ctype_alnum

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

ctype_alnum做字母和数字字符检测

说明

ctype_alnum ( string $text ) : bool

检查提供的string,text 是否全部为字母和(或)数字字符。

参数

text

测试字符串。

返回值

如果text中所有的字符全部是字母和(或者)数字,返回 true 否则返回false

范例

Example #1 A ctype_alnum() 示例 (使用默认的区域设置)

<?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";
    }
}
?>

以上例程会输出:

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

注释

Note:

如果给出一个 -128 到 255 之间(含)的int, 将会被解释为该值对应的ASCII字符 (负值将加上 256 以支持扩展ASCII字符). 其它整数将会被解释为该值对应的十进制字符串.

参见

User Contributed Notes

marcelocamargo at linuxmail dot org 04-Jan-2016 04:42
It is also important to note that the behavior of `ctype_alnum` differs according to the operating system. For UNIX-based operating system, if you pass a value that is not a string (or an overloaded object), independently of the value, it will always result in false. However, if we do the same on Windows, using, for example, -1 as literal (a minus and a number greater than 0), we'll have true as result.

<?php var_dump(ctype_alnum(-1));
// UNIX: bool(false)
// Windows: bool(true)
Anonymous 28-Jan-2013 05:12
Quicktip: If ctype is not enabled by default on your server, replace ctype_alnum($var) with preg_match('/^[a-zA-Z0-9]+$/', $var).
Rory 07-Dec-2009 04:42
Just for the record, Gentoo doesn't include this function by default. You'll have to recompile PHP with the "ctype" USE flag.
thinice at gmail dot com 22-Jul-2009 02:46
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.';
}
?>