PHP write array to a file. With code examples

To write a PHP array to a file, you need to call the file_put_contents() function in combination with the print_r() or var_export() function.

Let’s see an example of how to write PHP array to a file.

Suppose you have an array as follows:

<?php

$user = array (
    "name" => "Nathan", 
    "age" => "29", 
    "skills" => array ("JavaScript", "PHP", "Python")
);

You can print the $user above with the following code:

file_put_contents("output.txt", print_r($user, true));

In the above code, the file_put_contents() function look for a file named output.txt. When output.txt isn’t found, the function will create one.

The print_r() function is used for printing information about a variable in a human-readable format.

With the second parameter set to true, the function will return the output instead of printing it.

Because of that, the print_r() output will be written to the output.txt file.

Here’s the content of the output.txt file:

Array
(
    [name] => Nathan
    [age] => 29
    [skills] => Array
        (
            [0] => JavaScript
            [1] => PHP
            [2] => Python
        )

)

You can also use the var_export() function as an alternative to the print_r() function like this:

<?php

$user = array (
    "name" => "Nathan", 
    "age" => "29", 
    "skills" => array ("JavaScript", "PHP", "Python"));

file_put_contents("output.txt", var_export($user, true));

The var_export() function will print the array in a slightly different format as shown below:

array (
  'name' => 'Nathan',
  'age' => '29',
  'skills' => 
  array (
    0 => 'JavaScript',
    1 => 'PHP',
    2 => 'Python',
  ),
)

Personally, I think the print_r() function is more readable than var_export(). But you’re free to use one of them in your code.

Finally, you can also add the FILE_APPEND flag to the file_put_contents() function to make it append the output instead of overwriting it.

By default, file_put_contents() overwrite any text written in your file. Adding the FILE_APPEND flag will make it append the text instead.

Suppose you write two arrays to the output.txt file as follows:

$user = array (
    "name" => "Nathan", 
    "age" => "29", 
    "skills" => array ("JavaScript", "PHP", "Python"));

file_put_contents("output.txt", print_r($user, true));

$user = array (
    "name" => "Jane", 
    "age" => "24", 
    "skills" => array ("HTML", "CSS"));

file_put_contents("output.txt", print_r($user, true), FILE_APPEND);

The output in the text file is as follows:

Array
(
    [name] => Nathan
    [age] => 29
    [skills] => Array
        (
            [0] => JavaScript
            [1] => PHP
            [2] => Python
        )

)
Array
(
    [name] => Jane
    [age] => 24
    [skills] => Array
        (
            [0] => HTML
            [1] => CSS
        )

)

Without the FILE_APPEND flag, the first array will be overwritten.

Now you’ve learned how to write PHP array to a file. Nice work! 👍

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