(inline --and last post on this thread)
Adam Zey wrote:
Rafael wrote:
(inline)
Adam Zey wrote:
Rafael wrote:
A single "=" it's an assignment, not a comparison; and though it
sometimes work, you shouldn't compare strings with "==", but using
string functions, such as strcmp()... or similar_text(), etc.
This is PHP, not C. Operators such as == support strings for a
reason, people should use them as such.
You shouldn't rely on what other languages do, but the one you're
working with; PHP has no explicit data-types and manages strings as
PERL does. Just as you say there's a reason why "==" supports
strings, there's also a reason (or more) for strcmp() to exists --it's
just safer to use strcmp() instead of "==", e.g: 24 == "24/7"
Safer, yes. And it'd be even better to do 24 === "24/7", in which case
you don't need a function call, it's probably faster (I'd imagine that
comparing equality is faster than finding out HOW close it is like
strcmp does), and as I mentioned, easier to read.
The only possible values of strcmp() are: 1, 0 & -1. Hence, basically
both are doing the same, the difference would be the value they return,
one returns a boolean, and the other an integer --strcmp() doesn't
compare "HOW close it is" one string from the other, you might be
talking about levenshtein(), similar_text(), soundex(), etc.
As for the speed, it would be "===" (0.0007), "==" (0.0008) and lastly
strcmp() (0.0012) in a quick test with 1000 comparisons. So yes, an
operator is faster than a function call (kind of obvious), but my point
was to use strcmp() instead of any of the operator based solely on
experience with string comparisons, that was all, and I certainly don't
think that would be a bad advice, but I think that say something like
"use the operator, it's faster" it is a bad advice, since you're not
explaining how does it work (e.g. "automatic casting") which could led
to unexpected results, don't you think? Anyway, that's something that
you find only in "special cases".
If you need to ensure type, (so that 0 == "foo" doesn't return true),
then you can use ===.
Using a function call that does more than you need when there is an
operator to achieve the same goal is bad advice.
I think you haven't encounter a "special case" to make you
understand "==" does NOT have the same behaviour as strcmp() It's
just like the (stranger) case of the loop
for ( $c = 'a'; $c <= 'z'; $c ++ )
echo $c;
I didn't say that it had the same behaviour, only the same goal; finding
out if two strings are equal. strcmp does MORE than that, it also finds
out how CLOSE they are. You almost never need that information, in which
case you're wasting processing time with a function call that does
something that you don't need. Come on, face it, how many times have
done anything with strcmp's return value OTHER than checking that it's
zero? I bet the cases are fairly rare.
I already "talked" above about what strcmp() does. As for the cases
that I've used strcmp() to know if two strings are equal, *obviously*
they're more than those I've used strcmp() to see what string is
"bigger" than the other ("custom-sorting" is the only case I remember)
Not to mention the fact that it leads to harder to read code. Which
of these has a more readily apparent meaning?
if ( strcmp($foo,$bar) == 0 )
if ( $foo === $bar )
That might be true, either way you need to know the language to
understand what the first line does and that the second isn't a typo.
=== is a basic operator. One has to assume that somebody writing code is
at least familiar with the basic operators. If not, well, asking them to
know what the function strcmp does and what it means when it returns
zero is just as onerous. If not more so. And again, strcmp wastes time
calculating information we don't NEED.
"===" is not that of a basic operator, not even in PHP. And "==" looks
like a typo for those new to C (or similar), so they have to *learn*
what does it mean, the same goes for strcmp() --which may be even more
familiar than "===" for some people (me included)
--
Atentamente / Sincerely,
J. Rafael Salazar Magaña
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