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PHP uses the Define () function to define a constant. The so-called constant refers to the value of the amount of constant, this article collects a few about the PHP constants of the article, I hope that you understand the PHP constants help, come together to see it. The definition of 1.PHP constants and the use of examples to explain constants we can understand as the amount of constant value. Constants ar

Transferred from: http://www.cnblogs.com/kerwinshaw/archive/2009/02/02/1382428.htmlI. Usage of typedefA typedef is commonly used to define an identifier and an alias for a keyword in the C + + language, which is part of the language compilation process, but it does not actually allocate memory space, such as:typedef int INT;typedef int ARRAY[10];typedef (INT*) PINT;typedef can enhance the readability of the program, as well as the flexibility of ident

First, preprocessing commands he is not a constant!!!! Let's look at a piece of code #define @ "Avatar" if (false) { #define AVATAR @ " NSLog"} (Avatar); How much does this code output, we define "avatar" for 60, and then redefine "Avatar" in a code that never executes, the code in theif statement never executes, but at compile time , the compi

In this paper, we mainly record the pre-C + + preprocessor directives, and the common preprocessing directives are: #空指令, without any effect #include包含一个源代码文件 #define定义宏 #undef取消已定义的宏 #if如果给定条件为真, the following code is compiled #ifdef如果宏已经定义, the following code is compiled #ifndef如果宏没有定义, the following code is compiled #elif如果前面的 # If the given condition is not true and the current condition is true, compile the fo

The so-called constant is a simple identifier. The value cannot be changed during script execution. Constants are case sensitive by default. Usually, constant identifiers are always uppercase. Constants can only contain scalar data (Boolean, Integer, float, and string). You can define resource constants, but avoid them as much as possible, because they cause unpredictable results. Define partMacros can be

This article is guided by:C # preprocessor directives are never translated into executable code commands, but can affect all aspects of the compilation process, common preprocessor directives have # define, #undef, #if, #elif, #else和 #endif, and so on, the following describes C # use # Define an instance of conditional compilation.In C #, conditional compilation directives are used to conditionally include

#ifndef the use of #define#endif#ifndef in the fileThe #ifndef of the first piece, this is a very important thing. For example, you have two C files, and these two C files include the same header file. At compile time, these two C files are compiled into a running file together, so the problem comes with a lot of conflicting statements.or the contents of the head file in #ifndef and #endif. Regardless of whether your header file will be referenced by

In php5, const, define, and static 1. in const programming, we generally use constants to define the constant values that cannot be changed during runtime. let's take a look at const in php, there is nothing to say about this, just to improve the knowledge. When defining a constant, we can use const to modify the constant. the constant modified with const is a bit different from other constants: const,

The difference between defining a variable and declaring a variable is that defining an operation that will generate memory allocation./* Module1.h */Int a = 1;/* define int a */In the. h file of Module 1 */ /* Module1.c */# Include "module1.h"/* contains the. h file of Module 1 in Module 1 */ /* Module2.c */# Include "module1.h"/* contains the. h file of Module 1 in Module 2 */ /* Module3.c */# Include "module1.h"/* contains the. h file of Module 1 i

This article provides a detailed analysis of the differences between const and define in php. For more information, see This article provides a detailed analysis of the differences between const and define in php. For more information, see 1. const is used for defining class member variables. Once defined, the value cannot be changed. Define defines global c

1. Const is used for class member variable definition, once defined and cannot change its value. Define defines global constants that can be accessed everywhere. 2. Define cannot be defined in a class and const can. 3. Const cannot define constants in conditional statements Copy CodeThe code is as follows: if (...) { Const FOO = ' BAR '; Invalid } But if (...) {

Define reference relationships : In this tutorial, each dimension of your cube has been directly linked to a table in the fact data table of the measurement value group based on the relationship between the primary key and the foreign key. In Lesson 3rd and lesson 4th, you will not directly link to a table (called a snowflake table) in a fact data table) the dimension attribute in is included in the dimension that is directly linked to the fact da

We all know that define is defined as constants, what if constants are defined in the class? Certainly cannot use define, but uses the const, the following example: The code is as follows Copy Code define (' php ', ' I love php ');////Outside the class usually defines constants if (defined (' php ')) { echo ' php is defined! ' ; T

The use of define is only a pure substitution function, and the substitution of the macro definition is the replacement that the preprocessor handles. One: Simple macro-definition usage Formatting: Replacing content with #define Identifiers The replacement can be numbers, characters, strings, special characters, and spaces, and what will be replaced with what is behind it. For example: #

This article to share the content is detailed in the PHP constant: Define and const difference, has a certain reference value, the need for friends can refer to A constant is a simple identifier. This value cannot be changed during script execution (in addition to the so-called magic constants, they are not constants). Constants are case sensitive by default. Usually, constant identifiers are always uppercase. can be used

"Q" When defining constants in PHP, what is the difference between const and define? The "answer" uses the const to make the code easy to read, and the const itself is a language structure, and define is a function. In addition, const is much faster to compile than define. (1). Const is used to define a class member v

1. const is used for defining class member variables. once defined, the value cannot be changed. Define defines global constants that can be accessed anywhere. 2. define cannot be defined in the class, but const can. 3. const cannot define the constant if (...) {constFOO amp; #39;... SyntaxHigh in the condition statement. 1. const is used for defining class memb

# Ifndef # define # endif usage, # Ifndef # define # endif usage # Ifndef # Ifndef in the header, which is critical. For example, you have two C files, both of which include the same header file. During compilation, these two C files need to be compiled into a runable file together, so the problem arises and a large number of declarations conflict. Put the header file content in # ifndef and # endif. Wheth

1. Wide screen height and common size#define SCREEN_WIDTH ([UIScreen mainscreen].bounds.size.width)#define Screen_height ([UIScreen mainscreen].bounds.size.height)#define Navigationbar_height 44.0f#define Tabbar_height 49.0f#define Statusbar_height 20.0f#

Original address: http://blog.csdn.net/xiaogou56a/article/details/21340213Define used to define modulesRequire used to load modules1Because defining a module may depend on other modules, and of course the simplest case is to not rely on other modules, then you can write:[JavaScript]View Plaincopy Inside file My/shirt.js: Define ({ Color: "Black", Size: "Unisize" }); Official ex