Syntax:

    #include <cctype>
    int isdigit( int ch );

The function isdigit() returns non-zero if its argument is a digit between 0 and 9. Otherwise, zero is returned.

     char c;
     scanf( "%c", &c );
     if( isdigit(c) )
       printf( "You entered the digit %c\n", c );

Related Topics: isalnum, isalpha, iscntrl, isgraph, isprint, ispunct, isspace, isxdigit