isalnum()

test a character to see if it's 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:

A nonzero value if the character is alphabetic (A-Z or a-z) or a digit (0-9), otherwise, zero.

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

Examples:

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

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

Classification:

ANSI

See also:

isalpha(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit()