Question

我有一个正则表达式，用于检查长度为4到25个字符的用户名，后跟任何可选的空格键和/或单个逗号。您可能已经猜到，通过键入“Username1，Username2，Username3”等内容，可以将其用于向多人发送个人消息。

$rule = "%^\w{4,25}( +)?,?( +)?$%";
preg_match_all($rule, $sendto, $out);
foreach($out[1] as $match) {
    echo $match;
}

正则表达式似乎正在完成它的工作，虽然当我使用preg_match_all（）并尝试对所有值进行排序时，它不会向浏览器回显任何内容。我怀疑我对preg_match_all有些误解，因为我的正则表达式似乎正在起作用。

Answer 1

您的正则表达式缺少用户名上的捕获组([\w]{4,25})，请尝试以下操作：

<?
$users = "Username1, Username2      , Username3       ";
preg_match_all('/([\w]{4,25})(?:\s+)?,?/', $users, $result, PREG_PATTERN_ORDER);
foreach($result[1] as $user) {
    echo $user;
}
/*
Username1
Username2
Username3
*/

Live Demo

正则表达式解释：

([\w]{4,25})(?:\s+)?,?

Match the regex below and capture its match into backreference number 1 «([\w]{4,25})»
   Match a single character that is a “word character” (Unicode; any letter or ideograph, any number, underscore) «[\w]{4,25}»
      Between 4 and 25 times, as many times as possible, giving back as needed (greedy) «{4,25}»
Match the regular expression below «(?:\s+)?»
   Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
   Match a single character that is a “whitespace character” (any Unicode separator, tab, line feed, carriage return, vertical tab, form feed, next line) «\s+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Match the character “,” literally «,?»
   Between zero and one times, as many times as possible, giving back as needed (greedy) «?»

PHP preg_match_all不返回值

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