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PHP array_fill_keys() function (with example)

Hey everyone,
I'm fairly new to PHP and I recently came across the array_fill_keys() function. I've been trying to understand how it works, but I'm a bit confused.

From what I gather, array_fill_keys() is used to create a new array with specified keys, and the same value for each key. However, I'm having trouble understanding how to use it in practice.

Could someone please provide me with a clear example of how to use the array_fill_keys() function? It would be greatly appreciated if you could explain the syntax and provide a simple code snippet to help me understand better.

Thanks in advance for your help!

All Replies


I totally get what you mean! array_fill_keys() can be a bit confusing at first, but once you get the hang of it, it becomes quite useful.

I remember when I first started using PHP, I had a project where I needed to create an array of days of the week as keys, and assign a default value of 'busy' to each day. Initially, I was manually creating each key-value pair, which was time-consuming and not efficient at all.

However, I stumbled upon array_fill_keys() and it turned out to be a lifesaver. It allowed me to easily generate the array I needed with just a single line of code.

Here's an example snippet that showcases how you can use array_fill_keys() to dynamically create an array:

// Desired keys
$daysOfWeek = ['Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday'];

// Default value
$defaultValue = 'busy';

// Generate the array using array_fill_keys()
$busyDays = array_fill_keys($daysOfWeek, $defaultValue);

// Let's see the result

When you execute this code, you'll get the following output:

array(5) {
string(4) "busy"
string(4) "busy"
string(4) "busy"
string(4) "busy"
string(4) "busy"

As you can see, the array_fill_keys() function created a new array where each day of the week is a key, and the value of each key is set to 'busy'.

I hope this personal example helps you grasp how array_fill_keys() can be used in practical scenarios. Don't hesitate to reach out if you have any further questions!


Hey there,
I totally understand where you're coming from! When I first encountered the array_fill_keys() function in PHP, I was a bit puzzled as well. But let me share my personal experience and how I ended up using it in a project.

So, I was working on a task management system where I needed to generate an array of task IDs for a specific project. Each task ID had a prefix related to the project, followed by a unique numerical value. Initially, I was manually creating each array element, but it became quite tedious and error-prone.

Thankfully, I stumbled upon the array_fill_keys() function, which turned out to be the perfect solution for my situation. It allowed me to dynamically create an array with the desired keys and assign a value to each key simultaneously.

Here's a brief code snippet to demonstrate how I used array_fill_keys() in my project:

// Project prefix
$projectPrefix = 'TASK';

// Total number of tasks
$totalTasks = 5;

// Generate task IDs using array_fill_keys()
$taskIDs = array_fill_keys(range(1, $totalTasks), $projectPrefix);

// Output the array

When you execute this code, it will generate an array like this:

[1] => TASK
[2] => TASK
[3] => TASK
[4] => TASK
[5] => TASK

In this example, array_fill_keys() created an array with keys ranging from 1 to the total number of tasks ($totalTasks). Each key was assigned the project prefix 'TASK'. This way, I was able to generate task IDs for the project effortlessly.

I hope sharing my personal experience helps you understand how array_fill_keys() can be applied practically. If you have any further questions or need more examples, feel free to ask!


Hey there!

I recently had a similar confusion with the array_fill_keys() function, so I can definitely help you out here.

Basically, array_fill_keys() allows you to create a new array by specifying the keys you want and the value you want for each key. It's quite handy when you need to initialize an array with a certain set of keys and values.

To give you a practical example, let's say you want to create an array called $fruits with three keys: 'apple', 'banana', and 'orange'. And you want each of these keys to have the value 'fruit'. Here's how to achieve that using array_fill_keys():

$keys = ['apple', 'banana', 'orange'];
$values = 'fruit';

$fruits = array_fill_keys($keys, $values);

When you run this code, you'll get the following output:

[apple] => fruit
[banana] => fruit
[orange] => fruit

So, as you can see, the array_fill_keys() function creates a new array with the specified keys and assigns the same value ('fruit' in this case) to each key.

I hope this example clears things up for you. Let me know if you have any further questions or need more examples!

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