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.Â
PHP
<?phpÂ
// PHP program to check given string is // all characters are alphanumericÂ
$string = 'neveropen';Â
    if ( ctype_alnum($string))        echo "Yes\n";    else        echo "No\n";Â
?> |
Output:
Yes
Program: 2 Drive a code of ctype_alnum() function where input will be an array of string integers, string with special symbols.Â
PHP
<?php// PHP program to check given string is // all characters are alphanumericÂ
$strings = array(    'Geeks',    'geek@gmail.com',    '2018',    'GFG2018',    'a b c ',    '@!$%^&*()|2018');Â
// 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";     }Â
?> |
Output:
Yes No Yes Yes No No
References :http://php.net/manual/en/function.ctype-alnum.php
