Foreach: Get All The Keys That Have The Value "X" - php

Question

Suppose I have an array like this:
$array = array("a","b","c","d","a","a");
and I want to get all the keys that have the value "a".
I know I can get them using a while loop:
while ($a = current($array)) {
if ($a == 'a') {
echo key($array).',';
}
next($array);
}
How can I get them using a foreach loop instead?
I've tried:
foreach ($array as $a) {
if ($a == 'a') {
echo key($array).',';
}
}
and I got
1,1,1,
as the result.

Answer 1

If you would like all of the keys for a particular value, I would suggest using array_keys, using the optional search_value parameter.
$input = array("Foo" => "X", "Bar" => "X", "Fizz" => "O");
$result = array_keys( $input, "X" );
Where $result becomes
Array (
[0] => Foo
[1] => Bar
)
If you wish to use a foreach, you can iterate through each key/value set, adding the key to a new array collection when its value matches your search:
$array = array("a","b","c","d","a","a");
$keys = array();
foreach ( $array as $key => $value )
$value === "a" && array_push( $keys, $key );
Where $keys becomes
Array (
[0] => 0
[1] => 4
[2] => 5
)

Answer 2

You can use the below to print out keys with specific value
foreach ($array as $key=>$val) {
if ($val == 'a') {
echo $key." ";
}
}

Answer 3

here's a simpler filter.
$query = "a";
$result = array_keys(array_filter($array,
function($element)use($query){
if($element==$query) return true;
}
));

Answer 4

use
foreach($array as $key=>$val)
{
//access the $key as key.
}