How to understand OR operator in a PHP statement

Question

I have a below PHP statement:

   if( 
        (bool)is_check1($a) || 
        (bool)is_check2($a) || 
        (bool)is_check3($a)
    ){
        callFunctionA();
    }

I have debugged and got a news thing so strange that, even if is_check1 returns TRUE, PHP still invoke the functions: is_check2, and is_check3.

In my mind, I always think that, if is_check1 function returns TRUE, PHP SHOULD not invoke others.

But when I check it again, for example:

   if( 
        TRUE ||
        (bool)is_check2($a) || 
        (bool)is_check3($a)
    ){
        callFunctionA();
    }

The result is: is_check2 and is_check3 function do not invoke.

Please give me your advice to optimize in this case or am I missing something?

This would not be possible. Something else is going on. Can you post a working example on e.g. ideone.com? — Jon, Sep 15 '11 at 12:38
There is no point in those `(bool)` casts. They shouldn't break it but are unecessary, since in that situation the return values would be evaluated as booleans anyway. — DaveRandom, Sep 15 '11 at 12:40
Now, I got this problem. This point is my function returns incorrectly. Thanks so much for all of your help. — vietean, Sep 15 '11 at 12:55

Wesley van Opdorp · Accepted Answer · 2011-09-15T12:52:19.433

5

Attempting to reproduce with the following code:

function a() { echo 'a'; return true; }
function b() { echo 'b'; return true; }
function c() { echo 'c'; return true; }

if (a() || b() || c()) echo 'valid!';
if (true || b() || c()) echo 'valid!';
if ((bool)a() || (bool)b() || (bool)c()) echo 'valid!';

Prints: avalid!valid!avalid!

That means the problem is probably the return values of your functions.

edited Sep 15 '11 at 12:52

answered Sep 15 '11 at 12:47

Wesley van Opdorp

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+1: [Beat me to it](http://codepad.org/E3O0qNxu) – Lightness Races in Orbit Sep 15 '11 at 12:48
I think the result SHOULD be: `avalid!valid!avalid!` – vietean Sep 15 '11 at 12:51

How to understand OR operator in a PHP statement

1 Answers1