# Syntax

An if statement can be followed by an optional else statement, which executes when the boolean expression is false.

The syntax of an if...else statement in C programming language is:

if(boolean_expression)
{
/* statement(s) will execute if the boolean expression is true */
}
else
{
/* statement(s) will execute if the boolean expression is false */
}

If the boolean expression evaluates to true, then the if block of code will be executed, otherwise else block of code will be executed.

C programming language assumes any non-zero and non-null values as true, and if it is either zero ornull, then it is assumed as false value.

# Example

#include <stdio.h>

int main ()
{
/* local variable definition */
int a = 100;

/* check the boolean condition */
if( a < 20 )
{
/* if condition is true then print the following */
printf("a is less than 20\n" );
}
else
{
/* if condition is false then print the following */
printf("a is not less than 20\n" );
}
printf("value of a is : %d\n", a);

return 0;
}

When the above code is compiled and executed, it produces the following result:

a is not less than 20;
value of a is : 100