Edit report at https://bugs.php.net/bug.php?id=54547&edit=1
ID: 54547
Comment by: ni...@php.net
Reported by: peter dot ritt at gmx dot net
Summary: wrong equality of string numbers
Status: Verified
Type: Bug
Package: Unknown/Other Function
Operating System: linux
PHP Version: 5.3.6
Assigned To: dmitry
Block user comment: N
Private report: N
New Comment:
@Jeff Please see jabakobob's comment why doing just a string comparison can be
counterproductive. Remember: PHP is mainly used around the HTTP protocol (where
everything is a string) and MySQL (where also everything is returned as a
string). So in PHP you will often deal with numbers in strings, thus they
should be handled as such.
Previous Comments:
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[2012-04-12 14:02:02] Jeff at bobmail dot info
That didn't address my comment. Why wouldn't the internal implementation check
to see if the strings are the same? When doing a comparison and the internal
data type is a string, wouldn't that be faster and most correct?
In all honesty I would prefer PHP's "loosely typed" system mimic JavaScript's
in that any type can be put anywhere but the object still keeps its type
information for situations just like this.
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[2012-04-12 13:59:32] ni...@php.net
@Jeff: You have to understand in PHP 1, 1.0 and "1.0" all are equivalent (in
most situations). That's by design.
E.g. GET and POST variables are always strings, even if you put numbers into
them (as per the HTTP standard). PHP obviously wants those GET/POST variables
to still be useable just like they were numbers, that's why "1" and 1 can be
used interchangeably throughout PHP.
In that context - in my eyes - this comparison also makes sense. Consider a
very similar comparison:
var_dump('0.1' == '0.10000000');
What would you expect to be the output - if you remember that in PHP numeric
strings and actual numbers are interchangeable? Clearly it has to behave
exactly as if you had written:
var_dump(0.1 == 0.10000000); // => bool(true)
In most cases this type of comparison is what you want and it usually works
exactly as expected.
What you see here in this issue is one of the edge cases (how often do you use
large numbers in PHP?) where it does not work well.
I hope you understand that it is not viable to remove a handy feature from PHP,
just because it fails under certain edge case conditions.
If you want to use a strict string comparison, just use ===.
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[2012-04-12 13:58:53] paj...@php.net
@Jeff at bobmail dot info
that's what === is for (real comparisons without casting).
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[2012-04-12 13:51:22] jabakobob at gmail dot com
The conversion to a number is necessary because programmers don't differentiate
between strings and numbers in PHP. Consider the following code:
if ($_GET["a"] == $_GET["b"]) echo "a is same as b!";
The result will be the same if the query string is ?a=1&b=1 or ?a=1&b=1.0 or ?
a=01&b=1 because PHP is loosely typed.
Internally $_GET["a"] and $_GET["b"] are both strings, but we can't do a string
comparison. If you want a string comparison, use strcmp.
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[2012-04-12 13:31:42] Jeff at bobmail dot info
I'm confused as to why there is even a conversation around "should we fix this".
The data objects are strings. Sure, PHP is "loosely typed" but shouldn't it do
the comparison you tell it to do first before attempting anything else?
I agree with the previous suggestion: make it a real string comparison and drop
the type casting.
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the rest of the comments, please view the bug report online at
https://bugs.php.net/bug.php?id=54547
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