PHP function array_flip() used to reverse/exchange the key names in the array and the corresponding associated key values

Example

Reverse the key names in the array and the corresponding associated key values:

<?php
$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$result=array_flip($a1);
print_r($result);
?>

Definition and usage

array_flip() function is used to reverse/exchange arrays The key name in and the corresponding associated key value.

Syntax

array_flip(array);

Parameters	Description
array	Required. Specifies the array whose key/value pairs need to be reversed.

Technical details

Return value:	If the inversion is successful, the inversion is returned the array after. If the reversal fails, NULL is returned.
PHP version:	4+

## Note that the value in trans needs to be a legal key name , for example, it needs to be

integer or string. A warning will be emitted if the value is of the wrong type, and the key/value pair in question will not be reversed. If the same value appears multiple times, the last key name will be used as its value, and all
others will be lost. 　array_flip() returns FALSE if it fails.
Example:

$hills=array("first"=>"data1″,"second"=>"data2″,"third"=>"data1″); 
　　$hills=array_flip($hills); //还原键名 
　　$hills1=array_flip(array_flip($hills));//删除重复 
　　display $hills1

The result is:

data2 data1 two data.

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