在读取/使用变量之前，是否总是需要检查是否设置了post和get变量？

Question

Consider the following example:

if ( isset($_POST['type']) && 'page' == $_POST['type'] )
    return;

Do we need the isset($_POST['type']) check?

From what I've seen so far the following has the seem result:

if ( 'page' == $_POST['type'] )
    return;

Or can this cause problems in certain situations?

Answer 1

Using " isset " is right approach otherwise it will throw warning: "index type is undefined". Also it checks whether array is empty or not.

isset() function will serve the replacement of two functions

if(!empty(your_array) && array_key_exists('type',$POST['type']))

So use this check to avoid further complications

Answer 2

This can cause problems like error notice: PHP: "Notice: Undefined variable", "Notice: Undefined index", and "Notice: Undefined offset"

You can use array_key_exists instead of isset . array_key_exists method will definitely tell you if a key exists in an array, whereas isset will only return true if the key/variable exists and is not null

There is another important difference. isset doesn't complain when $x does not exist, while array_key_exists does.

$x = [
    'key1' => 'abcd',
    'key2' =>  null
];

isset($x['key1']);             // true
array_key_exists('key1', $x);  // true

isset($x['key2']);             // false
array_key_exists('key2', $x);  // true