j=0; j<n; j++)
          {
               std::cout<<" Element "<<i<<" : "<<j<<" --> ";
               std::cin>>arr1[i][j];
          }
     }

     std::cout<<"\n Enter the elements of the 2nd matrix : \n ";
     for (i=0; i<m; i++)
     {
          for (j=0; j<n; j++)
          {
               std::cout<<" Element "<<i<<" : "<<j<<" --> ";
               std::cin>>arr2[i][j];
          }
     }

     //------------ display matrics -----------------------

     std::cout<<"\n 1st matrix \n ";
     for (i=0; i<m; i++)
     {
          for (j=0; j<n; j++)
          {
               std::cout<<" "<<arr1[i][j];
          }
          std::cout<<"\n";
     }

     std::cout<<"\n 2nd matrix \n ";
     for (i=0; i<m; i++)
     {
          for (j=0; j<n;j++)
          {
               std::cout<<" "<<arr2[i][j];
          }
          std::cout<<"\n";
     }
    std::cout<<" \n Resultatn matrix \n";
    int k=0;
     // multiplies the two matrices together
     for(i=0;i< m;i++)
     {
          for(j=0;j< n;j++)
          {
               result[i][j] = 0;
          for(k=0;k< m;k++)
          {
               result[i][j] = result[i][j] + arr1[i][k] * arr2[k][j];
          }
          } // end of j sub loop
     } // end of i main loop

     // displays the resultant matrix

     for (i=0; i<m; i++)
     {
          for (j=0; j<n; j++)
          {
               std::cout<<result[i][j]<<" ";
          }
          std::cout<<"\n \n";
     }
     return 0;
} // end of main

------ OUTPUT ------

Reverse of an integer in C++

noreply@blogger.com (Fatal1ty) — Tue, 17 Apr 2012 15:23:00 +0000

The modulus operator (%) is widely used in many programming languages, especially in C/C++. It returns the remainder. For e.g 10%2 returns 0 as the remainder that we get when dividing 10 by 2 is 0.

One use of this operator is used for finding the reverse of an integer. Simply divide the integer by 10 and use the modulus operator to store
the remainder. The following programs demonstrates the above concept.

// Program to find out the reverse of an integer

#include <iostream>

int main()
{
     unsigned int x;
     // prompts the user to enter an integer
     std::cout<<" Enter the number : ";
     std::cin>>x;
     std::cout<<" The reverse of "<<x<<" is : ";
     while ( x != 0)
     {
          std::cout<<x%10;
          x = x/10;
     }
     return 0;
}// end of main

------ OUTPUT ------

Sophie Germain Prime Numbers in C++

noreply@blogger.com (Fatal1ty) — Wed, 04 Apr 2012 15:50:00 +0000

Prime numbers are those numbers that are only divisible by 1 and themselves. Sophie geramin prime numbers are a special category of prime numbers.
By definition, a prime number, say 'p', is a sophie germain prime number if p is prime and 2p+1 is also prime. For e.g 23 is a sophie germain prime because
23 is prime and 23*2 + 1 = 47 is also prime.

For those who do not know how to check whether a number is prime or not, please read my post : Checking PRIME numbers in C++.

Now generating sophie germain primes, is actually quite a simple task. We need just need to check the following :
1 - p is prime
2 - 2p+1 is prime
3 - print p if both cases 1 and 2 turn out to be true.

The following program generates sophie germain primes upto the limit specified by the user. Please have a look at the source code to have a better
understanding of how the program works. Please leave a comment if you want to ask something or just want to say hi .

// Program to generate sophie germain prime numbers

#include <iostream>

bool checkPrime(int number)
{
     bool flag = true;
     if ( number == 2 ) // checks if 2 is entered(as 2 is a prime number )
     {
      //    std::cout<<" The number is PRIME !!! ";
          return true; // terminates the program is two is enterd, as there is no need for further checking
     }

     else // divides the number with value from 2 to (number-1)
     {
          for (int i=2; i<number; i++)
          {
               // if it is divisible than values smaller than number-1 it is non - prime
               if ( number%i == 0)
                    flag = false;
          }
     }
     return flag; // returns either true or false as the result

}

int main()
{
     int max,i = 2;
     // prompts the user to enter the max numbers to generate
     std::cout<<" Enter the max. numbers to generate : ";
     std::cin>>max;
     int counter = 1;

     while ( counter <= max) // run until the limit is reached
     {
          if ( checkPrime(i) == true ) // initial check to see if p is prime
          {
               if ( checkPrime((2*i) + 1) == true ) // secondary check to see if 2p+1 is prime
               {
                    std::cout<<" "<<i; // displays the number if it turns out to be a sophie germain prime
                    counter++;
               }
          }
          i++;
     } // end of while
     std::cout<<"\n End of program !! ";
     return 0;
} // end of main

------ OUTPUT ------

1 : For more information on sophie germain primes , please visit : http://en.wikipedia.org/wiki/Sophie_Germain_prime

2 : Checking Prime numbers in C++ : http://programsplusplus.blogspot.in/2012/03/c-program-to-check-prime-numbers.html

3 : Generating Prime numbers in C++ : http://programsplusplus.blogspot.in/2012/03/numbers-can-become-quite-huge-mess-when.html

Constructer initialization

noreply@blogger.com (Fatal1ty) — Tue, 03 Apr 2012 15:20:00 +0000

Initializing variables while writing a program is one of the most basic routines that a programmer does while writing the code. Normally it is done using the assignment operator '=' and initializing the variable.
E.g

int x = 5;

// this initializes the value of x with 5

But i found out that it could also be done this way,

int x(5); // this initializes the variable with the value 5

This is called constructor initialization, though it is not widely used, I thought it would be a good idea to know.

Initializing the variable using this method has no advantage, so its not necessary. Just remember that it can also be done this way.

Binary to Decimal conversion in C++

noreply@blogger.com (Fatal1ty) — Mon, 02 Apr 2012 16:25:00 +0000

My previous post was based on converting a decimal number into its binary equivalent. Contrary to that, the program given below converts binary numbers into their decimal equivalents. That is, it converts binary numbers such as 1000 into its corresponding decimal equivalent i.e 8.

Now for those who are not familiar with the concept of binary numbers, please read the following post : decimal to binary conversion.
Now, the method works like this. Just traverse the binary number step by step, starting from 0 to n-1, where n is the most significant bit(MSB) ,
multiply them with 2 with raising powers and add the sum together. E.g to convert 1000(which is binary equivalent of 8), just do the following

1 0 0 0 ==> going from right to left

0 x 2^0 = 0
0 x 2^1 = 0;
0 x 2^2 = 0;
1 x 2^3 = 8;

now add them together i.e 0+0+0+8 = 8; this the decimal equivalent of 1000. Please read the program below to have a better understanding how the concept
work. Note : The program works only for 16-bit binary numbers(non-floating) or less. Leave a comment if anything is not clear. You are bound to receive a reply.

// Program to convert binary to its decimal equivalent

#include <iostream>
#include <math.h>

int main()
{
     int x;
     int i=0,sum = 0;
     // prompts the user to input a 16-bit binary number
     std::cout<<" Enter the binary number (16-bit) : ";
     std::cin>>x;

     while ( i != 16 ) // runs 16 times
     {
          sum += (x%10) * pow(2,i);
          x = x/10;
          i++;
     }
     std::cout<<"\n The decimal equivalent is : "<<sum;
     return 0;
}

------ OUTPUT ------

------ Programming Advice and Tips ------

1 : Note : The above program only accepts 16-bit binary numbers as inputs. This limit can be increased by increasing the number of loop executions by
changing the value in the while loop from 16 to say 32. (be sure it is a valid number which is a factor of 2 ).

2 : This program is the most basic method to do this type of conversion. However, there are a number of algorithms to do the same, so just GOOGLE out some
of them. Try it out, there are a variety of programs that do the same conversion in different ways.

Please do comment if you don't understand any part or want to know more or just want to say thanks. I love programming and love to teach my friends. Your suggestions and appreciation will make this blog much better.

------ Related Posts ------

1 : Decimal to binary conversion (v1.0) : http://programsplusplus.blogspot.in/2012/04/my-apologies-to-my-readers-for-posting.html
2 : Decimal to binart conversion (v2.0) : http://programsplusplus.blogspot.in/2012/04/decimal-to-binary-conversion-program.html

Decimal to Binary conversion program (v2.0)

noreply@blogger.com (Fatal1ty) — Sun, 01 Apr 2012 15:56:00 +0000

The program I posted in my previous post could only convert whole decimal numbers into binary. Meaning it could not convert decimal numbers like 2.34 into its binary equivalent. This is the updated version of that program, and this one is capable of converting any decimal number into its binary equivalent.

Pleas read the post : Decimal to binary conversion , if you are new to this concept.

// Program to convert decimal to binary ( version 2.0 )

#include <iostream>

void convert_integer(int arr[],int x) // function to convert the integer part to binary
{
     int i=0;
     while ( x != 0 ) // until x is fully divided, leaving only 1
     {
          arr[i] = x%2; // store the remainder in the array
          x = x/2;
          i++;
     }
     /*since arrays are passed by refernce, hence any changes in the parameter array will
        result in change in the array passed as the argument */

} // end of function

void convert_float(int arr[],double x) // function to convert the floating part into binary
{
     int i=0;
     do
     {
          x = x * 2;
          if ( x > 1 )
          {
               arr[i] = (int)x;
               x = x - (int)x;
          }
          else
          arr[i] = (int)x;
          i++;
     }while ( x != 1 && i != 8);

}// end of function

int main()
{
     double value;
     int arr1[8] = {0,0,0,0,0,0,0,0}; // for integral part
     int arr2[8] = {0,0,0,0,0,0,0,0}; // for floating part
     std::cout<<" Enter a number to convert : ";
     std::cin>>value;
     convert_integer(arr1,(int)value);
     double temp = value - (int)value;
     convert_float(arr2,temp);

     std::cout<<" \n The binary output (8-bit ) is : ";

     for (int i=7; i>=0; i--) // displays the LHS of the binary number
          std::cout<<arr1[i]<<" ";

     std::cout<<" . "; // adds the decimal(point) between the numbers

     for (int i=0; i<8; i++) // displays the RHS of the binary number
          std::cout<<arr2[i]<<" ";

     return 0;
} // end of main

------ OUTPUT ------

------ Related Posts ------

1 : Decimal to binary conversion (v1.0) : http://programsplusplus.blogspot.in/2012/04/my-apologies-to-my-readers-for-posting.html
2 : Binary to decimal conversion : http://programsplusplus.blogspot.in/2012/04/binary-to-decimal-conversion-in-c.html

Decimal to Binary Conversion Program

noreply@blogger.com (Fatal1ty) — Sun, 01 Apr 2012 05:41:00 +0000

My apologies to my readers for posting after such a long time. Had been caught up in examinations...!!

Anyways, this is a simple program to convert decimal numbers to binary numbers. In computers , binary numbers form the base of everything. Even numbers like 10,3,5 etc are converted into long string of 0s and 1s. For e.g. the decimal number 8 is converted into 1000. The bigger the number, the more 0s and 1s it has. Hence it makes sense to have a useful program to convert decimal numbers to binary numbers.

The program given below does that particular task. It takes in a decimal whole number and converts it into its binary equivalent.

The conversion method is quite simple. Just divide the number by 2 recursively and store its remainder side by side. Here is how the program works :

Step 1 : The program prompts the user to enter a decimal number;

Step 2 : The number is divided by 2 and its remainder stored in an array.

Step 3 : The number itself is divided by 2.

Step 4 : The loop is run backwards, and this gives us the required binary equivalent.

Read the following code for a better understanding.

// Program to convert decimal to binary (8-bit)

#include <iostream>

int main()

{

int arr[8] = {0,0,0,0,0,0,0,0}; // for a 8 bit binary

int x;

std::cout<<" Enter the value to compute (integer only) : ";

std::cin>>x;

int i=0;

while ( x != 0 )

{

arr[i] = x%2;

x = x/2;

i++;

}

std::cout<<" \n Binary Output (8-bit) : ";

for (i=7; i>=0; i--)

std::cout<<arr[i]<<" ";

return 0;

} // end of main

------ OUTPUT ------

------ Programming Advice and Tips ------

1 : The above program generates an 8 bit binary number. If you want a higher bit binary number, suppose 16-bit, then simply increase the size of the array fro
8 to 16 and initialize it accordingly.
2 : Be careful during display of the binary equivalent, keep in mind that the array has to be traversed in a descending index order i.e backwards, otherwise you
will not get the proper result.
3 : You can use the above program to convert decimal numbers into other types of numbers ( for e.g octal(base 8), just divide the number by 8.)
4 : Contact me at : programsplusplus@gmail.com for related queries or leave a comment....you are bound to receive an answer.

-----

C++ program to check PRIME numbers

noreply@blogger.com (Fatal1ty) — Thu, 08 Mar 2012 06:57:00 +0000

My previous post was about prime numbers and demonstrated a program to generate them in C++ . This post is about finding whether a number is prime or not. Now as stated earlier, prime numbers are only divisible by the number 1 and themselves, and we will be using this particular property to find whether a number is prime or not. Please read the post Prime number generation in C++ for more information on prime numbers and how to generate them.

The method is simple, divide the prime number by integers ranging from 2 to number-1. If the division generates a whole number(that is remainder is 0), then it is not a prime number, as they are only divisible by themselves(and 1) and not by any other number.

For e.g if we want to check whether 5 is a prime number or not(which it is :p ), we simply divide 5 by numbers less than 5 i.e 2,3,4 . Since the division will not generate a whole number, hence it is a prime number. In the language of coding, simply run a loop from 2 to number-1 and divide it with the number itself. If the remainder is 0 then it is not a prime no. If it is 1 then it is a prime number. Simple !! :)

The following program demonstrates the above method :

// Program to check whether a given integer is prime or not

#include <iostream>

#include <iomanip> // for exit() function

int main()

{

int number;

bool flag = false;

// prompts the user to enter a value to test for prime property

std::cout<<" Enter the number to test : ";

std::cin>>number;

if ( number == 2 ) // checks if 2 is entered(as 2 is a prime number )

{

std::cout<<" The number is PRIME !!! ";

exit(true); // terminates the program is two is enterd, as there is no need for further checking

}

else // divides the number with value from 2 to (number-1)

{

for (int i=2; i<number; i++)

{

// if it is divisible than values smaller than number-1 it is non - prime

if ( number%i == 0)

flag = false;

}

// prints the correct message based on the flag value

if ( flag == true )

std::cout<<" \n The number is NON-PRIME !!!";

else

std::cout<<"\n The number is PRIME !!! ";

return 0;

} //end of main

------ OUTPUT ------

------ Some Facts ------

The only even prime number is 2. All other even numbers can be divided by 2.
If the sum of a number's digits is a multiple of 3, that number can be divided by 3.
No prime number greater than 5 ends in a 5. Any number greater than 5 that ends in a 5 can be divided by 5.
Zero and 1 are not considered prime numbers.
Except for 0 and 1, a number is either a prime number or a composite number. A composite number is defined as any number, greater than 1, that is not prime.

------ Related Posts ------

1 - Prime number generation in C++ : http://programsplusplus.blogspot.in/2012/03/numbers-can-become-quite-huge-mess-when.html

2 - Prime number theorem : http://mathworld.wolfram.com/PrimeNumberTheorem.html
3 - Fibonacci series in C++ : http://programsplusplus.blogspot.in/2012/03/fibonacci-series-in-c.html

Prime number generation in C++

noreply@blogger.com (Fatal1ty) — Wed, 07 Mar 2012 16:34:00 +0000

Numbers can become quite a huge mess when it comes to generating a particular type of series :p. Many number series such as prime numbers and the famous Fibonacci series are widely taught to C++ beginners. My previous post was related to Fibonacci series so i thought it be a good idea to write something on prime numbers.

Now, for those who don't really know :P, prime numbers are basically numbers that are only divisible by 1 and themselves.
For e.g 23 is a prime number as it is divisible only by 1 and itself. Some prime numbers are as follows :
2 3 5 7 11 13 17 19 23 31 37 41.....so on. Notice that most of the prime numbers greater that 2 are odd. This is also a
notable property of prime numbers.

However, the question is this ...HOW TO GENERATE THEM ???? It seems that there is no exact formula to generate all the
prime numbers. But by using simple loops , we can generate them in C++. :) The program given below shows how :

// Program to generate prime numbers in C++

#include <iostream>

int main()
{
     int max;
     // prompts the user to enter the range in which to generate
     std::cout<<" Enter the upper range ? : ";
     std::cin>>max;

     for (int n=2; n<max; n++) // main loop
     {
          int flag = 0;
          // loop to check whether a numbers is prime or not
          for (int i=2; i<=n/2; i++)
               if ( n%i == 0 )
               {
                    flag = 1;
                    break;
               }
               if ( flag == 0 )
               {
                    std::cout<<" "<<n;
               }
     } // end of main loop
     return 0;
} // end of main

------ OUTPUT ------

------ Programming advice and Tips ------

1 - There are numerous ways to generate prime numbers, you can find a lot of algorithms simply use our holy grail of search engines, GOOGLE. !!!

2 - Many algorithms use have different complexity and vary on speed, complexity and limitations. So choose what suits you best.

Please do comment if you don't understand any part or want to know more or just want to say thanks. I love programming and love to teach my friends. Your suggestions and appreciation will make this blog much better.

------ Related Posts ------

1 : Fibonacci series in C++ : http://programsplusplus.blogspot.in/2012/03/fibonacci-series-in-c.html
2 : Sieve of Eratosthenes algorithm to generate prime numbers ( for all programming languages ) : http://rosettacode.org/wiki/Sieve_of_Eratosthenes#C.2B.2B
3 : Prime Number Theorem : http://en.wikipedia.org/wiki/Prime_number_theorem
4 : Checking whether a number is prime or non-prime : http://programsplusplus.blogspot.in/2012/03/c-program-to-check-prime-numbers.html

Fibonacci Series in C++

noreply@blogger.com (Fatal1ty) — Tue, 06 Mar 2012 15:34:00 +0000

The Fibonacci series is a very popular series and has many applications in many fields from mathematics to biology.
The series is as follows : 1 1 2 3 5 8 13..... There are also negafibonacci number series which are have negative value.
Now, observe carefully, we see that each number in the Fibonacci series is the sum of the preceding two number and here
lies the method to generate them using C++. Simply add the two preceeding numbers and store them inside an array.
for e.g to generate 1 1 2 3 5, simply,
add 1,1 --> 1+1 = 2, and store it.
then again add 2,1 --> 2+1 = 3 ,and store it.
and, finally add 3,2 --> 3+1 = 5 ,and store it.
The following program demonstrates the concept.
// Program to print a sequence of fibonacci series
#include <iostream>

int main()
{
     int max,i=0,j=0;
     int temp;
     int arr[50];
     // prompts the user to enter the limit
     std::cout<<" Numbers to generate (max 50) ? : ";
     std::cin>>max;
     // initializes first two indexes with 1
     arr[0] = 1;
     arr[1] = 1;
     for (i=0; i<max; i++)
     {
          temp = arr[i] + arr[i+1];
          j = i+2;
          arr[j] = temp;
     }
     std::cout<<std::endl;
     // to display the fibonacci series
     for (i=0; i<max; i++)
     {
          std::cout<<" "<<arr[i];
     }
     return 0;
} // end of main

There are a numbers of ways to generate Fibonacci series, for more information please visit
http://en.wikipedia.org/wiki/Fibonacci_number

Please do comment if you don't understand any part or want to know more or just want to say thanks. I love programming and love to teach my friends. Your suggestions and appreciation will make this blog much better.

Factorial program in C++

noreply@blogger.com (Fatal1ty) — Tue, 06 Mar 2012 12:45:00 +0000

Calculating factorial is one of the most basic programs in did when i was learning C++ in 12th. :) Its quite a simple program actually, just decrement the number and multiply it with itself. Anyways C++ rookies will find this program on calculating factorial handy, since it is a part of their lab syllabus. The program below calculates the factorial of integers as well as decimal points .

// Program to calculate the factorial of a number
#include<iostream>

int main()
{
     double number;
     double result = 1.0;
     std::cout<<" Enter the number : ";
     std::cin>>number;
     for (double i=number; i>0.0; i--)
     {
          result *= i; // translates to result = result * i;
     }
     std::cout<<"\n The factorial is : "<<result;
     return 0;
} // end of main

------ OUTPUT ------

Counting number of words in a string

noreply@blogger.com (Fatal1ty) — Thu, 01 Mar 2012 16:01:00 +0000

This program is used to find the number of words in a string. Now, to do this is actually very simple.
Simply count the number of spaces between words. To do this, simply traverse the string using a loop and
increment a counter variable whenever a space character occurs. Simple :) .!! Do not forget to initialize the
counter variable !!!
Here is the source code :

// Program to count the number of words in a string
#include <iostream>

int main()
{
     char string[50];
     int counter = 1;
     // prompts the user to enter a string
     std::cout<<" Enter the string ( max 50chars ) : ";
     std::cin.getline(string,sizeof(string));

     for (int i=0; string[i]!= '\0'; i++ )
     {
          if ( string[i] == ' ' )
               counter++;
     }
     std::cout<<"\n Number of Words are : "<<counter;
     return 0;

} // end of main

------ OUTPUT ------

------ Related Posts ------

Converting a string to uppercase : http://programsplusplus.blogspot.in/2012/02/converting-array-of-string-to-uppercase.html

Selection sort in C++

noreply@blogger.com (Fatal1ty) — Mon, 27 Feb 2012 15:14:00 +0000

One family of internal sorting algorithms is selection sort. The basic idea of selection sort is to repeatedly select the smallest key in the remaining unsorted array. Simply put, an element is taken as the smallest key element
and then it is compared with the other elements to sort the array. It is implemented in the form of exchange selection sort that requires a single array to work with. In this technique, computer keeps on finding the next smallest element and brings it at its appropriate positions.
Selection sort can be used to sort an array in both ascending as well as descending order. The following program demonstrates
the implementation of selection sort in ascending order :

// Program to implement selection sort in C++ ( ascending order )

#include <iostream>

void selectionSort(int AR[],int size)
{
     int i,j,temp;
     for (i=0; i<size; i++)
     {
          for (j=i+1; j<=size; j++)
          {
               if ( AR[i] > AR[j] ) // sorts in ascending order
               {
                    temp = AR[j];
                    AR[j] = AR[i];
                    AR[i] = temp;
               }
          } // end of sub loop
     } // end of main loop

} // end of function selectionSort

int main()
{
     int arr[20],size;
     // prompts the user to enter the elements in the array
     std::cout<<" Enter the no. of elements that you want to enter (max 20 ) : ";
     std::cin>>size;
     std::cout<<" Now enter the elements in the array ";
     for (int i=0; i<size; i++)
     {
          std::cout<<" \n Element "<<i<<" : ";
          std::cin>>arr[i];
     }
     selectionSort(arr,size); // calls the function to sort the array
     std::cout<<" \n The sorted array is as follows ";
     for (int i=0; i<size; i++)
     {
          std::cout<<" \n Element "<<i<<" : "<<arr[i];
     }
     return 0;
} // end of main

------ OUTPUT ------

Please do comment if you don't understand any part or want to know more or just want to say thanks. I love programming and love to teach my friends. Your suggestions and appreciation will make this blog much better.

------ Related Posts ------
Bubble Sort in C++ : http://programsplusplus.blogspot.in/2012/02/bubble-sort-in-c.html
Insertion Sort in C++ : http://programsplusplus.blogspot.in/2012/02/insertion-sort-in-c.html

Insertion sort in C++

noreply@blogger.com (Fatal1ty) — Mon, 20 Feb 2012 16:03:00 +0000

Insertion sort is another sorting technique used when sorting arrays. Unlike bubble sort, it uses much less number of passes to sort an array. As the name suggests, sorting is done by inserting elements in their proper order by comparing an element with the elements on either side. Hers is how it works. Suppose we want to sort an array A with elements A[1],A[2]....A[N]. Then,
Step 1 : A[1] by itself is trivially sorted.
Step 2 : A[2] is inserted either before or after A[1] so that A[1],A[2] are sorted.
Step 3 : A[3] is inserted into proper place in A[1],A[2],that is, before A[1], between A[1]
and A[2, or after A[2], so that A[1],A[2],A[3] is sorted.
The process keeps repeating until the array is fully sorted.

The following program demonstrates the use of insertion sort by sorting an array of integers in ascending order

// Program to implement insertion sort ( ascending order )
#include <iostream>

void Insertion_sort(int AR[],int n)
{
     int temp,j;
     AR[0] = INT_MIN;
     for (int i=1; i<=n; i++)
     {
          temp = AR[i];
          j = i-1;
          while ( temp < AR[j])
          {
               AR[j+1] = AR[j];
               j--;
          }
          AR[j+1] = temp;
     } // end of for loop
} // end of insertion sort function

int main()
{
     int arr[20];
     int size;
     std::cout<<" Enter the maximum no. of elements you want (max 20) : ";
     std::cin>>size;
     std::cout<<"\n Now enter the elements in the array \n ";
     // loop to prompt the user to enter the elements in the array
     // notice that the elements are inserted fromt he 1st index rather that 0, as 0 index will be assigned
     // INT_MIN value from which other elements will be compared
     for (int i=1; i<=size; i++)
     {
          std::cout<<"Element "<<i<<" : ";
          std::cin>>arr[i];
     }
     Insertion_sort(arr,size);
     // as arrays are passed with reference, hence any changes will be reflected in the original array as well
     std::cout<<" \n The sorted array is as follows \n ";
     for (int i=1; i<=size; i++)
     {
          std::cout<<" \n Element "<<i<<" : "<<arr[i];
     }
     return 0;
} // end of main
------ OUTPUT ------

------Programming Advice and Tips------

1 - Even though insertion sort uses considerably less number of passes to sort an array, it still is not useful

when sorting arrays that contain large number of elements. Hence it is best advised to use insertion sort

where the no of elements to be sorted are less(i.e having small value of N).

2 - Notice that all the loops start from index location 1 rather than starting from 0 (which is usually done). This is done because, at the 0th index location, INT_MIN value is stored from which other elements are compared and is vital in terminating the while loop.

3 - INT_MIN is the MINIMUM value that an integer can have. It is usually a negative value, and varies from platform to platform.

Please do comment if you don't understand any part or want to know more or just want to say thanks. I love programming and love to teach my friends. Your suggestions and appreciation will make this blog much better.

------ Related Posts ------

Bubble Sort in C++ : http://programsplusplus.blogspot.in/2012/02/bubble-sort-in-c.html
Selection Sort in C++ : http://programsplusplus.blogspot.in/2012/02/selection-sort-in-c.html

Converting an array of string to uppercase

noreply@blogger.com (Fatal1ty) — Sat, 18 Feb 2012 05:25:00 +0000

Here is a program to convert an array of string into uppercase. Just like a recent post : "lowercase to uppercase" the following program also uses the standard C++ functions such as toupper() to convert string from lowercase to uppercase.

Now, the process is the same as converting a single string, traversing the entire string using a loop and converting each
character from lowercase to uppercase(or vice-verse) using toupper() (or tolower() ) and storing the converted characters
into another string.

The only difference that comes in an array of strings is that a loop has to be used to process individual strings sorted in the
array.Consider the string as columns of students in a classroom with each of the student sitting in the front desk as the
starting index of that column.

NOTE : be sure to add a terminating null character ('\0') at the end of each converted string, as this is not done by default by the
toupper() function !!!! :O

Here is an sample program.

// Program to convert an array of string to uppercase

#include <iostream>
#include <cctype>

int main()
{
     char name[5][20];
     char temp[5][20];
     int size;
     // prompts the user to enter the no. of string he/she wants in the array
     std::cout<<" Enter the no. of names you want to insert (max 5 ) : ";
     std::cin>>size;
     std::cin.ignore(); // to clear the memory buffer
     std::cout<<" \n Now enter the names (max 20 characters long ) : \n ";
     for (int i=0; i<size; i++)
     {
          std::cout<<" Name "<<i<<" : ";
          std::cin.getline(name[i],sizeof(name[i]));
     }
     // to convert them into uppercase
     int j=0;

     for (int i=0; i<size; i++) // main loop to traverse the rows
     {
          for (j=0; name[i][j] != '\0'; j++) // sub loop to traverse the individual strings
          {
               temp[i][j] = toupper(name[i][j]); // converts each character to uppercase
          }
          temp[i][j] = '\0'; // adds a terminating null character at the end of each string

     }
     // to show the names in uppercase

     for (int i=0; i<size; i++)
     {
          std::cout<<"\n NAME "<<i<<" : "<<temp[i];
     }
     return 0;
} // end of main

------ OUTPUT ------

Please do comment if you don't understand any part or want to know more or just want to say thanks. I love programming and love to teach my friends. Your suggestions and appreciation will make this blog much better.

------ Related Posts ------
Lowercase to Uppercsae : http://programsplusplus.blogspot.in/2012/01/lowercase-to-uppercase.html

Uppercase to Lowercase : http://programsplusplus.blogspot.in/2012/01/uppercase-to-lowercase.html

Bubble sort in C++

noreply@blogger.com (Fatal1ty) — Fri, 17 Feb 2012 07:42:00 +0000

Sorting is used in many programming applications and as there are various sorting algorithms, each
having their respective pros and cons. Bubble sort, is one such search algorithm that is very easy to implement.
Bubble sort can be used to sort both in ascending order as well as in descending order. The basic idea of bubble sort
is to compare two adjoining value and exchange them if they are not in proper order. In every pass, the heaviest element
settles as its appropriate position in the bottom(if is to be sorted in ascending order) and the opposite is true for
sorting in descending order. Bubble sort is useful when a small no. of element are to be sorted as it is a simple algorithm.
However, due to comparatively large no of passes(loop counts), as compared to other sorting algorithms, its is advisable
to use other searching algorithms , e.g quick sort.
A program is given below that sorts an integer array in ascending order using bubble sort algorithm

// Program to implement bubble sort in C++\
#include <iostream>

int main()
{
     int arr[20];
     int size, temp,i,j;
     std::cout<<" Enter the no. of elements you want in the array (max 20 ) : ";
     std::cin>>size;
     std::cout<<" \n Now enter the elements in the array ";
     // loop to insert elements in the array, which is initially empty
     for (i=0; i<size; i++)
     {
          std::cout<<" \n Element "<<i<<" : ";
          std::cin>>arr[i];
     } // end of for loop

     // to sort using bubble sort algorithm(ascending order)

     for (i=0; i<size; i++)
     {
          for (j=0; j<=i; j++)
          {
               if( arr[j] > arr[i]) // exchanges heavy elements with lighter ones
               {
                    temp = arr[j];
                    arr[j] = arr[i];
                    arr[i] = temp;
               }

          } // end of sub loop
     } // end of main loop

     std::cout<<" \n The sorted array is as follows : \n";
     for (i=0; i<size; i++)
     {
          std::cout<<" \n Element "<<i<<" : "<<arr[i];
     } // end of main loop
     return 0;
} // end of main

------ OUTPUT ------

Insertion Sort in C++ : http://programsplusplus.blogspot.in/2012/02/insertion-sort-in-c.html
Selection Sort in C++ : http://programsplusplus.blogspot.in/2012/02/selection-sort-in-c.html

Basic password encryption program

noreply@blogger.com (Fatal1ty) — Sat, 11 Feb 2012 13:20:00 +0000

Password encryption is basically converting a password in some other format(instead of text) into a format
that is not recognizable,so that i becomes secure. This is essential when we want to write down passwords without
the fear of having to risk the likelihood of revealing our password. Also since encrypted passwords contain special characters
such as %,$ , it becomes very difficult for brute force attacks to crack it. There are many password encrypters available, that use
sophisticated techniques to encrypt passwords. One simple method is by converting a series of characters into their respective ASCII
values. The program given below encrypts the password as follows :

Step1 : The user enters a password to encrypt
Step2 : The password is checked to see whether it is UPPERCASE OR LOWERCASE
Step3 : If it is lowercase then it is converted into uppercase and vice-verse
Step4 : Then the converted string is converted into ASCII. Vola, the password is encrypted and contains only numeric values

Even though this encryption method is very simple, it is effective especially against a person who little knowledge of ASCII values.

// BASIC PASSWORD ENCRYPTER
// USES ASCII CODES FOR ENCRYPTION
// VERSION 1.0
// CREATED BY : DEEPAK SHARMA

#include <iostream>
#include <cctype>

int main()
{
     char password[20];
     char temp[20];
     int encrypt_password[20];
     int i,length;
     std::cout<<" Enter the password to encrypt (max 20 characters ) : ";
     std::cin.getline(password,sizeof(password));
      // to check whether the password is in UPPERCASE or LOWERCASE
     for (i=0; password[i] != '\0'; i++ )
     {
           if ( islower(password[i]) )
                    temp[i] = toupper(password[i]);
           else if ( isupper(password[i]) )
                    temp[i] = tolower(password[i]);
          else
                    temp[i] = password[i];
      } //end of loop
             temp[i] = '\0';

     // to convert the characters to their respective ASCII values
      for ( i=0; temp[i] != '\0'; i++ )
      {
               encrypt_password[i] = temp[i];
      }
        length = i;
      // to display the encrypted password

      std::cout<<"\n ENTERED PASSWORD : "<<password;

      std::cout<<" \n\n ENCRYPTED PASSWORD : ";
      for (i=0; i<length; i++)
      {
          std::cout<<encrypt_password[i];
      }

     return 0;
} // end of main


Basic password encrypter version 1.0

---

Multiple increment opeartors in C and use of printf

noreply@blogger.com (Fatal1ty) — Sun, 05 Feb 2012 08:28:00 +0000

This post is in reference to a problem about which I posted earlier, under the title "multiple increment operators". Now while using multiple increment operators in C , the results are completely different, which also encouraged me to explain a little bit about the printf(); used in C for basic output operations.
Consider the following snippet of code :-
// Multiple increment opearators in C

#include <cstdio>
int main()
{
     int x = 5;
     printf("%d%d%d%d%d",x++,x--,++x,--x,x);
     return 0;
}
The program give the output as 45545.
Now when the statement printf("%d%d%d%d%d",x++,x--,++x,--x,x); is executed, all the variables are processed from right to left , and pushed accordingly in the stack. i.e
x - PUSH --> means x = 5;
--x (per-decrement) - PUSH --> means x = 4;
++x (per-increment) - PUSH --> means x = 5;

x-- (post-decrement) - PUSH --> means x = 5 (but afterwards x = 4 due to post decrement)
x++(post-increment) - PUSH --> means x = 4; (but afterwards x = 5 due to post increment).

Now the printf() statement , prints the values of x , hence the output is 45545(remember stacks follow LIFO,last in first out).
------ OUTPUT ------

For more info on using printf(), follow this link : http://stackoverflow.com/questions/2198880/how-does-printf-work

------ Related Posts ------
Multiple increment operators in c++ : http://programsplusplus.blogspot.in/2012/01/multiple-increment-operators-in-sinlge.html

Deletion in an integer array

noreply@blogger.com (Fatal1ty) — Sun, 05 Feb 2012 06:43:00 +0000

Deletion inside data structures is very common, especially inside arrays as they have static(fixed) memory allocation. To delete an element from the array simply move each element one step above. For example, if the array was initially as follows :

Element 0 : 23
Element 1 : 98
Element 2 : 87
Element 3 : 12
and suppose we want to delete an element at the 1st position(i.e.98), then we simply shift each element one position above. So, the new array after deleting value 98 from the 1st position would be as follows :
Element 0 : 23
Element 1 : 87
Element 2 : 12
Hence we have successfully deleted an element from the array. The process is contrary to the method that we have used to perform insertion operation in the array(see the previous post). Read the given code below, for a better understanding :

// Program to delete element in an array (for GCC compiler package and similar compilers)

#include <iostream>
// function to delete an element from the array
int deletion_array(int array[],int s,int pos)
{
     for (int i=pos; i<=s; i++)
     {
          array[i] = array[i+1]; //shifts each element one position above
     }
     s--;    // decrements the size, as one element is deleted
     return s; // returns the new size of the new array
}

int main()
{
     int size,value,position;
     int arr[21];
      // prompts the used to enter the maximum no. of elements in the array
     std::cout<<" Enter the no of elements you want in the array (max 20) : ";
     std::cin>>size;
      // to insert the elements in the array
     for (int i=0; i<size; i++)
     {
          std::cout<<" \n Element "<<i<<" : ";
          std::cin>>arr[i];
     }
     std::cout<<"\n Enter the position where you want to delete the value : ";
     std::cin>>position;
     size = deletion_array(arr,size,position);
      // calls the function to delete the specified element
     std::cout<<" \n Deletion successfull !!! , the new array is as follows ";

     // displays the new array
     for (int i=0; i<size; i++)
     {
          std::cout<<"\n Element "<<i<<" : "<<arr[i];
     }
     return 0;
} // end of main
Note : If the console window shuts down immedeaitly, then add std::cin.get(); before return 0; to fix the problem. :)

------ OUTPUT ------

------ Related Posts ------
Insertion in array : http://programsplusplus.blogspot.in/2012/02/insertion-in-integer-array.html