ordering array echo

BEFOR

Not having much luck finding this answer, I come here.

Is there a way to order this echo other that by the first character?

I'm trying to find 2-3 ways to order this, rather than 1st letter alphabetically:

$region = array("Midwest", "Northeast", "Southeast", "Southwest", "Northwest");

NogDog

I'm sure there's a way (if nothing else by using the [man]usort/man function and a custom comparison function), but without knowing how you want it to sort it's hard to give any specifics.

BEFOR

to sort by the second or third character would be nice
( I'm assuming I can use with zip codes as well)

NogDog

usort($region, create_function('$a, $b', 'strcmp(substr($a, 1), substr($b, 1));'));

BEFOR

Okay, sorry this took so long but hre's what I have:

$i='0';  

$region = array("Midwest", "Northeast", "Southeast", "Southwest", "Northwest", "NonContig" );
usort($region, create_function('$a, $b', 'strcmp(substr($a, 1), substr($b, 1));'));  

foreach ($region as $foo) { 
echo $foo; 
if ($i !== count($array)) { 
echo ", "; // add comma space 
} 
$i++;  }

a) I believe there my have been some confusion -- what I wanted was to sort two seperate ways -- once by the second character and once by the third character. Unless I'm missing it here.

b) shouldn't the last value echoed appear without a trailing comma written this way?

c) I'm trying to hold as much of this as I can in an includes file (along with many different region arrays) to be echoed on another page. Yet it seems to be a single continuous statement. How can this be done?

laserlight

what I wanted was to sort two seperate ways -- once by the second character and once by the third character.

NogDog's example sorts according to the substring excluding the first character. If you literally want to sort according to the character (and only that character, in each sort), you would use:

$region = array("Midwest", "Northeast", "Southeast", "Southwest", "Northwest", "NonContig");
usort($region, create_function('$a, $b', 'strcmp($a[1], $b[1]);'));

Note that sorting $region on a subsequent sort with say, the third character instead, might result in a different sequence from sorting by the third character on the original unordered array. As such, you may need to keep a copy of the original unordered sequence.

b) shouldn't the last value echoed appear without a trailing comma written this way?

Yes. You can use an alternative that does what you want:

echo implode(', ', $region);

c) I'm trying to hold as much of this as I can in an includes file (along with many different region arrays) to be echoed on another page. Yet it seems to be a single continuous statement. How can this be done?

Use a two dimensional array?

BEFOR

note

my lastest version 09:28 PM DOES echoe a comma after the final value, but it shouldn't.

But your alternate works fine.

usort($region, create_function('$a, $b', 'strcmp($a[1], $b[1]);'));

//sort according to the character (and only that character, in each sort)

is giving me the exact same results as:

usort($region, create_function('$a, $b', 'strcmp(substr($a, 1), substr($b, 1));'));

// sorts according to the substring excluding the first character

with Midwest last in both cases, which shouldn't happen, since M comes before N

Use a two dimensional array?

I have no idea what this would look like. Are you talking about creaing two seperate arrays within the same region field and calling each by 'name' on a seperate page?

laserlight

with Midwest last in both cases, which shouldn't happen, since M comes before N

Actually, M and N does not matter. What matters is the second character. However, Midwest should still come first, since i is before o. I tested with:

<?php
$region = array("Midwest", "Northeast", "Southeast", "Southwest", "Northwest", "NonContig");
usort($region, create_function('$a, $b', 'strcmp($a[1], $b[1]);'));
echo implode(', ', $region);
?>

The result was incorrect:
Northwest, NonContig, Southwest, Southeast, Northeast, Midwest

Then I tested with:

<?php
function cmp($a, $b) {
    return strcmp($a[1], $b[1]);
}

$region = array("Midwest", "Northeast", "Southeast", "Southwest", "Northwest", "NonContig");
usort($region, 'cmp');
echo implode(', ', $region);
?>

The result was now correct:
Midwest, NonContig, Northwest, Southeast, Northeast, Southwest

Either both NogDog and I are doing something wrong, or we have just discovered a bug with PHP 5.2.1's version of create_function().

NogDog

I think the problem is we forgot to return something in create_function():

usort($region, create_function('$a, $b', 'return strcmp($a[1], $b[1]);'));

laserlight

Ah, yes. I automatically corrected it when I wrote the function from scratch, heh.

BEFOR

basic question:

function cmp($a, $b) { 
    return strcmp($a[1], $b[1]);

Gives: 'Midwest, NonContig, Northwest, Southeast, Northeast, Southwest '

I'm trying to interpret this. // suprised I haven't been able to find info on searches

the a, b represnet character orders?

yet when I substitite:

function cmp($a, $b) { 
    return strcmp($a[4], $b[1]);

Gives: ' Northwest, NonContig, Southwest, Southeast, Northeast, Midwest '

starting by the fourth character?

what's right in front of me that I cannot see?

laserlight

the a, b represnet character orders?

No, they are the array elements to be compared. The function in question is a comparator that returns a negative number if the first element is less than the second, 0 if the elements are equal, and a positive number if the first element is greater than the second.

If you want to compare the fifth character, you have to change the index of both $a and $b.

BEFOR

I'm sorry but you've totally lost me.

The function in question is a comparator that returns a negative number if the first element is less than the second

First element of what? the first element of all values contained within the given array?

Lets forget the 'fifth element'

For example, in the original array please tell me what it will compare:

$region = array("Midwest", "Northeast", "Southeast", "Southwest", "Northwest");

- I'm hoping this same applies to numeric values!

laserlight

Have you read the PHP manual concerning [man]usort/man?

BEFOR

why the problems logging in to make posts?
After I supply username and password I get " thank you for logging in, echoing my username, but then it keeps directing back to the log on page VBulletin?

.......................................................................................................................
I have reveiwed the documentation, seeing no real explanation of $a and $b

only:

When sorting a multi-dimensional array, $a and $b contain references to the first index of the array.

Elements -- what are you referring to laserlight?

laserlight

why the problems logging in to make posts?
After I supply username and password I get " thank you for logging in, echoing my username, but then it keeps directing back to the log on page VBulletin?

hmm... no problem for me, I was not logged out of PHP Builder at all.

I have reveiwed the documentation, seeing no real explanation of $a and $b

Ah, that is because $a and $b are placeholders, dummy variables. usort() is a sort function that takes a user supplied function as its comparator. This allows you to sort arrays in ways not directly anticipated by PHP's API (e.g., sorting in reverse order, for which there is rsort(), is anticipated).

Elements -- what are you referring to laserlight?

Now, since we have to supply a function as a comparator for usort() to work, we need to write a function that takes two elements of the array that is to be sorted. As stated in the PHP Manual: "The comparison function must return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second."

NogDog chose to name the first argument $a and the second argument $b. You could just as easily use $x and $y, $first and $second, etc.

bradgrafelman

BEFOR wrote:
why the problems logging in to make posts?
After I supply username and password I get " thank you for logging in, echoing my username, but then it keeps directing back to the log on page VBulletin?

Sounds like a browser cache issue - try hitting F5 (or shift/control+F5, whichever keystroke forces a hard refresh) if you log in but it redirects you to a login form again.