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ctype_alnum

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

ctype_alnum检测字母数字式字符

说明

ctype_alnum(mixed $text): bool

检测提供的 string 类型的 text 是否全部为字母数字。

参数

text

要测试的字符串。

注意:

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.

警告

自 PHP 8.1.0 起,弃用传递非字符串参数。未来该参数将解释为字符串而不是 ASCII 码点。根据预期行为,应将参数转为字符串或显式调用 chr()

返回值

如果 text 中所有的字符不是字母就是数字,则返回 true,否则返回 false。当使用空字符串调用时,结果始终为 false

示例

示例 #1 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";
}
}
?>

以上示例会输出:

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

参见

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User Contributed Notes 4 notes

up
96
thinice at gmail dot com
14 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.';
}
?>
up
11
marcelocamargo at linuxmail dot org
8 years ago
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)
up
20
Anonymous
11 years ago
Quicktip: If ctype is not enabled by default on your server, replace ctype_alnum($var) with preg_match('/^[a-zA-Z0-9]+$/', $var).
up
-12
Rory
14 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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