isalnum

tests a character to see if it is alphanumeric

Synopsis:

#include <ctype.h>
int isalnum( int c );

Description:

The isalnum() function tests if the argument c is an alphanumeric character ('a' to 'z', 'A' to 'Z', or '0' to '9'). An alphanumeric character is any character for which isalpha() or isdigit() is true.

Returns:

The isalnum() returns zero if the argument is neither an alphabetic character nor a digit. Otherwise, a non-zero value is returned.

The result is only valid for char arguments and EOF. The result is undefined for other types of arguments.

See also:

isalpha(), isdigit(), islower()

Examples:

#include <stdio.h>
#include <ctype.h>

void main()
  {
    if( isalnum( getchar() ) ) {
      printf( "is alpha-numeric\n" );
    }
  }

Classification:

ANSI

Systems:

All (except DOS/PM)