What is while an example of?

A loop is used for executing a block of statements repeatedly until a given condition returns false. In the previous tutorial we learned for loop. In this guide we will learn while

What is while an example of?

A loop is used for executing a block of statements repeatedly until a given condition returns false. In the previous tutorial we learned for loop. In this guide we will learn while loop in C.

C  while loop

Syntax of while loop:while (condition test) { //Statements to be executed repeatedly // Increment (++) or Decrement (--) Operation }

Flow Diagram of while loop

C while loop

Example of while loop#include <stdio.h> int main() { int count=1; while (count <= 4) { printf("%d ", count); count++; } return 0; }

Output:1 2 3 4

step1: The variable count is initialized with value 1 and then it has been tested for the condition.
step2: If the condition returns true then the statements inside the body of while loop are executed else control comes out of the loop.
step3: The value of count is incremented using ++ operator then it has been tested again for the loop condition.

Guess the output of this while loop#include <stdio.h> int main() { int var=1; while (var <=2) { printf("%d ", var); } }

The program is an example of infinite while loop. Since the value of the variable var is same (there is no ++ or  operator used on this variable, inside the body of loop) the condition var<=2 will be true forever and the loop would never terminate.

Examples of infinite while loop

Example 1:#include <stdio.h> int main() { int var = 6; while (var >=5) { printf("%d", var); var++; } return 0; }

Infinite loop: var will always have value >=5 so the loop would never end.

Example 2:#include <stdio.h> int main() { int var =5; while (var <=10) { printf("%d", var); var--; } return 0; }

Infinite loop: var value will keep decreasing because of - operator, hence it will always be <= 10.

Use of Logical operators in while loop

Just like relational operators (<, >, >=, <=, ! =, ==), we can also use logical operators in while loop. The following scenarios are valid :while(num1<=10 && num2<=10)

-using AND(&&) operator, which means both the conditions should be true.while(num1<=10||num2<=10)

OR(||) operator, this loop will run until both conditions return false.while(num1!=num2 &&num1 <=num2)

Here we are using two logical operators NOT (!) and AND(&&).while(num1!=10 ||num2>=num1)

Example of while loop using logical operator

In this example we are testing multiple conditions using logical operator inside while loop.#include <stdio.h> int main() { int i=1, j=1; while (i <= 4 || j <= 3) { printf("%d %d\n",i, j); i++; j++; } return 0; }

Output:1 1 2 2 3 3 4 4 PreviousNext

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