正则表达式 (PHP) 匹配从字符串开头开始或前面有空格+数字+/+空格的所有内容

Question

我有一个看起来像这样的字符串：1/ This is a string and it                                                                                   has some text on a new line2/ And then there's another string that has text only on one line532/ Another string that has some year on a new line 2020/xyz followed by some letters720/ This is a match on the same line with another match but the other match won't be captured 721/ And this is the last line \d我想捕获以小于或等于 3 dgits long( ) 的数字 ( {1,3}) 开头并具有正斜杠 ( /) 并且位于字符串开头或前后有空格或换行符的每个字符串( \s+).这就是我希望它看起来像的样子：[Match 1] 1/ This is a string and it has some text on a new line[Match 2] 2/ And then there's another string that has text only on one line[Match 3] 532/ Another string that has some year on a new line 2020/xyz followed by some letters[Match 4] 720/ This is a match on the same line with another match but the other match won't be captured[Match 5] 721/ And this is the last line 到目前为止，这是我的代码：$re = '/(\s|^)(?s)\d{1,3}+\/+\s+.*?(?=\d+\/+\s+|$)/m';$str = '1/ This is a string and it has some text on a new line2/ And then there\'s another string that has text only on one line532/ Another string that has some year on a new line2020/xyz followed by some letters721/ And this is the last line ';preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);// Print the entire match resultvar_dump($matches);这是一个演示但是这里有问题：如果两个匹配项在同一行上，它将不会捕获字符串（匹配 4 和 5 只会捕获匹配 4）它不捕获新行上的字符串它不会捕获字符串中有数字后跟 / 的部分，例如2020/xyz followed by some letters

Answer 1

$将与行尾匹配的锚点（使用 m 修饰符）更改为\z锚点（无论修饰符如何匹配字符串的末尾）。

这样，不情愿的量词.*?将能够匹配多行，而不是停在行的第一端。

要在同一行中查找多个匹配项，请\s+在数字前添加前瞻。否则数字之前的空间不能被消耗两次（一次被.*?一次被 消耗一次(\s|^)）。

~(\s|^)\d{1,3}/+\s.*?(?=\s+\d{1,3}/+\s|\z)~ms

请注意，您可以使用以下方法获得修剪结果：

~(?<!\S)\d{1,3}/+\s.*?(?=\s+\d{1,3}/+\s|\s*\z)~s

要减少步骤数，您可以更改\s.*?并(?>\s+\S+)*?删除不再需要的 s 修饰符。

Answer 2

尝试：

(?:\s|^)\d{1,3}\/\s(?:(?!\s\d{1,3}\/\s)[\s\S])*

请参阅正则表达式演示

<?php

$str = "1/ This is a string and it

has some text on a new line

2/ And then there's another string that has text only on one line

532/ Another string that has some year on a new line

2020/xyz followed by some letters

720/ This is a match on the same line with another match but the other match won't be captured 721/ And this is the last line";

preg_match_all('/(?:\s|^)\d{1,3}\/\s(?:(?!\s\d{1,3}\/\s)[\s\S])*/', $str, $matches, PREG_SET_ORDER);

print_r($matches);

印刷：

Array

(

    [0] => Array

        (

            [0] => 1/ This is a string and it

has some text on a new line

        )

    [1] => Array

        (

            [0] =>

2/ And then there's another string that has text only on one line

        )

    [2] => Array

        (

            [0] =>

532/ Another string that has some year on a new line

2020/xyz followed by some letters

        )

    [3] => Array

        (

            [0] =>

720/ This is a match on the same line with another match but the other match won't be captured

        )

    [4] => Array

        (

            [0] =>  721/ And this is the last line

        )

)