php check if variable null

#一, PHP variable definition: Variables are used to store values, such as numbers, text strings or arrays, V: string/integer/double/array/object Naming rules: 1. The variable name of PHP is case-sensitive. 2. The variable name must begin with $3,

PHP is a loosely typed programming language, and it is an indispensable step in a function to examine the "type" of the passed parameter value and whether the value is null or NULL. Type check Starting with PHP5, PHP allows type

Analysis of variable reference and destruction mechanism in PHP, and destruction of php. Analysis of variable reference and destruction mechanism in PHP. php destruction examples in this article analyze the variable reference and destruction

Php pre-defined variable help (with instance ). From php4.1.0, the preferred method for getting external variables is to use the Superglobal variables mentioned below. Prior to this, people were either dependent on register_globals, or long

A simple comparison between empty () and isset. The code is as follows:Copy code $ Var = 0; // The result is true because $ var is empty.// The result is true because $ var = 0If (empty ($ var) {echo '$ var is either 0 or not set at all ';}//

The preferred method for php to obtain external variables is to use the hyperglobal variables mentioned below. Prior to this, people were either dependent on register_globals or long pre-defined PHP array ($ HTTP _ * _ VARS ). From PHP5.0.0, PHP

Now the development of the site to use the Smarty framework template, feel very good, better realize the PHP source code and the separation of HTML. Now share some common variables of smarty. 1, smarty_dir SMARTY directory Locate the full system

The preferred method for php to obtain external variables is to use the hyperglobal variables mentioned below. Prior to this, people were either dependent on register_globals or long pre-defined PHP array ($ HTTP _ * _ VARS ). Starting from PHP5.0.0

PHP Tutorial Configuration Chinese Narration Let's see what you see, php.ini. [PHP] ;;;;;;;;;;;; WARNING;;;;;;;;;;;;; This is the default settings file for new PHP installations.; By default, PHP installs itself with a configuration suitable for;

Solution Objective: determine if a variable is empty This article has compiled some commonly used in PHP, the judgment variable is empty method, shares to everybody.1,isset function : Determine whether the variable is initializedDescription: