PHP 正则表达式用于在字符第一次出现时分割字符串

发布于 2024-09-13 22:29:15 字数 452 浏览 4 评论 0原文

这可能是一个蹩脚的问题，但我对正则表达式完全是新手。我有一些格式的文本数据：

公司名称：公司名称、地点。
公司地址：一些，地址，这里。
链接： http://www.somelink.com

现在，我想使用正则表达式来分割这些到一个名称：值对的数组中。我正在尝试的正则表达式是 /(.*):(.*)/ 和 preg_match_all() ，它确实适用于前两行，但在第三行上它在一个部分返回“Link: http:”，在另一部分返回“//www.somelink.com”。

那么，有没有办法只在第一次出现字符“:”时分割行？

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君勿笑 2024-09-20 22:29:15

使用否定字符类（参见 rubular.com）：

/^([^:]*):(.*)$/m

[…]< /code> 是一个字符类。像 [aeiou] 之类的东西匹配任何小写元音之一。 [^…] 是一个否定字符类。 [^aeiou] 匹配除小写元音之外的任何内容之一。

模式开头和结尾的 ^ 和 $ 是行锚点。 m 修饰符打开多行模式。

原始模式的问题在于，当您可以更具体时，您正在（ab）使用 . ，并且由于 * 是贪婪的，因此第一组被击败了。人们很容易尝试通过不情愿地重复来“修复”这个问题，但最好是更具体地说明第一组匹配除 : 之外的任何内容。

但请注意，这是一个带有捕获的匹配模式。它实际上并不是仅匹配分隔符的分割模式。分隔符模式实际上只是 :。

PHP 片段

鉴于此：

$text = <<<EOT
Company Name: Name of the company, place.
Company Address: Some, address, here.
Link: http://www.somelink.com
EOT;

preg_match_all('/^([^:]*):(.*)$/m', $text, $matches, PREG_SET_ORDER);

print_r($matches);

输出为 (如 ideone.com 上所示< /a>):

Array
(
    [0] => Array
        (
            [0] => Company Name: Name of the company, place.
            [1] => Company Name
            [2] =>  Name of the company, place.
        )

    [1] => Array
        (
            [0] => Company Address: Some, address, here.
            [1] => Company Address
            [2] =>  Some, address, here.
        )

    [2] => Array
        (
            [0] => Link: http://www.somelink.com
            [1] => Link
            [2] =>  http://www.somelink.com
        )

)

Use negated character class (see on rubular.com):

/^([^:]*):(.*)$/m

The […] is a character class. Something like [aeiou] matches one of any of the lowercase vowels. [^…] is a negated character class. [^aeiou] matches one of anything but the lowercase vowels.

The ^ and $ at the beginning and end of the pattern are the beginning and end of the line anchors. The m modifiers turns on the multi-line mode.

The problem with your original pattern is that you're (ab)using . when you could've been a lot more specific, and since * is greedy, the first group overmatched. It's tempting to try to "fix" that by making the repetition reluctant, but it's MUCH better to be more specific and say that the first group is matching anything but :.

Note however that this is a matching pattern, with captures. It's not actually a splitting pattern that matches only the delimiter. The delimiter pattern really is just :.

PHP snippet

Given this:

$text = <<<EOT
Company Name: Name of the company, place.
Company Address: Some, address, here.
Link: http://www.somelink.com
EOT;

preg_match_all('/^([^:]*):(.*)$/m', $text, $matches, PREG_SET_ORDER);

print_r($matches);

The output is (as seen on ideone.com):

Array
(
    [0] => Array
        (
            [0] => Company Name: Name of the company, place.
            [1] => Company Name
            [2] =>  Name of the company, place.
        )

    [1] => Array
        (
            [0] => Company Address: Some, address, here.
            [1] => Company Address
            [2] =>  Some, address, here.
        )

    [2] => Array
        (
            [0] => Link: http://www.somelink.com
            [1] => Link
            [2] =>  http://www.somelink.com
        )

)

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