<?php $str = " This line contains\tliberal \r\n use of whitespace.\n\n"; // First remove the leading/trailing whitespace //去掉开始和结束的空白 $str = trim($str); // Now remove any doubled-up whitespace //去掉跟随别的挤在一块的空白 $str = preg_replace('/\s(?=\s)/', '', $str); // Finally, replace any non-space whitespace, with a space //最后，去掉非space 的空白，用一个空格代替 $str = preg_replace('/[\n\r\t]/', ' ', $str); // Echo out: 'This line contains liberal use of whitespace.' echo "<pre>{$str}</pre>"; ?>