If

if (condition) { first statements to be executed ;
second statements to be executed ; }


Above is the syntax of the if statement. The statements to be executed are enclosed within curly brackets.

Example
---------

Write a function called message( ) that accepts an integer as an argument. The message ( ) function should print one of the following, depending on the value of its argument.

Argument Value                     Message

0                                     File not found

1                                     File full

2                                     File not found

3                                     Not enough memory

4                                     Illegal data

The following C   program will be the solution

int i;
main ( ) ;
{
scanf ( " %d", &i);
message ( );
}

message( )
{
if ( i = = 0) printf ( " file not opened " );
else
if ( i = = 1) printf ( " file full " );
else
if ( i = = 2) printf ( " file not found " );
else
if ( i = = 3) printf ( " not enough memory " );
else
if ( i = = 4) printf ( " illegal data " );
}

Now when this program is compiled and run

if you input 0, output is file not opened

if you input 1, output is file full

if you input 2, output is file not found

if you input 3, output is not enough memory

if you input 4, output is illegal data