array_key_exist() with array as key

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.

The function you are looking for is array_intersect(). Both your arrays are indexed with sequential numbers starting from 0, their keys are not interesting. — axiac
– axiac, Commented Jun 22, 2016 at 12:15

Sara Fuerst · Accepted Answer · 2016-06-22 12:15:19Z

4

You can use the array_intersect function:

$overlap = array_intersect($voucher, $voucher_presenti);

You can find more examples in the documentation.

answered Jun 22, 2016 at 12:15

Sara Fuerst

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1 Comment

Peter Over a year ago

Didn't know that function. Nice and clean answer. :)

Peter · Accepted Answer · 2016-06-22 12:23:04Z

1

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

answered Jun 22, 2016 at 12:23

Peter

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Comments

Cobuz Alexandru · Accepted Answer · 2016-06-22 12:31:45Z

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. */

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