isalnum function(Test for Alphanumeric) in C Language – example and detail

In the C Programming Language, the isalnum feature exams whether c is alphanumeric.

Syntax

The syntax for the isalnum function in the C Language is:

int isalnum(int c);

Parameters or Arguments

c

The value to test whether it is alphanumeric.

Note c is regarded to be alphanumeric if either isalpha(c) is authentic or isdigit(c) is true.

Returns

The isalnum function returns a nonzero price if c is alphanumeric and returns zero if c is now not alphanumeric.

Required Header

In the C Language, the required header for the isalnum characteristic is:

#include <ctype.h>

Applies To

In the C Language, the isalnum feature can be used in the following versions:

ANSI/ISO 9899-1990

isalnum Example

/* Example using isalnum by TechOnTheNet.com */

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

int main(int argc, const char * argv[])
{
    /* Define a temporary variable */
    unsigned char test;

    /* Assign a test letter to the variable */
    test = 'T';

    /* Test to see if this character is alphanumeric */
    if (isalnum(test) != 0) printf("%c is alphanumeric\n", test);
    else printf("%c is not alphanumeric\n", test);

    /* Assign a non-alphanumeric character to the variable */
    test = '!';

    /* Test to see if this character is alphanumberic */
    if (isalnum(test) != 0) printf("%c is alphanumeric\n", test);
    else printf("%c is not alphanumeric\n", test);

    return 0;
}

When compiled and run, this application will output:

T is alphanumeric
! is not alphanumeric

Similar Functions

Other C features that are comparable to the isalnum function:

isalpha characteristic isdigit characteristic

See Also

Other C functions that are noteworthy when dealing with the isalnum function:

islower characteristic isupper feature