---
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: `else` and `else if` sections are not required, while `if` is mandatory. Furthermore, `else` and `else if` can only be used following an `if` statement. In the instance when one `if` statement is executed, the following `else if` and `else` statements are ignored.

## 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
```
## Nested IF Statement
```
if( boolean_expression 1) {

   /* Executes when the boolean expression 1 is true */
   if(boolean_expression 2) {
      /* Executes when the boolean expression 2 is true */
   }
}
```
### Example
```
#include <stdio.h>
 
int main () {

   /* local variable definition */
   int a = 100;
   int b = 200;
 
   /* check the boolean condition */
   if( a == 100 ) {
   
      /* if condition is true then check the following */
      if( b == 200 ) {
         /* if condition is true then print the following */
         printf("Value of a is 100 and b is 200\n" );
      }
   }
   
   printf("Exact value of a is : %d\n", a );
   printf("Exact value of b is : %d\n", b );
 
   return 0;
}
```
for more info visit <https://www.tutorialspoint.com/cprogramming/nested_if_statements_in_c.htm>