| Re: Booleans compared to strings [message #181356 is a reply to message #181348] |
Mon, 13 May 2013 15:22   |
Thomas 'PointedEars'
Messages: 701
Registered: October 2010
Karma:
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Senior Member |
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Jerry Stuckle wrote:
> On 5/13/2013 8:29 AM, Doug Cassidy wrote:
>> So, this is wierd:
>>
>> $b = true;
>> var_dump($b);//boolean true
>>
>> if(!$b)echo '!$b I wont echo, correctly so<BR>';
>> if($b)echo '$b I will echo, correctly so<BR>';
>>
>> if($b == 'false')echo '$b == I will echo, which is wrong<BR>';
>> if($b === 'false')echo '$b === I wont echo, which is correct<BR>';
>>
>> if($b == 'true')echo '$b == I will echo, which is kinda correct<BR>';
>> if($b === 'true')echo '$b === I wont echo, which is very correct<BR>';
>>
>> Yes, I know that 'true' and 'false' are strings, not bool.
>>
>> this one:
>> if($b == 'false')echo '$b == I will echo, which is wrong<BR>';
>>
>> I dont see why boolean true is equal to string false in any way.
>
> A string comparison returns false only if the string is NULL, is an
> empty string ('') or contains a zero ('0'). All other values (including
> 'false') are true.
The reason for this is type juggling, not “string comparison”.
What you might have meant is how a string value in a type-converting
conditional expression is evaluated (like that of “if ($string)” or
“($string) ? … : …”), where type juggling is performed as well.
PointedEars
--
var bugRiddenCrashPronePieceOfJunk = (
navigator.userAgent.indexOf('MSIE 5') != -1
&& navigator.userAgent.indexOf('Mac') != -1
) // Plone, register_function.js:16
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