将复选框数组分配给变量

I am trying to use a checkbox to populate a single string in a database with specific formatting. I can successfully print the array, but I don't understand how to assign this to a variable in order to connect to the database and to use again elsewhere on the site. Here is the html:

 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="C">Commercials
 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="CP">Commercial Print
 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="V">Voice Overs
 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="X">Background Work
 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="F">Film
 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="TV">Television
 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="BT">Business Theatre Industrials
 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="I">Film Industrials
 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="MV">Music Videos

PHP:

foreach($_POST['bookCodes'] as $codes) {
    print "(".$codes.")";
};

I want the printed string to equal $bookCodes. I have tried putting the array in a function but then I get the first value only. Here is that code:

function prepBookCodes ($value)
{
    if (isset($_POST[$value])) {
        foreach ($_POST[$value] as $codes) {
            return "(" . $codes . ")";
        }
    }
}
$bookCodes = prepBookCodes('bookCodes');

print $bookCodes;

Any help would be greatly appreciated!

Concatenation is the answer. Make your function return something please!

function prepBookCodes ($value)
{
    if (isset($_POST[$value])) {
        foreach ($_POST[$value] as $codes) {
            $string .= "(" . $codes . ")";
        }
    }

    return $string;
}
$bookCodes = prepBookCodes('bookCodes');

Your first declaration doesn't have it as an array:

<input type="checkbox" id="bookCodes" name="bookCodes" value="C">Commercials

Should be

 <input type="checkbox" id="bookCodes" name="bookCodes[]" value="C">Commercials

function prepBookCodes ($value)
{
    if (isset($_POST[$value])) {
        foreach ($_POST[$value] as $codes) {
           echo "(" . $codes . ")";
        }
    }
}

Maybe you can concatenate the post values into a single variable $bookCodes:

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    if (isset($_POST['bookCodes'])) {
        $bookCodes = '';
        foreach ($_POST['bookCodes'] as $codes) {
            $bookCodes .= "(" . $codes . ")";
        }
        print $bookCodes;
    }
}

If you for example check all the checkboxes, the $bookCodes variable will contain:

(C)(CP)(V)(X)(F)(TV)(BT)(I)(MV)