freeCodeCamp/guide/english/c/if/index.md

title
If

If

The if statement executes different blocks of code based on conditions.

if (condition) {
	// Do something when `condition` is true
}
else {
	// Do something when original if `condition` is false
}

When condition is true, code inside the if section executes, otherwise else executes. Sometimes you would need to add a second condition. For readability, you should use a else if rather than nesting if statements.

if (condition) {
	// Do something if `condition` is true
}
else if (anotherCondition) {
	// Do something if `anotherCondition` is true
}
else {
	// Do something if `condition` AND `anotherCondition` is false
}

Note that the else and else if sections are not required, while if is mandatory.

Example

#include <stdio.h>

int main () {

   // Local variable definition
   int a = 100;

   // Check the boolean condition
   if(a < 5) {
      // If condition is true then print the following
      printf("a is less than 5!\n" );
   }
   else {
      // If condition is false then print the following
      printf("a is not less than 5!\n" );
   }

   printf("Value of a is : %d\n", a);

   return 0;
}

Output

-> a is not less than 5!
-> Value of a is : 10