Looping Statements in C .

     Looping

In computer programming, a loop is a sequence of commands or statements that are repeated many times.

Looping statements in C language

C language provides the following looping statements:

• for statement
• while statement
• do…while statement

Let us learn C programming Looping concept by executing following programs.

            Sample Program based on Looping concept

C program to print 1 to 10 numbers using for loop.

#include<stdio.h>

int main()

{

  int i;

  for(i=1; i<=10; i++)

  {

     printf("%d ", i);

  }

  return 0;

}

Output of program

1 2 3 4 5 6 7 8 9 10

C programs based on for loop

1.C program to print 1 to 10 numbers using for loop.

#include<stdio.h>

int main()
{
  int i;
  for(i=1; i<=10; i++)
  {
printf("%d ", i);
  }
  return 0;
}


Output of the program

1 2 3 4 5 6 7 8 9 10

2.C program to print 10 to 1 numbers using for loop.

#include<stdio.h>
int main()
{
int i;
for(i=10; i>0; i--)
{
printf("%d ", i);
}
  return 0;
}

Output of the program:
10 9 8 7 6 5 4 3 2 1

3.C program to find the sum of first 100 natural numbers.

#include<stdio.h>
int main()
{
int i, sum, temp;

sum=0; 
temp=1;

for( i=0; i<100; i++ )
{
sum = sum + temp;
temp = temp + 1;
}

printf("%d",sum);
 return 0;
}


Output of the program:
5050

4.C program to check whether entered number is odd or even.

#include<stdio.h>
void main()
{
int number;

printf("Enter number:");
scanf("%d",&number);

if(number%2 == 0)
printf("Entered number is even.");
else
printf("Entered number is odd.");
}

Output

Enter number:10
Entered number is even.

5.Fibonacci Series in C language.

/* Fibonacci Series in C language.

About Fibonacci series: Each new number in a series is addition of its previous two numbers.

Example of Fibonacci series:0, 1, 1, 2, 3, 5, 8, 13,

*/

#include<stdio.h>

#include<stdlib.h>

int main()

{

     int i, n, n1, n2, n3;

    

     printf("Enter your number:");

     scanf("%d",&n);

    

     if(n<2)

     {

           printf("Please enter number > 2. \n");

           exit(0);

     }

     n1=0; 
     n2=1;

     printf("First %d numbers of Fibonacci series:\n",n);

     printf("%d, %d, ", n1, n2);

     n3 = n1 + n2;

  

     for(i=0; i<n-2; i++)

     {

           printf("%d, ", n3);

           n1=n2;

           n2=n3;

           n3=n1+n2; 

     }
     return 0;

}

Output of the Program:

Enter your number:5

First 5 numbers of Fibonacci series:

0, 1, 1, 2, 3,

6.Swastik Pattern

#include<stdio.h>

int main()

{

     int i,j,n;

     printf("Enter Swastik Size(n):");

     scanf("%d",&n);

     printf("* ");

    

     for(i=0; i<n-2; i++)

           printf("  ");

    

     for(i=0; i<n; i++)  

           printf("* ");

    

     printf("\n");

    

     for(j=0; j<n-2; j++)

     {

           printf("* ");

           for(i=0; i<n-2; i++)

                printf("  ");

           printf("* \n");

     }

    

     for(i=0; i<n*2-1; i++)    

           printf("* ");

     printf("\n");

    

     for(j=0; j<n-2; j++)

     {

           for(i=0; i<=n-2; i++)

                printf("  ");

           printf("* ");

           for(i=0; i<n-2; i++)

                printf("  ");

           printf("* \n");

     }

     for(i=0; i<n; i++)  

           printf("* ");

     for(i=0; i<n-2; i++)

           printf("  ");

     printf("* ");  

     return 0;
}

Output of the Program:

Enter Swastik Size(n):5

*       * * * * *

*       *

*       *

*       *

* * * * * * * * *

        *       *

        *       *

        *       *

* * * * *       *

7.C Program to print A to Z using for loop.

#include<stdio.h>

int main()

{

 int i;

 for(i=65; i<=90; i++)

 {

  printf("%c ",i);

 }

 return 0;

}

Output of the program:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

8.C program to print Z to A using for loop

Program Code 1:

#include<stdio.h>

int main()

{

  int i;

  for(i='Z'; i>='A'; i--)

    printf("%c", i);

  

  return 0;

}

Output of the program:

ZYXWVUTSRQPONMLKJIHGFEDCBA

Same program can also be generated using following code.

Program Code 2:

#include<stdio.h>

int main()

{

    int i;

    //90 is ASCII value of Z

    for(i=90; i>=65; i--)

        printf("%c", i);

    

    return 0;

}

Output of the program:

ZYXWVUTSRQPONMLKJIHGFEDCBA

9.Sum of series 1 + 1/2 + 1/3 + 1/4 + ....N

C PROGRAM TO PRINT SUM OF SERIES 1 + 1/2 + 1/3 + 1/4 + ....N FOR THE GIVEN VALUE OF N.

For example, if N=5, output will be sum of 1 + 1/2 + 1/3 + 1/4 + 1/5, i.e. 2.28 

#include<stdio.h>
int main()
{
  int i, N;
  float sum=0;
  printf("Enter N:");
  scanf("%d", &N);
  if(N<1){
  printf("Enter value of N > 0.");
  exit(1);
  }
  for(i=1; i<=N; i++)
  {
   if(i==1)
   {
   sum=1;
   printf("Series = 1");
   }
   else
   {
     sum = sum + (float)1/i;
     printf(" + 1/%d", i);
   }
  }
  printf("\nSum of the series = %0.2f", sum);
  return 0; 
}

Output of program

Enter N:5
Series = 1 + 1/2 + 1/3 + 1/4 + 1/5
Sum of the series = 2.28