如何删除换行符后跟空格？

Question

我想删除所有换行符后跟一个空格或换句话说；将所有以空格开头的行移动到最后一行的末尾。

示例：

$str_before = "Lorem Ipsum is simply dummy text
 of the printing and typesetting industry. 
Lorem Ipsum has been the industry's 
standard dummy text ever since the";

想要的结果：

$str_after = "Lorem Ipsum is simply dummy text of the printing and typesetting industry. 
Lorem Ipsum has been the industry's 
standard dummy text ever since the";

我已经试过了，但没有成功：

$str_after = str_replace("\n"." "," ", $str_before)

如何使用 php/regex 实现此目的？

Answer 1

不是很优雅，但应该可以。

<?php

$str = 'Lorem Ipsum is simply dummy text
 of the printing and typesetting industry. 
Lorem Ipsum has been the industry\'s 
standard dummy text ever since the';

$newStr = []; $i = 0;
foreach(preg_split("/((\r?\n)|(\r\n?))/", $str) as $line) {
  $i++;

  if ($line[0] == chr(32)) {
    $newStr[$i-1] .= $line;
  } else {
    $newStr[$i] = $line;
  }
} 
echo implode(PHP_EOL, $newStr);

Answer 2

使用以下正则表达式：

^([^\n]*)\n( [^\n]*)$
Demo here.

在文件中找到匹配的所有内容。替换为连接在一起的第一个和第二个捕获组。

如何删除换行符后跟空格？

How do I remove linebreaks followed by a whitespace?

php

regex

preg-replace

str-replace