The do-while loop in C runs the code inside the loop once, and then checks the condition. If the condition is true, it repeats the loop; if the condition is false, the loop stops.
Syntax:
do {
// Code to be executed
} while (condition);
Explanation:
- do: Starts the loop and indicates that the code block inside the loop should execute.
- Block of code: The code inside the curly braces { } will execute at least once before checking the condition.
- while (condition): After executing the block of code, the condition is evaluated. If the condition is true, the loop will repeat; otherwise, it will terminate.
Example:
#include <stdio.h>
int main() {
int count = 1;
// do-while loop
do
{
printf("number:%d\n", count);
count++; // Increment the counter
}
while (count <= 5);
return 0;
}
Output:
number:2
number:3
number:4
number:5
Example: If we define count > 5 in the while loop then it will execute only one time.
#include <stdio.h>
int main() {
int count = 1;
// do-while loop
do
{
printf("number:%d\n", count);
count++; // Increment the counter
}
while (count > 5);
return 0;
}
Output:
C Do While loop – Questions and Answers
Q 1: What is a do-while loop in C?
Ans: A loop that executes at least once before checking the condition.
Q 2: Is do-while an exit-controlled loop?
Ans: Yes, the condition is checked after execution.
Q 3: What is the key difference between while and do-while?
Ans: do-while runs at least once; while may not.
Q 4: Is semicolon required after do-while?
Ans: Yes, a semicolon is mandatory.
Q 5: Where is do-while commonly used?
Ans: In menu-driven programs.
C do while loop – Objective Questions (MCQs)
Q1. What is the correct syntax of a while loop in C?
Q2. In a do-while loop, the condition is checked:
Q3. What is the output of this code?
int i = 1;
do {
printf("%d ", i);
i++;
} while (i <= 3);
Q4. Which statement about the do-while loop is true?
Q5. What is the output of this code?
int i = 5;
do {
printf("Hello ");
i++;
} while (i < 5);