使用URL中的错误$ _GET参数时出错

Question

and can't get this to work. I want to get variable from URL, like:

domain.com?region=STATE

if (empty($_GET)) {
    echo 'American';

}

else {
    $t = $_GET["region"];
    if ($t == "Texas") {
        echo "Texan";
    } elseif ($t == "California") {
        echo "Californian";
    } else {
        echo "American";
    }
}

This does work. However in case there's wrong parameter input, like:

domain.com?asdasd=whatever

I get an error:

"Notice: Undefined index: region in test.php on line 19"

Can you tell me how can I prevent this error from appearing and basically treat it as empty variable and return "American" instead?

I tried this code, but it doesn't work:

if (empty($_GET)) {
    echo 'American';

}
elseif ($_GET != "region") {
    echo 'Anything Else';
}
else {
    $t = $_GET["region"];
    if ($t == "Texas") {
        echo "Texan";
    } elseif ($t == "California") {
        echo "Californian";
    } else {
        echo "American";
    }
}

Even if URL is true:

domain.com?region=Texas

is still get "Anything Else" in the output.

Answer 1

Use isset(($_GET['region']) as it does not emit a notice if fed an undefined variable:

if (!isset($_GET['region'])) {
    echo 'American';
} else {
    $t = $_GET["region"];
    if ($t == "Texas") {
        echo "Texan";
    } elseif ($t == "California") {
        echo "Californian";
    } else {
        echo "American";
    }
}