[PHP] 解析 URL 字串 parse_url , parse_str

parse_url 會解析一個標準的 URL 字串

<?php
$urlStr="http://user:passwd@host:80/path?a1=v1&a2=v2#anchor";
$url=parse_url($urlStr);
print_r($url);
/* output:
Array
(
    [scheme] => http
    [host] => host
    [port] => 80
    [user] => user
    [pass] => passwd
    [path] => /path
    [query] => a1=v1&a2=v2
    [fragment] => anchor
)
*/

echo parse_url($url, PHP_URL_SCHEME);
// prints:  http

echo parse_url($url, PHP_URL_HOST);
// prints: host

echo parse_url($url, PHP_URL_PORT);
// prints: 80

echo parse_url($url, PHP_URL_USER);
// prints: user

echo parse_url($url, PHP_URL_PASS);
// prints: passwd

echo parse_url($url, PHP_URL_PATH);
// prints: /path

echo parse_url($url, PHP_URL_QUERY);
// prints: a1=v1&a2=v2

echo parse_url($url, PHP_URL_FRAGMENT);
// prints: anchor

?>

parse_str 會解析 URL Query 格式的字串
這裡特別注意，別使用下面的第一種方式直接解析 URL 上的 query
這會造成資安上的漏洞，這會讓外部可以直接修改裡面的變數值

<?php
$url_query = "city=new+york&id=3456&paid%5Bcurrency%5D=euro&paid%5Bamount%5D=345&paid%5Breceipt%5D=fgf"
parse_str($url_query);

echo $city;
// prints: new york

echo $id;
// prints: 3456

print_r($paid);
/* output:
Array
(
    [currency] => euro
    [amount] => 345
    [receipt] => fgf
)
*/

/* 不建議上面的作法，因為會複寫原本的變數
 * 造成資安上的漏洞
 * */

parse_str($url_query, $query);
print_r($query);
/* output :
Array
(
    [city] => new york
    [id] => 3456
    [paid] => Array
    (
        [currency] => euro
        [amount] => 345
        [receipt] => fgf
    )

)*/
?>

參考來源：
Easy way to build GET query strings in php