PHP preg_split，同时在数组元素的开头保留定界符 [英] PHP preg_split while keeping delimiter at the start of array element

问题描述

我是regex的新手，我想在分隔符上拆分字符串，同时在每个数组元素的开头保留该分隔符.我尝试失败，然后想到了:

I'm new to regex, and I want to split a string on a delimiter, while keeping that delimiter at the beginning of each array element. I tried it unsuccessfully, and came up with:

    $str = 'LOTS OF STUFF AND SOME MORE STUFF AND SOME OTHER STUFF';
    $matches = preg_split('/(\ AND)/', $str, null, PREG_SPLIT_DELIM_CAPTURE);  

这会将分隔符作为其自己的元素:

This puts the delimiter as its own element :

[0]=>"LOTS OF STUFF"
[1]=>" AND"
[2]=>" SOME MORE STUFF"
[3]=>" AND"
[4]=>" SOME OTHER STUFF"

但是我想将定界符保留在元素的开头:

But I wanted to keep the delimiter at the beginning of the element:

[0]=>"LOTS OF STUFF"
[1]=>" AND SOME MORE STUFF"
[2]=>" AND SOME OTHER STUFF"

我想也许我可以尝试使用后向方式，但是后来我又失去了分隔符:

I thought maybe I could do it trying to use a look-behind, but then I was losing the delimiter again:

    $matches = preg_split('/(?<=\s)AND/', $str, null, PREG_SPLIT_DELIM_CAPTURE);

[0]=>"LOTS OF STUFF"
[1]=>" SOME MORE STUFF"
[2]=>" SOME OTHER STUFF"

希望得到一些帮助，谢谢！

Would love some help, thanks!!

推荐答案

使用 超前断言 ((?=))在跟在的字符串位置处被AND分开:

Use lookahead assertion ((?=)) to split at the string positions followed by AND:

$str = 'LOTS OF STUFF AND SOME MORE STUFF AND SOME OTHER STUFF';
$matches = preg_split('/ (?=AND)/', $str); 
var_dump($matches);
/*
array(3) {
  [0]=>
  string(13) "LOTS OF STUFF"
  [1]=>
  string(19) "AND SOME MORE STUFF"
  [2]=>
  string(20) "AND SOME OTHER STUFF"
}
*/  

演示 .此代码删除AND之前的空格；如果这不是您想要的，那就摆脱正则表达式中的空白.

Demo. This code removes whitespace preceding AND; if it's not what you want, just get rid off the whitespace in the regex.

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