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What is the print_r() function in PHP?

NDUKWE CHIDERA K.

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

Overview

In PHP, if you want to output anything to the output screen, the most common functions to use are the echo and print functions.

Apart from echo and print, there are a couple of other functions we can use to do any kind of printing to screen, including the print_r() function.

The print_r() function

The print_r() function is part of the PHP standard library and displays information about a variable in a form that can easily be read by humans.

With the print_r() function, the information contained in complex variables (such as arrays and objects) is stripped out to the users in a simple, comprehensible format.

Syntax


print_r($value,$return);

Parameters

The print_r() function requires two parameters:

  1. $value: the variable whose value is to be output to the screen.

  2. $return: can be set as true or false. By default, this parameter is false. If set to true, the print_r() function will not print the information to screen. The value of the variable will be returned which you can capture and use for further actions.

Return value

When a string, int, or float is passed as the $value parameter, the value of the variable itself will be printed.

If it is an array, the array values will be printed in a key-value pair format. This also happens to the object variable.


Just like var_dump() and var_export(), print_r() will show protected and private properties of objects.

Code

Below is an example of how to use the print_r() function:

<?php
$a1 = array ("fruit" =>["apples", "oranges", "pears"]);
$a2 = 'This is a string';
$a3 = 5.6;
//$array = array_push(array ("fruit" => $a1, "vegies" => $a2, "money" => $a3));
print_r($a1);
print_r($a2);
//let use print_r to return a value and save it
$ar3ref = print_r($a3, true);
//use echo to print to output the returned value
echo "\n".$ar3ref;
?>

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php
communitycreator

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

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