php print_r what is

php print_r is a built-in function in php, used to print variables and display them in a more understandable form. The syntax of this function is "bool print_r (mixed $expression [, bool $return])" .

PHP print_r() function

print_r() function is used to print variables to make it easier Demonstration of understanding.

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

Syntax

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

Parameter description:

$expression: variable to be printed, if Given a variable of type string, integer or float, 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 If set to true, there will be a return value, which is an easy-to-understand string information.

Example

<?php
$a = array (&#39;a&#39; => &#39;apple&#39;, &#39;b&#39; => &#39;banana&#39;, &#39;c&#39; => array (&#39;x&#39;,&#39;y&#39;,&#39;z&#39;));
print_r ($a);
?>

The output result is:

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

Set $return parameter:

Example

<?php
$b = array (&#39;m&#39; => &#39;monkey&#39;, &#39;foo&#39; => &#39;bar&#39;, &#39;x&#39; => array (&#39;x&#39;, &#39;y&#39;, &#39;z&#39;));
$results = print_r ($b, true); // $results 包含了 print_r 的输出结果
?>

The above information has no output result. Because the output result is assigned to the $results variable.

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