Re: [PHP] Array mysteries
Read the manual again, especially the part about variable scope near
the beginning.
On Sun, March 11, 2007 3:51 am, Otto Wyss wrote:
I want to convert weekdays with a simple function like
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
function convert_from_weekday ($weekday) {
return $wdays[$weekday];
}
but this doesn't work while
$wdays[$weekday];
outside of the function works correct. Has anybody an idea where's my
mistake? I'd like to use a function so I may return substrings of the
weekday.
O. Wyss
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Re: [PHP] Array mysteries
On Sun, March 11, 2007 12:02 pm, Edward Vermillion wrote:
On Mar 11, 2007, at 10:02 AM, tedd wrote:
At 3:05 PM +0100 3/11/07, Tijnema ! wrote:
On 3/11/07, tedd mailto:[EMAIL PROTECTED][EMAIL PROTECTED]
wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date(l)
would also return the day of the month :)
Tijnema
It's the technique and not the specific data thing I was
addressing. When I'm confronted with a case condition, I typically
use the switch statement. But, your solution provided me with
another way to look at that.
Cheers,
tedd
But what's the cost of this in a loop, rebuilding the array each
time, as compared to a switch statement? Just another thought...
If you are calling this function a ridiculous number of times, you
could use a static variable.
function convert_from_weekday($weekday){
static $weeks = '';
if ($weeks === '') $weeks = array('Sonntag', 'Montag', ...);
}
It's kind of a shame that PHP won't let you just initialize a static
to an array, but there it is.
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Re: [PHP] Array mysteries
On Sun, March 11, 2007 2:57 pm, Edward Vermillion wrote: Would the array lookup be faster for a lesser-used option/key in a situation where there were quite a few options? (you wouldn't have to go through the whole switch to get to the option at the end (?) or would you? I have no idea how that all works internally) Almost for sure, a 'switch' is going to win over the array hash lookup in almost all cases, as the switch is built into the opcodes, and not an array hash lookup. If I understood a thread on Internals last month correctly, internally, the order of the case statements does matter, somewhat, but you *DO* have to be calling something a ZILLION times for it to matter in the real world. Stressing out over performance instead of maintainability is almost always the wrong way to start a project. You don't want to be a complete idiot, but often-times the performance bottle-neck ends up being somewhere entirely different from where you expected anyway. Write the code as straight-forward and maintainable as you can first. Then measure it for performance to see if it's acceptable. -- Some people have a gift link here. Know what I want? I want you to buy a CD from some starving artist. http://cdbaby.com/browse/from/lynch Yeah, I get a buck. So? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Array mysteries
On 3/11/07, Otto Wyss [EMAIL PROTECTED] wrote:
I want to convert weekdays with a simple function like
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
function convert_from_weekday ($weekday) {
return $wdays[$weekday];
}
but this doesn't work while
$wdays[$weekday];
outside of the function works correct. Has anybody an idea where's my
mistake? I'd like to use a function so I may return substrings of the
weekday.
O. Wyss
$wdays is not defined inside the function, so you can do a few things:
- Pass the $wdays inside the function:
function convert_from_weekday ($weekday,$wdays) {
return $wdays[$weekday];
}
$day = convert_from_weekday(0,$wdays) // $day = Sonntag
- You could define $wdays inside the function
function convert_from_weekday ($weekday,$wdays) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
- If you are working from inside a class, you could define $wdays as a
public variable.
I think this solved your problem, but don't hesitate to ask for more!
Tijnema
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Re: [PHP] Array mysteries
At 9:51 AM +0100 3/11/07, Otto Wyss wrote:
I want to convert weekdays with a simple function like
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
function convert_from_weekday ($weekday) {
return $wdays[$weekday];
}
but this doesn't work while
$wdays[$weekday];
outside of the function works correct. Has anybody an idea where's
my mistake? I'd like to use a function so I may return substrings of
the weekday.
If the above is your exact code, then the problem is one of scope;
move the $wdays declaration inside your convert_from_weekday()
function.
However, you may want to investigate the formatting functions of date():
http://php.he.net/manual/en/function.date.php
Date should return names using the native locale; if you want to
return date strings for other locales/languages, use setlocale() -
http://php.he.net/manual/en/function.setlocale.php
- and strftime() -
http://php.he.net/manual/en/function.strftime.php
I think you'll find your work has been at least partially done for
you. And, see
http://php.he.net/manual/en/language.variables.scope.php
for more information on variable scope.
steve
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Re: [PHP] Array mysteries
Steve Edberg wrote:
At 9:51 AM +0100 3/11/07, Otto Wyss wrote:
function convert_from_weekday ($weekday) {
return $wdays[$weekday];
}
If the above is your exact code, then the problem is one of scope;
move the $wdays declaration inside your convert_from_weekday()
function.
I'm more used to C++ than PHP, with global $wdays; it works.
However, you may want to investigate the formatting functions of date():
http://php.he.net/manual/en/function.date.php
Date should return names using the native locale; if you want to
return date strings for other locales/languages, use setlocale() -
http://php.he.net/manual/en/function.setlocale.php
Thanks, I'll keep this in mind.
O. Wyss
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Re: [PHP] Array mysteries
- Original Message -
From: Otto Wyss [EMAIL PROTECTED]
To: php-general@lists.php.net
Sent: Sunday, March 11, 2007 11:14 AM
Subject: Re: [PHP] Array mysteries
Steve Edberg wrote:
At 9:51 AM +0100 3/11/07, Otto Wyss wrote:
function convert_from_weekday ($weekday) {
return $wdays[$weekday];
}
If the above is your exact code, then the problem is one of scope; move
the $wdays declaration inside your convert_from_weekday() function.
I'm more used to C++ than PHP, with global $wdays; it works.
Unless you are using the array elsewhere, it might be a good idea to put it
inside the function so as to not polute the global namespace with variable
names that have no need to be there. In large applications, there is a
non-trivial chance that someone else might use a variable by the same name
and ruin your translation table. It will be slightly slower, though.
As for the localization functions, you might see their effect in:
http://www.satyam.com.ar/int/setlocale/index.php?locale=de_DEsubmit=Aceptar
the input box allows you to enter different locales, the previous URL
already has German selected.
Satyam
However, you may want to investigate the formatting functions of date():
http://php.he.net/manual/en/function.date.php
Date should return names using the native locale; if you want to return
date strings for other locales/languages, use setlocale() -
http://php.he.net/manual/en/function.setlocale.php
Thanks, I'll keep this in mind.
O. Wyss
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Re: [PHP] Array mysteries
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday,$wdays) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
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Re: [PHP] Array mysteries
On 3/11/07, tedd [EMAIL PROTECTED] wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date(l) would also
return the day of the month :)
Tijnema
--
---
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Re: [PHP] Array mysteries
At 3:05 PM +0100 3/11/07, Tijnema ! wrote:
On 3/11/07, tedd mailto:[EMAIL PROTECTED][EMAIL PROTECTED] wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date(l)
would also return the day of the month :)
Tijnema
It's the technique and not the specific data thing I was addressing.
When I'm confronted with a case condition, I typically use the switch
statement. But, your solution provided me with another way to look at
that.
Cheers,
tedd
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Re: [PHP] Array mysteries
On Mar 11, 2007, at 10:02 AM, tedd wrote:
At 3:05 PM +0100 3/11/07, Tijnema ! wrote:
On 3/11/07, tedd mailto:[EMAIL PROTECTED][EMAIL PROTECTED] wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date(l)
would also return the day of the month :)
Tijnema
It's the technique and not the specific data thing I was
addressing. When I'm confronted with a case condition, I typically
use the switch statement. But, your solution provided me with
another way to look at that.
Cheers,
tedd
But what's the cost of this in a loop, rebuilding the array each
time, as compared to a switch statement? Just another thought...
Ed
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Re: [PHP] Array mysteries
On Sunday 11 March 2007 12:02 pm, Edward Vermillion wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
*snip*
It's the technique and not the specific data thing I was
addressing. When I'm confronted with a case condition, I typically
use the switch statement. But, your solution provided me with
another way to look at that.
Cheers,
tedd
But what's the cost of this in a loop, rebuilding the array each
time, as compared to a switch statement? Just another thought...
Ed
That's why you can just declare it static:
function convert_from_weekday ($weekday) {
static $wdays = array(
0 = Sonntag,
1 = Montag,
2 = Dienstag,
3 = Mittwoch,
4 = Donnerstag,
5 = Freitag,
6 = Samstag
);
return $wdays[$weekday];
}
And then it's only ever defined once, and the lookup is just an array-key
search that happens down in the engine. I do this sort of mapping all the
time.
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exclusive property, it is the action of the thinking power called an idea,
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Re: [PHP] Array mysteries
At 12:02 PM -0500 3/11/07, Edward Vermillion wrote:
On Mar 11, 2007, at 10:02 AM, tedd wrote:
At 3:05 PM +0100 3/11/07, Tijnema ! wrote:
On 3/11/07, tedd mailto:[EMAIL PROTECTED][EMAIL PROTECTED] wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date(l)
would also return the day of the month :)
Tijnema
It's the technique and not the specific data thing I was
addressing. When I'm confronted with a case condition, I typically
use the switch statement. But, your solution provided me with
another way to look at that.
Cheers,
tedd
But what's the cost of this in a loop, rebuilding the array each
time, as compared to a switch statement? Just another thought...
Ed
It's just another way to look at a possible solution.
As for the cost, what are we talking about? I doubt that a typical
application would show any discernable difference in execution times.
One could test this easy enough by running both through 50k loops,
but even then I doubt that the times would be that much different --
but I may be wrong, been there before.
Cheers,
tedd
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Re: [PHP] Array mysteries
On Mar 11, 2007, at 1:59 PM, tedd wrote:
At 12:02 PM -0500 3/11/07, Edward Vermillion wrote:
On Mar 11, 2007, at 10:02 AM, tedd wrote:
At 3:05 PM +0100 3/11/07, Tijnema ! wrote:
On 3/11/07, tedd mailto:[EMAIL PROTECTED][EMAIL PROTECTED]
wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date
(l) would also return the day of the month :)
Tijnema
It's the technique and not the specific data thing I was
addressing. When I'm confronted with a case condition, I
typically use the switch statement. But, your solution provided
me with another way to look at that.
Cheers,
tedd
But what's the cost of this in a loop, rebuilding the array each
time, as compared to a switch statement? Just another thought...
Ed
It's just another way to look at a possible solution.
As for the cost, what are we talking about? I doubt that a
typical application would show any discernable difference in
execution times.
One could test this easy enough by running both through 50k loops,
but even then I doubt that the times would be that much different
-- but I may be wrong, been there before.
Cheers,
tedd
I don't know if there would be any difference either, which is why it
was a question.
Although Larry's suggestion of making the array static is something I
hadn't thought of.
Overall it is an interesting concept to use an array instead of a
switch, and I do wonder at what point, if any, that the two would
start to diverge resource-wise.
Would the array lookup be faster for a lesser-used option/key in a
situation where there were quite a few options? (you wouldn't have to
go through the whole switch to get to the option at the end (?) or
would you? I have no idea how that all works internally)
Ed
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Re: [PHP] Array mysteries
- Original Message -
From: Edward Vermillion [EMAIL PROTECTED]
To: tedd [EMAIL PROTECTED]
Cc: Tijnema ! [EMAIL PROTECTED]; php-general@lists.php.net
Sent: Sunday, March 11, 2007 8:57 PM
Subject: Re: [PHP] Array mysteries
On Mar 11, 2007, at 1:59 PM, tedd wrote:
At 12:02 PM -0500 3/11/07, Edward Vermillion wrote:
On Mar 11, 2007, at 10:02 AM, tedd wrote:
At 3:05 PM +0100 3/11/07, Tijnema ! wrote:
On 3/11/07, tedd mailto:[EMAIL PROTECTED][EMAIL PROTECTED] wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date (l)
would also return the day of the month :)
Tijnema
It's the technique and not the specific data thing I was addressing.
When I'm confronted with a case condition, I typically use the switch
statement. But, your solution provided me with another way to look at
that.
Cheers,
tedd
But what's the cost of this in a loop, rebuilding the array each time,
as compared to a switch statement? Just another thought...
Ed
It's just another way to look at a possible solution.
As for the cost, what are we talking about? I doubt that a typical
application would show any discernable difference in execution times.
One could test this easy enough by running both through 50k loops, but
even then I doubt that the times would be that much different -- but I
may be wrong, been there before.
Cheers,
tedd
I don't know if there would be any difference either, which is why it was
a question.
Although Larry's suggestion of making the array static is something I
hadn't thought of.
Overall it is an interesting concept to use an array instead of a switch,
and I do wonder at what point, if any, that the two would start to
diverge resource-wise.
Would the array lookup be faster for a lesser-used option/key in a
situation where there were quite a few options? (you wouldn't have to go
through the whole switch to get to the option at the end (?) or would
you? I have no idea how that all works internally)
Yes, you would. It goes sequentially through each case:. The array, on the
other hand, uses a hashing algorithm so it should be about even no matter
which option you pick.
Satyam
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Re: [PHP] Array mysteries
On 3/11/07, Satyam [EMAIL PROTECTED] wrote:
- Original Message -
From: Edward Vermillion [EMAIL PROTECTED]
To: tedd [EMAIL PROTECTED]
Cc: Tijnema ! [EMAIL PROTECTED]; php-general@lists.php.net
Sent: Sunday, March 11, 2007 8:57 PM
Subject: Re: [PHP] Array mysteries
On Mar 11, 2007, at 1:59 PM, tedd wrote:
At 12:02 PM -0500 3/11/07, Edward Vermillion wrote:
On Mar 11, 2007, at 10:02 AM, tedd wrote:
At 3:05 PM +0100 3/11/07, Tijnema ! wrote:
On 3/11/07, tedd mailto:[EMAIL PROTECTED][EMAIL PROTECTED]
wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date (l)
would also return the day of the month :)
Tijnema
It's the technique and not the specific data thing I was addressing.
When I'm confronted with a case condition, I typically use the
switch
statement. But, your solution provided me with another way to look
at
that.
Cheers,
tedd
But what's the cost of this in a loop, rebuilding the array
each time,
as compared to a switch statement? Just another thought...
Ed
It's just another way to look at a possible solution.
As for the cost, what are we talking about? I doubt that a typical
application would show any discernable difference in execution times.
One could test this easy enough by running both through 50k loops, but
even then I doubt that the times would be that much different -- but I
may be wrong, been there before.
Cheers,
tedd
I don't know if there would be any difference either, which is why
it was
a question.
Although Larry's suggestion of making the array static is something I
hadn't thought of.
Overall it is an interesting concept to use an array instead of
a switch,
and I do wonder at what point, if any, that the two would start to
diverge resource-wise.
Would the array lookup be faster for a lesser-used option/key in a
situation where there were quite a few options? (you wouldn't have
to go
through the whole switch to get to the option at the end (?) or would
you? I have no idea how that all works internally)
Yes, you would. It goes sequentially through each case:. The array, on
the
other hand, uses a hashing algorithm so it should be about even no matter
which option you pick.
Satyam
PHP is always fast, as long as you are not trying to do this 50k times, does
it make sense if a function takes 0.0056 or 0.0057 seconds to
execute?
I don't think so, so that means this is all going about users preference.
Tijnema
Re: [PHP] Array mysteries
On Sun, 2007-03-11 at 21:41 +0100, Satyam wrote:
- Original Message -
From: Edward Vermillion [EMAIL PROTECTED]
To: tedd [EMAIL PROTECTED]
Cc: Tijnema ! [EMAIL PROTECTED]; php-general@lists.php.net
Sent: Sunday, March 11, 2007 8:57 PM
Subject: Re: [PHP] Array mysteries
On Mar 11, 2007, at 1:59 PM, tedd wrote:
At 12:02 PM -0500 3/11/07, Edward Vermillion wrote:
On Mar 11, 2007, at 10:02 AM, tedd wrote:
At 3:05 PM +0100 3/11/07, Tijnema ! wrote:
On 3/11/07, tedd mailto:[EMAIL PROTECTED][EMAIL PROTECTED] wrote:
At 10:05 AM +0100 3/11/07, Tijnema ! wrote:
- You could define $wdays inside the function
function convert_from_weekday ($weekday) {
$wdays = array
(0 = Sonntag
,1 = Montag
,2 = Dienstag
,3 = Mittwoch
,4 = Donnerstag
,5 = Freitag
,6 = Samstag
);
return $wdays[$weekday];
}
$day = convert_from_weekday(0) // $day = Sonntag
Tijnema:
That's also a shorter version of a simple switch statement.
I haven't thought of, or seen, that before -- thanks.
tedd
Yeah it is, but i just used moved his $wdays inside the function...
but well, there are ofcourse a lot of other options, as date (l)
would also return the day of the month :)
Tijnema
It's the technique and not the specific data thing I was addressing.
When I'm confronted with a case condition, I typically use the switch
statement. But, your solution provided me with another way to look at
that.
Cheers,
tedd
But what's the cost of this in a loop, rebuilding the array each time,
as compared to a switch statement? Just another thought...
Ed
It's just another way to look at a possible solution.
As for the cost, what are we talking about? I doubt that a typical
application would show any discernable difference in execution times.
One could test this easy enough by running both through 50k loops, but
even then I doubt that the times would be that much different -- but I
may be wrong, been there before.
Cheers,
tedd
I don't know if there would be any difference either, which is why it was
a question.
Although Larry's suggestion of making the array static is something I
hadn't thought of.
Overall it is an interesting concept to use an array instead of a switch,
and I do wonder at what point, if any, that the two would start to
diverge resource-wise.
Would the array lookup be faster for a lesser-used option/key in a
situation where there were quite a few options? (you wouldn't have to go
through the whole switch to get to the option at the end (?) or would
you? I have no idea how that all works internally)
Yes, you would. It goes sequentially through each case:. The array, on the
other hand, uses a hashing algorithm so it should be about even no matter
which option you pick.
Not quite. When the number of possible keys are small, a rote traversal
using language constructs such as if/elseif/else/case is likely to be
faster than incurring the overhead of the hash search. However, in
general the hash search will be faster. Having said that, the use of an
array to hold the key/value pairs produces a very succinct and readable
solution. Additionally, retrieval of such values from the database is
more easily implemented using the array methodology. For those not aware
of using static hash lookups with database results I've included an
example:
?php
function convert_from_weekday( $weekday )
{
static $days = null;
if( $days === null )
{
$query =
SELECT
weekday_id
weekday_name
FROM
weekday_table ;
$days = array();
if( $db-query( $query ) )
{
while( $db-nextRow() )
{
$days[$db-getField( 'weekday_id' )] =
$days[$db-getField( 'weekday_name' )];
}
}
}
if( isset( $days[$weekday] ) )
{
return $days[$weekday];
}
return null;
}
?
Cheers,
Rob.
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