How can I convert two or more dashes to singles and remove all dashes at the beginning and end of a string?

Question

Example: -this--is---a-test--

What I want: this-is-a-test

Thanks for any answers! :)

Answer 1

Without regular expression....

$string = trim($string,'-');

while (stristr($string,'--')) {$c = str_ireplace('--','-',$string);}