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From: "J.O. Aho" <user@example.net>
Newsgroups: comp.lang.php
Subject: Re: empty - not empty()
Date: Mon, 19 Dec 2011 18:48:53 +0100
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bill wrote:
> searching the manual gives lots of hits, none of which appear relevant (at
> least by the title).
>
> I had the following code in a scheduling class:
>
> if ($ptNum == "empty") {
> $ptNum = 0;
> $status= "e";
> }
>
> I pass the string "empty" to the function as a patient number if we are
> creating an empty appointment slot.
>
> now, this fails because with a patient number of 0 the if returns true.
>
> I am aware of the function empty() that would work like that, but do not
> understand why the compare fails with the constant, "empty."

I assume you are comparing 0 and not the string "0", this makes you are 
comparing integer with string, there ain't any type conversion done.
The zero is always equal to a string, there is a slightly more information at

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


> I fixed the function by making it a strict compare, but would like to know why
> the regular compare is true with the numeric value of zero.

I would say it's not the right way to compare, use strcmp, is_numeric and so 
on, to make a proper compare instead of using the comparison operator.


-- 

   //Aho