C Loop control statements [1.0.11]

      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.

S.no	Loop Name	Syntax	Description
1	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 )
2	while	while (condition) { statements; }	where,  condition might be a>5, i<10
3	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.

#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.

#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 2^nd time onwards, loop is executed until condition becomes false.

#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:

S.no	while	do while
1	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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