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.';
}
?>
PHP - Manual: ctype_alnum
2024-11-15
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
示例 #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
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.
add a note
User Contributed Notes 4 notes
thinice at gmail dot com ¶
12 years ago
marcelocamargo at linuxmail dot org ¶
6 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)
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