print_r()

print_r() is a built-in PHP function used for displaying the contents of an array or an object in a human-readable format. It’s particularly helpful for debugging and understanding the structure of complex data structures in your PHP code. When you use print_r, it prints the array or object’s values and structure to the browser or the console.

<?php

$a = 1;

print_r($a);
/*
Array
(
    [0] => 1
)
*/

?>

Documentation

Related : Assertions, Echo, Print, var_dump()