PHP函数将“http：//”添加到字符串

Question

I often use the following code on my WordPress builds in order to help prevent invalid links being added:

// add http:// if necessary
function addHttp($url) {
    if(substr($url, 0, 4) == 'www.') {
        $url = 'http://' . $url;
    }
    return $url;
}

But this won't work should anyone add a link that does include a 'http://' but doesn't include a 'www.' in there too.

Does anyone know how I can modify my script to cater for this?

Answer 1

1. Don't assume that a URL will have www in it. Adding it will often break URLs.
2. Test to see if it starts with http or https and add the scheme if it doesn't

So:

function addHttp($url) {
  if(substr($url, 0, 4) != 'http') {
    $url = 'http://' . $url;
  }
  return $url;
}