Edit report at https://bugs.php.net/bug.php?id=39579&edit=1
ID: 39579
User updated by: iain at workingsoftware dot com dot au
Reported by: iain at workingsoftware dot com dot au
Summary: Comparing zero & string values in boolean comparison
has unexpected behaviour
Status: Not a bug
Type: Bug
Package: Variables related
Operating System: FreeBSD 6.1
PHP Version: 5.2.0
Block user comment: N
Private report: N
New Comment:
Hi, I agree this shouldn't be changed. It's pretty fundamental to how PHP works
and since reporting this bug 6
years ago I've learned a lot more about PHP :)
I still think my suggestion of emitting a Notice whenever a string is converted
to 0 as a result of being
evaluated in a numeric context isn't too outlandish though.
*Changing* the way that strings are evaluated would break a buttload of code
and
isn't really productive.
Emitting a Notice would help people unfamiliar with the implicit typecasting
behaviour save some time and
avoid bugs when developing. For those that like to write "clean code" with no
Notices there is a very simple
way of suppressing it (ie. use === or (int)).
Also, emitting a notice wouldn't actually break any code, although it might
cause a number of scripts out in
the wild to become more verbose in their logging - is that not an acceptable
risk?
The notice could even say something like:
Notice: String evaluated to 0 (zero) when used in numeric context on line
WHATEVER. Use === or (int) to
prevent this notice.
This would enable people to quickly understand the behaviour (which is kind of
unintuitive but fair enough
when you look at PHPs type system - just a foible of the language everyone
should learn) and encourage people
to learn the importance of === earlier on.
Previous Comments:
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[2013-02-14 17:26:40] radamanf at gmail dot com
I've seen a topic in the web:
http://josephscott.org/archives/2012/03/why-php-strings-equal-zero/ related to
this bug, and I can see that sometimes string need to be compared with integer
as integer BUT this is a huge pool of potential bugs across all the worldwide!
:) Can you imagine how many people usign PHP without realizing this BUG ! :)_)
I'm sure this is a loved BUG by most hackers out there !
------------------------------------------------------------------------
[2013-02-14 17:24:51] [email protected]
@radamanf: Stop shouting. Shouting does not help.
I agree that this behavior ('foo' == 0) is counter-productive. I think most
people would agree on that. But even if everyone agrees that it's the wrong
behavior, changing it isn't so easy. Changing this behavior will probably break
existing software.
If you really want to change this, then there is only one way: Make the change
and then test a shitload of code against it. See how many tests will fail in
major PHP projects and how easy things are to fix.
If you can provide sufficient data that this change (which goes rather deep
into the core semantics of the language) won't affect existing projects
heavily, then I see no problem with doing it.
------------------------------------------------------------------------
[2013-02-14 17:14:35] radamanf at gmail dot com
Related To: Bug #39579
------------------------------------------------------------------------
[2013-02-14 17:14:35] radamanf at gmail dot com
This is a epic FAIL in pure logic of comparing formats not having explicitly
defining them, whole beauty of PHP disappear! This is BROKEN LOGIC.
Connected BUGS
Bug #44990
Bug #39579
Different people are coming across this BUG and thinking the same as me, so
please CHANGE your documentation, it's WRONG! Who is this "GENIES" to make
possible converting String to Integer NOT INT TO STRING!
Guys, I'm very disappointed! :)
------------------------------------------------------------------------
[2012-08-01 10:31:16] v dot picture at free dot fr
Hi, I'm wondering why this comparison should be evaluated in a numeric context
and not a string context, after all
there is no loss with string casting whereas there is a huge risk of doing
mistakes with numeric casting:
(string) 0 => "0"
(string) 42.5 => "42.5"
(int) "test" => 0
But ok, let's say it's a normal behavior.
"If you compare a number with a string or the comparison involves numerical
strings, then each string is converted to
a number"
Then why would PHP decide to do that in a string context ? I mean, when I
compare two strings I don't expect PHP to
convert everything to numbers !
"10" == "1e1" => true
Sorry folks, this really seems like a string context to me.
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