PHP Zero integer is being evaluated as false

Question

As the title says, PHP seems to be evaluating the integer value 0 as false.

Take for example this snippet:

http://sandbox.onlinephpfunctions.com/code/13d885fb68359a3154999c2ef85db7c913c49bc5

<?php

if($exists = checkDup()){
    echo $exits;
}
else{
    echo "error!";  
}

function checkDup ($foo = 'blah', $bar = 'blah'){
    if ($foo == $bar) return (int) 0;
    return false;
}

As you can see, despite casting the reply as an int PHP parsing the return as false which in incorrect.

Because that's what it is flagged as.. return it as "0"

clearshot66
– clearshot66

2017-04-07 16:27:47 +00:00
Commented Apr 7, 2017 at 16:27 — clearshot66
– clearshot66, Commented Apr 7, 2017 at 16:27

sfeldmann · Accepted Answer · 2017-04-07 16:35:42Z

5

PHP is evaluating a lot to false ;) For example null, '', 0 You have to include a type check as well, you can do so by using === or !==

$exists = checkDup();
if($exists !== false){
    echo $exits;
}
else{
    echo "error!";  
}

function checkDup ($foo = 'blah', $bar = 'blah'){
    if ($foo == $bar) return 0;
    return false;
}

answered Apr 7, 2017 at 16:35

sfeldmann

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Comments

Diogo Sgrillo · Accepted Answer · 2017-04-07 16:34:15Z

2

You should use if($exists = checkDup() !== false)

0 == false; //true

0 === false; //false

When you don't specify the a boolean expression in the if, it will execute the == operator

answered Apr 7, 2017 at 16:34

Diogo Sgrillo

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