PHP | print_r() Function

The print_r() function is a built-in function in PHP and is used to print or display information stored in a variable. Syntax:

print_r( $variable, $isStore )

Parameters: This function accepts two parameters as shown in above syntax and described below.

1. $variable: This parameter specifies the variable to be printed and is a mandatory parameter.
2. $isStore: This an option parameter. This parameter is of boolean type whose default value is FALSE and is used to store the output of the print_r() function in a variable rather than printing it. If this parameter is set to TRUE then the print_r() function will return the output which it is supposed to print.

Return Value: If the $variable is an integer or a float or a string the function prints the value of the variable. If the variable is an array the function prints the array in a format which displays the keys as well as values, a similar notation is used for objects. If the parameter $isStore is set to TRUE then the print_r() function will return a string containing the information which it is supposed to print. Below programs illustrate the print_r() function: Program 1: PHP

<?php

// PHP program to illustrate
// the print_r() function

// string variable
$var1 = "Welcome to GeeksforGeeks";

// integer variable
$var2 = 101;

// array variable
$arr = array('0' => "Welcome", '1' => "to", '2' => "GeeksforGeeks");

// printing the variables
print_r($var1);
echo"\n";
print_r($var2);
echo"\n";
print_r($arr);

?>

Output:

Welcome to GeeksforGeeks
101
Array
(
    [0] => Welcome
    [1] => to
    [2] => GeeksforGeeks
)

Program 2: PHP

<?php

// PHP program to illustrate the print_r()
// function when $isStore is set to true

// array variable
$arr = array('0' => "Welcome", '1' => "to",
                     '2' => "GeeksforGeeks");
                     
// storing output of print_r() function
// in another variable
$results = print_r($arr, true); 

echo $results;

?>

Output:

Array
(
    [0] => Welcome
    [1] => to
    [2] => GeeksforGeeks
)

Reference: https://www.php.net/manual/en/function.print-r.php