array_key_exist() with array as key - php

Question

I'm trying to check if in an array there is any value of another array. The function array_key_exist() looks like what I'm searching for, but I don't understand how to give the key value at the function as an array. Here's the code:
$risultato_query_controllo_numero = mysql_query($query_controllo_numero);
$voucher_esistenti = array();
while(($row = mysql_fetch_assoc($risultato_query_controllo_numero))) {
$voucher_esistenti[] = $row['numero'];
}
Which populates the first array with numbers:
$voucher = range($numero, $numero + $quantita);
Which populates the second array with numbers.
What I need to do now is to check if any of the value in $voucher is present in $voucher_presenti.

Answer 1

You can use the array_intersect function:
$overlap = array_intersect($voucher, $voucher_presenti);
You can find more examples in the documentation.

Answer 2

You could use the in_array() function to get the result you are looking for.
$arrayOne = range(1, 10);
$arrayTwo = range(5, 15);
foreach ($arrayOne as $value) {
if (in_array($value, $arrayTwo)) {
echo 'value '.$value.' is in the first and second array.<br />';
}
}
Resources
in_array() - Manual

Answer 3

in_array could be a good solution for your need, for example you can assign $voucher_esistenti only when you have a new value in the sql row.
$risultato_query_controllo_numero=mysql_query($query_controllo_numero);
$voucher_esistenti=array();
while(($row = mysql_fetch_assoc($risultato_query_controllo_numero))){
if(!in_array($row['numero'], $voucher_esistenti) {
$voucher_esistenti[] = $row['numero'];
}
} // this solution isn't optimal, because you will check subarrays with each new value
There's a better way to achieve that, by using a hashmap which has a complexity of O(1) ( best complexity :) )
$risultato_query_controllo_numero=mysql_query($query_controllo_numero);
$voucher_esistenti=array();
while(($row = mysql_fetch_assoc($risultato_query_controllo_numero))){
// here is what we changed, instead of key = value, we actually append keys
if(!isset($voucher_esistenti[$row['numero']]) {
$voucher_esistenti[$row['numero']] = true;
}
}
/*
The second implementation is a lot faster due to the algorithm, but you will have to change the reading of $voucher_esistenti array. */