It is perfectly all right if we write an entire if-else construct within either the body of the if statement or the body of an else statement. This is called ‘nesting’of ifs. This is shown in the following program.

#include<stdio.h>
int main( )
{
int i ;
printf ( "Enter either 1 or 2 " ) ;
scanf ( "%d", &i ) ;
if ( i == 1 )
printf ( "i equals to 1" ) ;
else
{
    if ( i == 2 )
    printf ( "i equals 2" ) ;
    else
    printf ( "i is nor 1 neither 2" ) ;
}
    getchar();
return 0;
}