PHP | ctype_alnum() (Check for Alphanumeric)

A ctype_alnum() function in PHP used to check all characters of given string/text are alphanumeric or not. If all characters are alphanumeric then return TRUE, otherwise return FALSE. Syntax:

 bool ctype_alnum ($text)

Parameters Used:

• $text : It is a mandatory parameter which specifies the string.

Examples:

Input  : Geeks
Output : Yes
Explanation : String "Geeks" is alphanumeric.
              Note: Read Standard c local letter.
      
Input  : '%%%Contribute_article on GFG!!!'
Output : No
         
Explanation : String contains Special characters.
                 

Note: Except string or digit, if we input anything then it will return FALSE.

Below programs illustrate the ctype_alnum() function. Program :1 Drive a code ctype_alnum()() function for better understand. 

PHP

<?php

// PHP program to check given string is
// all characters are alphanumeric

$string = 'GeeksforGeeks';

    if ( ctype_alnum($string))
        echo "Yes\n";
    else
        echo "No\n";

?>

Output:

Yes

Program: 2 Drive a code of ctype_alnum() function where input will be an array of string integers, string with special symbols. 

PHP

<?php
// PHP program to check given string is
// all characters are alphanumeric

$strings = array(
    'Geeks',
    'geek@gmail.com',
    '2018',
    'GFG2018',
    'a b c ',
    '@!$%^&*()|2018'
);

// Checking above given four strings
// by used of  ctype_alnum() function .
foreach ($strings as $test) {

    if (ctype_alnum($test))
        echo "Yes\n";
    else
        echo "No\n";

}

?>

Output:

Yes
No
Yes
Yes
No
No

References :http://php.net/manual/en/function.ctype-alnum.php