替换非字母数字字符的所有组合

Question

I need to to create url from various strings.
So trying to replace all non-alphanumeric characters and all of their combinations - with a hyphen character ( - )

$string = "blue - sky";
$string = preg_replace("/[^A-Za-z0-9 ]/", '-', $string);
echo $string;  

result - blue---sky
expected - blue-sky .

Answer 1

使用+符号用一个替换字符替换多个字符：

string = preg_replace("/[^A-Za-z0-9]+/", '-', $string);