Question

I have a form that uses inputs to create and array. The inputs are not all required but at least one is.

<form method="post" action="process.php">
    <input type="text" name="MAC[]" maxlength="12" />
    <input type="text" name="MAC[]" maxlength="12" />
    <input type="text" name="MAC[]" maxlength="12" />
    <input type="text" name="MAC[]" maxlength="12" />
    <input class="submitbg" type="submit" value="Register" name="submit"/>
 </form>

Now on process.php I want to loop through the array remove two types of special characters : ; then make all upper case, and verify there are only 12 characters and then serialize the arrray.

$my_array = $_POST['MAC'];
foreach ($my_array as $val){
    $val = strtoupper($val);
    $val = str_replace(";","",$val);
    $val = str_replace(":","",$val);
    $val = trim($val);
    if (strlen($val) != 12)){
        $valid = false;
        $error = "Your MAC address is not 12 characters long";
    }
}
$mac_addresses = serialize($my_array);

// if valid is not false do something with the cleaned up array.

The questions:

1. Will my foreach loop save the updated values back into the array?
2. How to check to make sure there is at least one array value?

Answer 1

1. What’s the question?
2. you can do str_replace(array(';',':'),'',$val);
3. It’s usually better to trim before doing other processing on the same variable due to the overhead involved in processing data you will eventually cut
4. Consider using break on errors, if you halt execution on one error.
5. You’re not really doing any updates to $my_array.

Consider doing:

foreach($my_array as &$val)

You pass by reference so all updates to $val happen to the actual array. Or:

foreach($my_array as $key=>$val){
    $my_array[$key]=trim($my_array[$key]);

You can also try to create a new array for your sanitized data and then over-write your old array. It all depends on needs.