PHP-正则表达式仅允许使用字母和数字 [英] PHP - regex to allow letters and numbers only

问题描述

我尝试过:

preg_match("/^[a-zA-Z0-9]", $value)

但是我猜我做错了.

推荐答案

1.使用PHP内置的 ctype_alnum

您无需为此使用正则表达式，PHP具有内置函数ctype_alnum，它将为您执行此操作，并且执行速度更快:

1. Use PHP's inbuilt ctype_alnum

You dont need to use a regex for this, PHP has an inbuilt function ctype_alnum which will do this for you, and execute faster:

<?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";
    }
}
?>

2.或者，使用正则表达式

如果您非常想使用正则表达式，则有几种选择.

2. Alternatively, use a regex

If you desperately want to use a regex, you have a few options.

首先:

preg_match('/^[\w]+$/', $string);

\w包含多个字母数字(包括下划线)，但包含所有 \d.

\w includes more than alphanumeric (it includes underscore), but includes all of \d.

或者:

/^[a-zA-Z\d]+$/

甚至只是:

/^[^\W_]+$/

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