The ctype_alnum() function in PHP check for alphanumeric character(s). It returns TRUE if every character in string str is either a letter or a digit, FALSE otherwise.
Syntax
ctype_alnum(str)
Parameters
str − The tested string
Return
The ctype_alnum() function returns TRUE if every character in str is either a letter or a digit, FALSE otherwise.
Example
The following is an example −
<?php
$str = array('demo', 'test#$!test');
foreach ($str as $a) {
if (ctype_alnum($a)) {
echo "$a consists of all letters or digits. \n";
} else {
echo "$a does not have all letters or digits. \n";
}
}
?>Output
demo consists of all letters or digits. test#$!test does not have all letters or digits.