php - 如何使用 PHP 正则表达式压缩空格字符？

Question

$string = 'Hello    this is a bunch of numbers: 333 and letters and $pecial Characters@!*(';

$foo = preg_replace("/[^a-zA-Z0-9\s]/", "", $string);

echo $foo;

以上返回:

Hello    this is a bunch of numbers 333 and letters and pecial Characters

我想保留空格，但如果有多个空格则不会。怎么办？

它应该是这样的:

Hello this is a bunch of numbers 333 and letters and pecial Characters

Answer 1

$foo = preg_replace("/[^a-zA-Z0-9\s]/", "", $string);
$foo = preg_replace('/\s+/',' ',$foo);