Combining Parallel Arrays (in PHP)

Needed a free photo for this coding post, and Pexels showed me this. This photo wins.

I was today years old when I discovered you can pass multiple arrays to PHP’s array_map() function. 😶

For example, lets say you have two parallel arrays: $firstNames and $lastNames.

You can use array_map() to combine them into a single array of $fullNames. Here’s how:

$firstNames = [“Alice”, “Bob”, “Clarence”];
$lastNames = [“Albinia”, “Barker”, “Cannon”];

$fullNames = array_map(function () {
    return “$firstName $lastName”;
}, $firstNames, $lastNames);

As a bonus, you can also pass additional variables with “use”:

$intro = “Hello, my name is”;
$greetings = array_map(function ($firstName, $lastName) use ($intro){
    return “$intro $firstName $lastName”;
}, $firstNames, $lastNames);

// Hello, my name is Alice Albinia
// Hello, my name is Bob Barker
// Hello, my name is Clarence Cannon

Need indexes? Our array_map() function can also be implemented to work like a for loop by passing array_keys() as the last argument:

$greetings = array_map(function ($firstName, $lastName, $i) use ($intro){
    return “($i) $intro $firstName $lastName”;
}, $firstNames, $lastNames, array_keys($firstNames));

// (1) Hello, my name is Alice Albinia
// (2) Hello, my name is Bob Barker
// (3) Hello, my name is Clarence Cannon

Hope someone finds this useful! I just found it funny how I use this function almost daily and never realized it took multiple arguments. 😎