Remove duplicated values function - php

Question

function remove_values($arr){
$_a = array();
while(list($key,$val) = each($arr)){
$_a[$val] = 1;
}
return array_keys($_a);
}
i can't follow the above function well.i don't know what's the effect of $_a[$val] = 1; anyone can explain it to me thank you

Answer 1

For the purpose of the function, Why not just use array_unique($array)?
Like this
function remove_values($arr){
return array_keys(array_unique($arr));
}
Update:
Ok, Since you are trying to learn. Here is the explanation for the function in the post
function remove_values($arr){
$_a = array(); //Creates a temporary array to store matching
while(list($key,$val) = each($arr)){ //till their is item is array, loop it
$_a[$val] = 1; //Store in the temporary array with array's values as index, thus eliminating the duplicates
//^ Here storing with the value as index IS THE KEY
}
return array_keys($_a); //return only the keys, which in fact are the unique values
}

Answer 2

Well all this does is to insert the value into the key of an array. Since all keys are unique in an array, you will remove all duplicates.
array_keys() simply gives back that array in it's ordinary form.
Example:
$arr = array('red', 'green', 'red');
$arr = remove_values($arr);
gives
array( 'red' => 1,
'green' => 1);
which results in
array('red', 'green');
since "red" can only be a keyvalue once.

Answer 3

Very nice function actually.
$_a[$val] = 1;
makes every element to be signed once, so returned once meaning that duplicates are removed. Than the array_keys($_a) function rebuilds and sorts the array. I liked it.

Answer 4

its assign the value 1 to value part. for ex:
<?php
function remove_values($arr){
$_a = array();
while(list($key,$val) = each($arr)){
$_a[$val] = 1;
}
print_r($_a);
return array_keys($_a);
}
$arr = array('a' => 'apple', 'b' => 'banana', 'c' => 'cranberry');
$sed = remove_values($arr);
print_r($sed);
?>
It return two array values:
Array
(
[apple] => 1
[banana] => 1
[cranberry] => 1
)
Array
(
[0] => apple
[1] => banana
[2] => cranberry
)
Now tis easy for you to understand the effect of value '1'.