Join strings and separate with a comma using PHP [duplicate]

Question

Using PHP, I would like to select certain values from an array of objects, join them to form one continuous string separated by commas, and save this to a variable named $isbn.

I have an array of objects named $items. A var_dump($items) produces this. I need to select the item_isbn value.

My desired result is;

echo $isbn

// would produce
// '0-7515-3831-0,978-0-141-38206-7,978-1-30534-114-1'

Getting rid of the hyphens would be a bonus but I think I can achieve this using str_replace.

Answer 1

Here we go:

$isbnList = [];
foreach ($arrayObject as $item) {
    if (isset($item->item_isbn)) {
        $isbnList[] = $item->item_isbn;
    }
}

$isbn = implode(",", $isbnList);

Check it:

echo $isbn;

For your information:

• The foreach works because it's an array. It doesn't care each of the item inside it.
• Each of the object ($item) in the loop is the default object of php (as the dump data you provided). Which is supposed to be called as $object->property. This object's property are not sure to always available, so checking whether it's available by php built-in function names isset() is essential.
• By knowing implode() is built-in function from php to build a string with separator base on an one side array (means each of item in this one side array must be a scalar value (int, string)). We build this array to ready for the call.
• The rest is just about syntax to how-to work with array or object... You can easily lookup on php manual page, eg: http://php.net/manual/en/language.types.array.php

Most popular programming languages nowadays provide us built-in function like this implode(), just different naming.