正则表达式模式 - 匹配以 @ 开头的单词 [英] Regex pattern - match word that starts with @

问题描述

我的移动应用程序就像移动平台(WP7、Silverlight、.NET)上的论坛.一项功能是通过写入@"字符后跟用户名来标记其他用户.

在服务器端，PHP，我正在解析文本，使其与标签匹配并用更易读的字符串替换它们，例如 [tag](display name)|(user id)[/tag][tag](display name)|(user id)[/tag]，但这对我们的目的来说并不重要.

为了匹配标签，我用空格替换了所有特殊字符，这样我就可以防止像 .... @name, .... 这样的情况.然后我将删除前一个命令可能已创建的所有多个空格.最后，我将每个空格分开，然后检查该单词是否以@"字符开头.这当然不是最好的方法，但这是我目前设法做到的.有一个弱点，换行符使我的代码失败.例如:

你好，这是我的第一行因为我去第二然后我标记@Jonh谁是好孩子

在这种情况下，我将在下面编写的代码失败.其中 $resp 是要解析的文本.

if (strpos($resp,'@') !== false) {$new_str = preg_replace('/[^a-zA-Z0-9_ \@]/', ' ', $resp);$new_str = preg_replace('/\s+/', ' ', $new_str);foreach(explode(' ', $new_str) as $word){如果 (strpos($word, '@') === 0) {//找到我的标签！}}}}

你建议怎么做?

解决方案

与其使用正则表达式替换您不想匹配的所有内容，您应该能够立即匹配任何前面带有 @ 的单词.

$subject = "..blah.. @name,..blah..@hello,blah";$pattern = '/@\w+/';preg_match_all($pattern, $subject, $matches);print_r($matches);

输出:

Array ( [0] => Array ( [0] => @name [1] => @hello ) )

/@\w+/ 假设只有数字、字母和下划线(这就是 \w 匹配的内容)是有效匹配(即@user123_xd)，如果需要的话例如，在有效匹配(例如@user1a-12)中包含 -(破折号)，则 $pattern 将是 /@[\w-]+/

My mobile application is just like a forum on mobile platform (WP7, Silverlight, .NET). One feature consists in tagging other users by writing "@" char followed by the username.

On server side, PHP, I'm parsing the text so that it matches tags and replace them with more readable string such as [tag](display name)|(user id)[/tag], but that's not important for our purpose.

In order to match tags, I'm replacing all special chars with a space so I can prevent this like .... @name, ..... Then I'm removing all multiple spaces that the previous command could have been created. And finally I'm splitting each whitespace and then I check if that word begins with "@" char. This is not of course the best method, but It's what I managed to do so far. There's a weak point, new line chars make my code fail. For example:

Hello, this is my first line
since I go to second and then I tag
@Jonh
who is a good boy

In case like this, the code I'm going to write below fails. Where $resp is the text to parse.

if (strpos($resp,'@') !== false) {
    $new_str = preg_replace('/[^a-zA-Z0-9_ \@]/', ' ', $resp);
    $new_str = preg_replace('/\s+/', ' ', $new_str);

    foreach(explode(' ', $new_str) as $word)
    {
        if (strpos($word, '@') === 0) {
            //found my tag!                 
            }

        }   
    }
}

What would you advise to do?

解决方案

Rather than using regex to replace everything you don't want to match, you should be able to immediately match any word with an @ before it.

$subject = "..blah.. @name, ..blah..@hello,blah";
$pattern = '/@\w+/';
preg_match_all($pattern, $subject, $matches);
print_r($matches);

Output:

Array ( [0] => Array ( [0] => @name [1] => @hello ) )

/@\w+/ assumes that only numbers, letters and underscores (thats what the \w matches) are valid matches (i.e. @user123_xd), if you want to include for example the - (dash) in valid matches (e.g. @user1a-12) then the $pattern would be /@[\w-]+/

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