ISDIGIT FUNCTION

#include <stdio.h>

int main() {

  if( isdigit( '9' ) )
  {
     printf( "Character 9 is a digit\n" );
  }
  if( isdigit( 'A' ) )
  {
     printf( "Character A is digit\n" );
  }
  
  getchar();
  return 0;
}