Do While Loop in C

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A do-while loop is similar to a while loop. A do-while loop is used when we want to execute the loop at least once.

• A do-while loop's body executes first and condition checked latter.
• If the condition is true then the loop body executed again.
• If the condition is false then the loop stops its execution.
• A do-while loop is guaranteed to execute at least one time.

Syntax of do while loop

do { // loop scope } while(condition);

• You can the condition appears at the end of the loop, so the statements in the loop scope execute once before the condition is tested.
• If the condition is true then the flow of control jumps back up to do and the statements in the loop execute again.
• The above process repeats until the condition is false.

Example 1

#include<stdio.h> int main() { int i=1; do { printf("%d\n", i); i = i + 1; } while(i<5); printf("Process Complete"); return 0; }

Output

1 2 3 4 Process Complete

Problem 1

Can you find the output of the below program:

#include<stdio.h> int main() { int sum=0; int i=1; do { sum = sum + i; i = i + 2; } while(sum<40 || i<10); printf("%d, %d", sum, i); return 0; }

Example 2

Notice the condition and output of the below program very carefully, you can see the condition is false but still loop scope runs one time.

#include<stdio.h> int main() { int a=10; do { printf("Hello World"); } while(a<5); return 0; }

Output

Hello World

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