php's function print_X is print_r(), which is used to print variables and display them in a more understandable form.
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Syntax:
bool print_r ( mixed $expression [, bool $return ] )
Parameter description:
$expression: The variable to be printed, if given What is output is a string, integer or float type variable, and 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 $a = array ('a' => 'apple', 'b' => 'banana', 'c' => array ('x','y','z')); print_r ($a); ?>
The output result is:
Array ( [a] => apple [b] => banana [c] => Array ( [0] => x [1] => y [2] => z ) )
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