ctype_alnum()

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

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

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)的整数,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

• ctype_alpha()做纯字符检测
• ctype_digit()做纯数字检测
• setlocale()设置地区信息

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.';
}
?>

Quicktip: If ctype is not enabled by default on your server, replace ctype_alnum($var) with preg_match('/^[a-zA-Z0-9]+$/', $var).

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)

Just for the record, Gentoo doesn't include this function by default. You'll have to recompile PHP with the "ctype" USE flag.