difference between != and !==

Question

In my case should I use != as below, or is !== more appropriate, what is the difference.

private function authenticateApi($ip,$sentKey) {

    $mediaServerIp = '62.80.198.226';
    $mediaServerKey = '45d6ft7y8u8rf';        

    if ($ip != $mediaServerIp ) {
        return false
    }
    elseif ($sentKey != $mediaServerKey ) {
        return false
    }
    else {
        return true;
    }
}

public function setVideoDeletedAction(Request $request)
{
    //Authenticate sender
    if ( $this->authenticateApi($request->server->get("REMOTE_ADDR"),$request->headers->get('keyFile')) != true ) {
       new response("Din IP [$ip] eller nyckel [********] är inte godkänd för denna åtgärd.");
    }

Loose equality is a security hole for you: http://codepad.org/0j4T3iCl. — Blender, Dec 20 '13 at 17:56
@Blender You are so wrong, couldn't you at least test the code for yourself? the linked page is stupid — Alireza Fallah, Dec 20 '13 at 18:06
So since I have full control over the return value (from authenticateApi() ) it is not a security hole for me there? but might be a problem inside the authenticateApi() since I pull in values from the request-object? — Matt Welander, Dec 20 '13 at 18:11
@MattiasSvensson: My point is that loose inequality does more than check strings for equality (for example, `"0000002" == "2"`), which is not something you want. — Blender, Dec 20 '13 at 18:16

score 2 · Accepted Answer · answered Dec 20 '13 at 17:56

2

!= checks value

if($a != 'true')

!== checks value and type both

if($a !== 'true')

answered Dec 20 '13 at 17:56

Adil Abbasi

2,857
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1

Perhaps in the second case you meant `if ($a !== 'true')`? – briosheje Dec 20 '13 at 17:57
yes, I have updated it. – Adil Abbasi Dec 20 '13 at 17:58

score 1 · Answer 2 · answered Dec 20 '13 at 17:56

1

http://www.php.net/manual/en/language.operators.comparison.php

As the manual says, one compares type as well.

answered Dec 20 '13 at 17:56

Jessica

7,019
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score 0 · Answer 3 · answered Dec 20 '13 at 17:55

0

!== is more strict. '1'==1 returns true, but '1'===1 - false, because of different types.

answered Dec 20 '13 at 17:55

BaBL86

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score 0 · Answer 4 · answered Dec 20 '13 at 17:59

=== and !== are used to compare objects that might be of different type. === will return TRUE iff the types AND values are equal; !== will return TRUE if the types OR values differ. It is sometimes known as the 'congruency' operator.

If you are comparing two things that you know will always be the same type, use !=.

Here's an example of using !==. Suppose you have a function that will return either an integer or the value FALSE in the event of a failure. 0 == FALSE, but 0 !== FALSE because they are different types. So you can test for FALSE and know an error happened, but test for 0 and know you got a zero but no error.

difference between != and !==

4 Answers4

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