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Manual: array_flip
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array_flip

(PHP4 >= 4.0b4)

array_flip -- 配列の値を逆順にする

説明

array array_flip (array trans)

array_flip() は、配列を逆順にして返します。

例 1. array_flip()の例


$trans = array_flip ($trans);
$original = strtr ($str, $trans);

注意: この関数は、PHP 4.0で追加されました。


User Contributed Notes: array_flip

rlynch@ignitionstate.com
27-Jan-2000 12:53
'flip' may be very specific to a Perl hacker or something, but to us mere mortals this is an undefined term...
PHP4.0b3 doesn't have it yet, so I can't find out what it does easily and post it here. Sorry.
I thought it would be 'reverse', but there's an array_reverse, so...
Guess: Flip all the keys/values? What if the value isn't a valid key?



vwagner@tetondata.com
28-Feb-2000 01:58
I concur with the above. What the heck is "flip" order???

rasmus@php.net
16-Mar-2000 07:37
eg. $a[0]="abc"; $a[1]="def";
After an array_flip() you get:
$a["abc"]=0; $a["def"]=1;



tworks@troutworks.com
17-May-2000 02:06
One hackish but slick use of array_flip() is to reduce an array to only its unique values. An example:

<PRE>
&lt;?php
$a[0] = "Tom";
$a[1] = "Tom";
$a[2] = "Dick";
$a[3] = "Dick";
$a[4] = "Harry";
$trans = array_flip($a);
$a = array_flip($trans);
?>
</PRE>

Since array offsets must be unique, duplicates will be blown away. Is that too ugly?



monte@ispi.net
17-May-2000 11:57
Maybe a more appropriate name would be array_transpose. Think of it as a matrix.

monte@ispi.net
18-May-2000 12:01
Question: what if the values are arrays themselves? Then what happens when you "flip"?

jmayer@cobalt.com
13-Jul-2000 09:08
To uniquify a list, this is better
<pre>
$hash = array_flip($array);
$array = array_keys($hash);
</pre>
Otherwise: If you just do two array_flip operations, you end up with a sparse array (the elements in the old arrays that were duplicates are left as gaps).

 About Notes

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