the usort 's puzzle

[youngord]

<?php
$mix=array(
array("A",10),
array("B",5),
array("C",100)
);
function com($x,$y){
echo $x[0];
}
usort($mix,'com');
?>

i think the $x[0] result is A,
but the final $x[0] result is BC.
why???

[Michael Fesser]

..oO(yo******@gmail.com)

><?php
$mix=array(
array("A",10),
array("B",5),
array("C",100)
);
function com($x,$y){
echo $x[0];
}
usort($mix,'com');
?>

i think the $x[0] result is A,
but the final $x[0] result is BC.
why???

What are you trying to do? The above doesn't really makes sense.
The result depends on what sorting algorithm PHP uses internally.

Micha

[Shelly]

<yo******@gmail.comwrote in message
news:11**********************@g4g2000hsf.googlegro ups.com...

<?php
$mix=array(
array("A",10),
array("B",5),
array("C",100)
);
function com($x,$y){
echo $x[0];
}
usort($mix,'com');
?>

i think the $x[0] result is A,
but the final $x[0] result is BC.
why???

From www.php.net:
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.

So, what does "com" return?

Shelly

[Rik Wasmus]

On Sun, 30 Sep 2007 05:37:16 +0200, <yo******@gmail.comwrote:

<?php
$mix=array(
array("A",10),
array("B",5),
array("C",100)
);
function com($x,$y){
echo $x[0];
}
usort($mix,'com');
?>

i think the $x[0] result is A,
but the final $x[0] result is BC.
why???

Because PHP uses an internal construct to sort, starting whereever it's
internal functionality is written to start, which should not matter. If it
compares (B,A) & (C,B), it knows enough to sort.
--
Rik Wasmus