PHP 5.6.0beta1 released

ctype_alnum

(PHP 4 >= 4.0.4, PHP 5)

ctype_alnumCheck for alphanumeric character(s)

Description

bool ctype_alnum ( string $text )

Checks if all of the characters in the provided string, text, are alphanumeric. In the standard C locale letters are just [A-Za-z].

Parameters

text

The tested string.

Return Values

Returns TRUE if every character in text is either a letter or a digit, FALSE otherwise.

Examples

Example #1 A ctype_alnum() example (using the default locale)

<?php
$strings 
= array('AbCd1zyZ9''foo!#$bar');
foreach (
$strings as $testcase) {
    if (
ctype_alnum($testcase)) {
        echo 
"The string $testcase consists of all letters or digits.\n";
    } else {
        echo 
"The string $testcase does not consist of all letters or digits.\n";
    }
}
?>

The above example will output:

The string AbCd1zyZ9 consists of all letters or digits.
The string foo!#$bar does not consist of all letters or digits.

See Also

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User Contributed Notes 3 notes

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18
thinice at gmail dot com
4 years ago
ctype_alnum() is a godsend for quick and easy username/data filtering when used in conjunction with str_replace().

Let's say your usernames have dash(-) and underscore(_) allowable and alphanumeric digits as well.

Instead of a regex you can trade a bit of performance for simplicity:

<?php
$sUser
= 'my_username01';
$aValid = array('-', '_');

if(!
ctype_alnum(str_replace($aValid, '', $sUser))) {
    echo
'Your username is not properly formatted.';
}
?>
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3
Rory
4 years ago
Just for the record, Gentoo doesn't include this function by default. You'll have to recompile PHP with the "ctype" USE flag.
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3
Anonymous
1 year ago
Quicktip: If ctype is not enabled by default on your server, replace ctype_alnum($var) with preg_match('/^[a-zA-Z0-9]+$/', $var).
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