Iterative / Loop

Loop control statements in C are used to perform looping operations until the given condition is true. Control comes out of the loop statements once condition becomes false.

TYPES OF LOOP CONTROL STATEMENTS IN C:

There are 3 types of loop control statements in C language. They are,

1. for
2. while
3. do-while

Syntax for each C loop control statements are given in below table with description.

Loop Name	Syntax
for	for (exp1; exp2; expr3) { statements; } Where, exp1 – variable initialization ( Example: i=0, j=2, k=3 ) exp2 – condition checking ( Example: i>5, j<3, k=3 ) exp3 – increment/decrement ( Example: ++i, j–, ++k )
while	while (condition) { statements; } where,  condition might be a>5, i<10
do while	do { statements; } while (condition); where, condition might be a>5, i<10

EXAMPLE PROGRAM (FOR LOOP) IN C:

In for loop control statement, loop is executed until condition becomes false.

C

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

OUTPUT:

0 1 2 3 4 5 6 7 8 9

EXAMPLE PROGRAM (WHILE LOOP) IN C:

In while loop control statement, loop is executed until condition becomes false.

C

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#include <stdio.h>   int main() {   int i=3;     while(i<10)   {      printf("%d\n",i);      i++;   }       }

OUTPUT:

3 4 5 6 7 8 9

EXAMPLE PROGRAM (DO WHILE LOOP) IN C:

In do..while loop control statement, while loop is executed irrespective of the condition for first time. Then 2nd time onwards, loop is executed until condition becomes false.

C

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#include <stdio.h>   int main() {   int i=1;     do   {         printf("Value of i is %d\n",i);       i++;   }while(i<=4 && i>=2);       }

OUTPUT:

Value of i is 1 Value of i is 2 Value of i is 3 Value of i is 4

DIFFERENCE BETWEEN WHILE & DO WHILE LOOPS IN C LANGUAGE:

while	do while
Loop is executed only when condition is true.	Loop is executed for first time irrespective of the condition. After executing while loop for first time, then condition is checked.

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