array_unique
    (PHP 4 >= 4.0.1, PHP 5)
array_unique -- Removes duplicate values from an array
Description
array 
array_unique ( array array )
     array_unique() takes input
     array and returns a new array
     without duplicate values.
    
     Note that keys are preserved. array_unique() sorts
     the values treated as string at first, then will keep the first key
     encountered for every value, and ignore all following keys. It does not
     mean that the key of the first related value from the unsorted
     array will be kept.
    
Note: 
      Two elements are considered equal if and only if
      (string) $elem1 === (string) $elem2. In words:
      when the string representation is the same.
     
      The first element will be used.
     
     
Example 1. array_unique() example 
<?php $input = array("a" => "green", "red", "b" => "green", "blue", "red"); $result = array_unique($input); print_r($result); ?>
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 The above example will output: 
Array (     [a] => green     [0] => red     [1] => blue )
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Example 2. array_unique() and types 
<?php $input = array(4, "4", "3", 4, 3, "3"); $result = array_unique($input); var_dump($result); ?>
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 The above example will output: 
array(2) {   [0] => int(4)   [2] => string(1) "3" }
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