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PHP

Filters elements of an array using a callback function


array_filter

(PHP 4 >= 4.0.6, PHP 5)

array_filterFilters elements of an array using a callback function

Description

array array_filter ( array $input [, callable $callback = "" ] )

Iterates over each value in the input array passing them to the callback function. If the callback function returns true, the current value from input is returned into the result array. Array keys are preserved.

Parameters

input

The array to iterate over

callback

The callback function to use

If no callback is supplied, all entries of input equal to FALSE (see converting to boolean) will be removed.

Return Values

Returns the filtered array.

Examples

Example #1 array_filter() example

<?php
function odd($var)
{
    
// returns whether the input integer is odd
    
return($var 1);
}

function 
even($var)
{
    
// returns whether the input integer is even
    
return(!($var 1));
}

$array1 = array("a"=>1"b"=>2"c"=>3"d"=>4"e"=>5);
$array2 = array(6789101112);

echo 
"Odd :\n";
print_r(array_filter($array1"odd"));
echo 
"Even:\n";
print_r(array_filter($array2"even"));
?>

The above example will output:

 Odd : Array (  [a] => 1  [c] => 3  [e] => 5 ) Even: Array (  [0] => 6  [2] => 8  [4] => 10  [6] => 12 ) 

Example #2 array_filter() without callback

<?php

$entry 
= array(
             
=> 'foo',
             
=> false,
             
=> -1,
             
=> null,
             
=> ''
          
);

print_r(array_filter($entry));
?>

The above example will output:

 Array (  [0] => foo  [2] => -1 ) 

Notes

Caution

If the array is changed from the callback function (e.g. element added, deleted or unset) the behavior of this function is undefined.

See Also

  • array_map() - Applies the callback to the elements of the given arrays
  • array_reduce() - Iteratively reduce the array to a single value using a callback function
  • array_walk() - Apply a user function to every member of an array



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