如何使用preg_replace在缺少这些子字符串的URL中添加“www”和“http：//”？

Question

I want to make this by the preg_replace:

$web = 'example.com';

I want the preg_replace make it http://www.example.com and if it http://example.com no problem. It should add http:// in it found in the URL.

I want do that is http:// not exist.

Answer 1

preg_replace("/^(?:http:\/\/)?(.*)/","http://$1",$web);