php bits and pieces

Define constants

define('LOGENABLE', true);

Initialize an empty array

$arr = array();

Get the length of the array

$length = count($arr);

Output statement

echo, printf, print_r, var_dump

Introduce (call) other php

require(), include()

These two functions are basically the same, the difference is that require fails After that, a fatal error will be given, and after include fails, just a warning will be given.