PHP：如何获取无密钥URL参数

Question

I would like to get the parameter in a key such as http://link.com/?parameter

I read somewhere that the key is NULL and the value would be parameter .

I tried $_GET[NULL] but it didn't seem to work.

Here is my code:

if ($_GET[NULL] == "parameter") {
    echo 'Invoked parameter.';
} else {
    echo '..';
}

It just prints out .. so that means I'm not doing it right. Can someone please show me the right way.

Answer 1

There are no such things as keyless URL parameters in PHP. ?parameter is the equivalent of $_GET['parameter'] being set to an empty string.

Try doing var_dump($_GET) with a url like http://link.com/?parameter and see what you get.

It should look something like this:

array (size=1) 'parameter' => string '' (length=0)

Thus, you can test it in a couple of ways depending on your application needs:

if (isset($_GET['parameter'])) {
   // do something
} else {
   // do something else
}

or

// Only recommended if you're 100% sure that 'parameter' will always be in the URL.
// Otherwise this will throw an undefined index error. isset() is a more reliable test.

if ($_GET['parameter'] === '') {
   // do something
} else {
   // do something else
}

Answer 2

$_GET is a super global assoc array, that contains parameter => it's value pairs. So, parameter is a key of the array.

For example, if your url is something like this: myweb.com/?page=load&do=magic than you $_GET is:

$_GET(
  [page] => load
  [do] => magic
)

If you want just to test, if parameter is in you URL as a param, you should do something like this:

if (isset($_GET['parameter'])
  echo "Here I am!";

Answer 3

You can also get the entire request_url like this

echo $_SERVER['REQUEST_URI'];

To get the part after ? :

echo explode('?', $_SERVER['REQUEST_URI'])[1];

Answer 4

You could via array_keys() :

$param = array_keys($_GET)[0];

Which would give you the name of the first querystring parameter, whether it has a value or not.

You could also get all of the parameters without a value like so:

$empty = [];
foreach($_GET as $key => $value)
    if(strlen($value) === 0) $empty[] = $key;

print_r($empty);

Answer 5

You can get the part of the URL beginning with ? with

$_SERVER['QUERY_STRING']