Question

I have a string in PHP that is a URI with all arguments:

$string = http://domain.com/php/doc.php?arg1=0&arg2=1&arg3=0

I want to completely remove an argument and return the remain string. For example I want to remove arg3 and end up with:

$string = http://domain.com/php/doc.php?arg1=0&arg2=1

I will always want to remove the same argument (arg3), and it may or not be the last argument.

Thoughts?

EDIT: there might be a bunch of wierd characters in arg3 so my prefered way to do this (in essence) would be:

$newstring = remove $_GET["arg3"] from $string;

Answer 1

There’s no real reason to use regexes here, you can use string and array functions instead.

You can explode the part after the ? (which you can get using substr to get a substring and strrpos to get the position of the last ?) into an array, and use unset to remove arg3, and then join to put the string back together.:

$string = "http://domain.com/php/doc.php?arg1=0&arg2=1&arg3=0";
$pos = strrpos($string, "?"); // get the position of the last ? in the string
$query_string_parts = array();

foreach (explode("&", substr($string, $pos + 1)) as $q)
{
  list($key, $val) = explode("=", $q);
  if ($key != "arg3")
  {
    // keep track of the parts that don't have arg3 as the key
    $query_string_parts[] = "$key=$val";
  }
}

// rebuild the string
$result = substr($string, 0, $pos + 1) . join($query_string_parts);

See it in action at http://www.ideone.com/PrO0a