How to Read and Get URL Parameters in PHP

• Getting & Extracting URL Query Parameters in PHP
• What are URL parameters / query strings?
• PHP’s built‑in mechanism: $_GET
• Extracting from an arbitrary URL string
  • parse_url() + parse_str()
  • Regex alternative
• Getting the full current URL
• Helper functions
• Edge Cases & Best Practices
• Summary

Getting & Extracting URL Query Parameters in PHP

When building PHP web applications, it's very common to need to read values passed via the URL (the “query string” or GET parameters). In this post, we'll cover:

• What URL parameters (query strings) are
• How PHP makes them available
• How to parse parameters from a URL string
• Useful helper functions
• Edge cases, security, and best practices

What are URL parameters / query strings?

A URL parameter (or query string) is the portion of a URL after the ? character, with key/value pairs separated by &. For example:

https://example.com/search.php?q=php&lang=en&page=2

Here:

• q = php
• lang = en
• page = 2

These are traditionally accessed via HTTP GET. They allow passing small amounts of data in the URL itself.

PHP’s built‑in mechanism: $_GET

The simplest and most common way to access URL parameters in PHP is via the superglobal $_GET. This is an associative array that PHP fills from the query string of the current request.

<?php
// Suppose URL is: http://mysite.com/page.php?user=alice&age=30
 
$user = $_GET['user'];  // “alice”
$age  = $_GET['age'];   // “30”
 
// Better: check existence
if (isset($_GET['user'])) {
    $user = $_GET['user'];
} else {
    $user = null;
}
?>

You can also use the null coalescing operator (PHP 7+):

$user = $_GET['user'] ?? null;

With filtering:

$user = filter_input(INPUT_GET, 'user', FILTER_SANITIZE_STRING);

Notes:

• $_GET works whenever a query string is present, regardless of request method.
• Always validate and sanitize data.
• Use isset(), ??, or filter_input() to avoid notices.
• Arrays (?arr[]=foo&arr[]=bar) are automatically handled.

Extracting from an arbitrary URL string

Sometimes you need to parse parameters from a URL string, not the current request. In that case:

parse_url() + parse_str()

<?php
$url = "https://example.com/path?foo=bar&baz=qux&arr[]=one&arr[]=two";
 
$parts = parse_url($url);
 
if (!empty($parts['query'])) {
    parse_str($parts['query'], $queryParams);
    // ["foo"=>"bar", "baz"=>"qux", "arr"=>["one", "two"] ]
} else {
    $queryParams = [];
}
?>

Or shorter:

parse_str(parse_url($url, PHP_URL_QUERY), $queryParams);

Cautions:

• Don’t call parse_str() without the second argument, it pollutes the local scope.
• Spaces/dots in keys become underscores.
• max_input_vars can limit the number of parameters parsed.

Regex alternative

if (preg_match("/[?&]foo=([^&]+)/", $url, $matches)) {
    $fooVal = urldecode($matches[1]);
}

But this is brittle, built‑ins are preferred.

Getting the full current URL

If you need the complete current request URL:

<?php
function getCurrentUrl(): string {
    $scheme = isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on' ? "https" : "http";
    $host = $_SERVER['HTTP_HOST'];
    $uri  = $_SERVER['REQUEST_URI'];
    return $scheme . "://" . $host . $uri;
}
 
$current = getCurrentUrl();
echo $current;
?>

This gives something like:

https://example.com/search.php?lang=en&q=php

Helper functions

<?php
function getQueryParams(?string $url = null): array {
    if ($url === null) {
        $qs = $_SERVER['QUERY_STRING'] ?? '';
        parse_str($qs, $params);
        return $params;
    }
 
    $parts = parse_url($url);
    if (empty($parts['query'])) {
        return [];
    }
 
    parse_str($parts['query'], $params);
    return $params;
}
 
function getParam(string $key, ?string $url = null, $default = null) {
    $params = getQueryParams($url);
    return $params[$key] ?? $default;
}
?>

Usage:

$params = getQueryParams("https://example.com/?a=1&b=2");
$email  = getParam('email', null, '');

Edge Cases & Best Practices

Summary

1. Use $_GET for current request parameters.
2. Use parse_url() + parse_str() for arbitrary URLs.
3. Encapsulate parsing in helpers.
4. Always validate and sanitize input.