PHP print_r() function

Author：Eve Cole Update Time：2024-12-28 09:24:01

The print_r() function is used to print variables and display them in a more understandable form.

PHP version requirements: PHP 4, PHP 5, PHP 7

grammar

 bool print_r ( mixed $expression [, bool $return ] )

Parameter description:

$expression: The variable to be printed. If a string, integer or float type variable is given, the variable value itself will be printed. If an array is given, the keys and elements will be displayed in a certain format. object is similar to an array.

$return: Optional, if true, the result will not be output, but the result will be assigned to a variable, if false, the result will be output directly.

return value

$return will only return a value if set to true , which is an easy-to-understand string information.

Example

<?php $a = array ( ' a ' => ' apple ' , ' b ' => ' banana ' , ' c ' => array ( ' x ' , ' y ' , ' z ' ) ) ; print_r ( $a ) ; ?>

The output is:

 Array( [a] => apple [b] => banana [c] => Array ( [0] => x [1] => y [2] => z ))

Set the $return parameter:

Example

<?php $b = array ( ' m ' => ' monkey ' , ' foo ' => ' bar ' , ' x ' => array ( ' x ' , ' y ' , ' z ' ) ) ; $results = print_r ( $b , true ) ; // $results contains the output results of print_r ?>

There is no output result for the above information, because the output result is assigned to the $results variable.