仅当术语位于其自己的行上时才将其删除

Question

我有这个：

$text = '

   hello world

    

    hello

';

如何删除它，只有当它在自己的线上？因此，在上面的例子中，第二个应该被删除。结果应为：  

$text = '

   hello world

    hello

';

到目前为止，我尝试过什么

通过，我可以：str_replace()

$text = str_replace(' ', '', $text);

但是，这将删除 的所有实例，而不仅仅是当它位于自己的行上时。 

Answer 1

我已经尝试过这种方法，我得到了你想要的输出// Your initial text$text = '   hello world        hello';// Explode the text on each new line and get an array with all lines of the text$lines = explode("\n", $text);// Iterrate over all the available linesforeach($lines as $idx => $line) {    // Here you are free to do any if statement you want, that helps to filter    // your text.    // Make sure that the text doesn't have any spaces before or after and     // check if the text in the given line is exactly the same is the      if ( ' ' === trim($line) ) {        // If the text in the given line is   then replace this line         // with and emty character        $lines[$idx] = str_replace(' ', '', $lines[$idx]);    }}// Finally implode all the lines in a new text seperated by new lines.echo implode("\n", $lines);我在本地的输出是这样的：hello world hello

Answer 2

我的方法是：在新行上分解文本修剪数组中的每个值清空每个具有值的数组项 用新线内爆生成以下代码：$chunks = explode(PHP_EOL, $text);$chunks = array_map('trim', $chunks);foreach (array_keys($chunks, ' ') as $key) {    $chunks[$key] = '';}$text = implode(PHP_EOL, $chunks);

Answer 3

也许是这样的：$text = preg_replace("~(^[\s]?|[\n\r][\s]?)(&nbsp;)([\s]?[\n\r|$])~s","$1$3",$text);http://sandbox.onlinephpfunctions.com/code/f4192b95e0e41833b09598b6ec1258dca93c7f06（这适用于 PHP5，但在某些版本的 PHP7 上却不起作用)替代方案是：<?php&nbsp; &nbsp; $lines = explode("\n",$text);&nbsp; &nbsp; foreach($lines as $n => $l)&nbsp; &nbsp; &nbsp; &nbsp; if(trim($l) == '&nbsp;')&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; $lines[$n] = str_replace('&nbsp;','',$l);&nbsp; &nbsp; $text = implode("\n",$lines);?>

Answer 4

如果您知道行尾字符，并且您的行后始终跟着一个新行：&nbsp;<?php$text = '&nbsp; &nbsp;hello&nbsp;world&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;hello';print str_replace("&nbsp;\n", "\n", $text);输出（此处的格式设置中丢失了一些初始空格）：&nbsp; &nbsp;hello&nbsp;world&nbsp; &nbsp;&nbsp;hello警告：任何以其他内容结尾的行也会受到影响，因此这可能不能满足您的需求。&nbsp;

Answer 5

为此，您可以使用正则表达式，将 DOTALL 和多行修饰符与环视断言结合使用：preg_replace("~(?sm)(?<=\n)\s*&nbsp;(?=\n)~",&nbsp;'',$text);(?sm)： 多点 （s） 多线 （m）(?<=\n)：换行符之前（不是匹配项的一部分）\s*&nbsp;\s*： 单次具有可选的周围空格(?=\n)：尾随换行符（不是匹配项的一部分）>>> $text = '&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;hello&nbsp;world&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;&nbsp;hello&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp;';=> """&nbsp; &nbsp;\n&nbsp; &nbsp; &nbsp; hello&nbsp;world\n&nbsp; &nbsp; &nbsp; &nbsp;\n&nbsp; &nbsp; &nbsp; &nbsp;hello\n&nbsp; &nbsp;""">>> preg_replace("~(?sm)(?<=\n)\s*&nbsp;\s*(?=\n)~", '',$text);=> """&nbsp; &nbsp;\n&nbsp; &nbsp; &nbsp; hello&nbsp;world\n&nbsp; &nbsp;\n&nbsp; &nbsp; &nbsp; &nbsp;hello\n&nbsp; &nbsp;""">>>