我将结合使用 preg_replace 和 trim :

I would use a combination of preg_replace and trim:

trim(preg_replace('/-+/', '-', $str), '-')

preg_replace调用会删除多个破折号，而trim会删除前导和尾随破折号.

The preg_replace call removes multiple dashes and trim removes the leading and trailing dashes.