C Program for Macros with arguments

/* Macros with arguments */
/* Program to test whether entered character is digit */
#define ISDIGIT(y) ( y >= 48 && y <= 57 )
main( )
{
char  ch ;
printf ( "Enter any digit " ) ;
scanf ( "%c", &ch ) ;
if ( ISDIGIT ( ch ) )
printf ( "\nYou entered a digit" ) ;
else
printf ( "\nIllegal input" ) ;
}