While loop in C language

While loop is also known as a pre-tested loop. It repeatedly executes a target statement as long as a given condition is true. It can be viewed as a repeating if statement.

The while loop is mostly used in the case where the number of iterations is not known in advance.

Syntax

while(condition) {
   statement(s);
}

• The condition may be any expression, and true is any nonzero value.
• The loop iterates while the condition is true.
• When the condition becomes false, the program control passes to the line immediately following the loop.

How while loop works?

1. The while loop evaluates the Condition inside the parentheses ().
2. If Condition is true, statements inside the body of while loop are executed. Then, Condition is evaluated again.
3. The process goes on until Condition is evaluated to false.
4. If Condition is false, the loop terminates (ends).

Flowchart of while loop in C

// Print numbers from 1 to 5

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

  return 0;
}