Question

How to make sure that a string contains a valid/well formed url?

I need be sure the url in the string is well formed.

It must contain http:// or https://

and .com or .org or .net or any other valid extension

I tried some of the answers found here in SO but all are accepting “www.google.com” as valid.

In my case the valid url needs to be http://http://www.google.com or https://http://www.google.com.

The www. part is not an obligation, since some urls dont use it.

Answer 1

Take a look at the answer here:
PHP regex for url validation, filter_var is too permisive

filter_var() could be just fine for you, but if you need something more powerful, you’ll have to use regex.

Additionally with the code from here, you can sub-in any regex that suits your needs:

<?php 
    $regex = "((https?|ftp)\:\/\/)?"; // SCHEME 
    $regex .= "([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?"; // User and Pass 
    $regex .= "([a-z0-9-.]*)\.([a-z]{2,3})"; // Host or IP 
    $regex .= "(\:[0-9]{2,5})?"; // Port 
    $regex .= "(\/([a-z0-9+\$_-]\.?)+)*\/?"; // Path 
    $regex .= "(\?[a-z+&\$_.-][a-z0-9;:@&%=+\/\$_.-]*)?"; // GET Query 
    $regex .= "(#[a-z_.-][a-z0-9+\$_.-]*)?"; // Anchor 
?> 

Then, the correct way to check against the regex list as follows: 

<?php 
       if(preg_match("/^$regex$/", $url)) 
       { 
               return true; 
       } 
?>