define defragment

Const is used for the definition of class member constants. it cannot be modified after definition, and define is used to define global constants, so that we can access but cannot change it elsewhere, we will list the details below. note: define cannot be defined in... const is used for the definition of class member constants. it cannot be modified after definit

in our previous article, we introduced the use of PHP define examples, I believe that we have a certain understanding of define, today we introduce you to the PHP constant define and the difference between const detailed! A constant is a simple identifier. This value cannot be changed during script execution (in addition to the so-called magic constants, they a

Difference between typedef and # define ------ [Badboy ], Typedef and # define are commonly used to define the alias of an identifier and a keyword, but there is a key difference between them. Typedef is part of the language compilation process; # Define is a macro Definition Statement, which is not carried out during

Usage and difference between typedef and # define I. Usage of typedef In C/C ++, typedef is often used to define an alias for an identifier and a keyword. It is part of the language compilation process, but it does not actually allocate memory space, such: Typedef int;Typedef int array [10];Typedef (int *) pint; Typedef can be enhancedProgramBut it also has some disadvantages such as "non-intuitive.

Const and define all define constants in PHP, but what are their specific differences? In fact, very simple const is used for the definition of a class member variable, once defined and cannot change its value. Define defines a global constant that can be accessed anywhere the page define cannot be defined in the class

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 or exclude portions of a s

# DefineCreate a macro that is an identifier or parameterized identifier associated with the tag string. After defining the macro, the compiler can mark a string to replace each matching item of the identifier in the source file.Syntax # DefineIdentifierToken-string # DefineIdentifier(Identifier1,...,IdentifierN)Token-stringRemarks 1 # defineCommand to enable the CompilerToken-stringReplacing the source fileIdentifier. Only whenIdentifierIt is replaced only when a tag is formed. That is to say,

Usage of "#" and "#" in macroI. general usageWe use # to convert the macro parameter into a string, and # to combine the two macro parameters.Usage:# Include# IncludeUsing namespace STD; # Define STR (s) # s# Define cons (a, B) int (A ## e ## B) Int main (){Printf (STR (vck); // output string "vck"Printf ("% d/N", cons (2000); // 2e3 output:Return 0;} 2. When the macro parameter is another macroIt should be

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.You can use the Define () function to define constants. After php5.3.0, you can use the Const keyword to define c

In general, we define a constant using # define, #define的本质是文本替换, for example, # define INT_PTR int*, when we use a int_ptr,int_ptr a, B, which is equivalent to an INT * A, A, a, b; That is, define a pointer variable A and integer variable B, which is a common scenario for #

1 NO parameter macro definitionThe macro name of the parameterless macro is not followed by a parameter.The general form of its definition is:#define Identifier stringWhere the "#" indicates that this is a preprocessing command. All that begin with "#" are pre-processing commands. "Define" defines the command for the macro. "Identifier" is the name of the macro defined. A "string" can be a constant, an expr

Note: Define cannot be defined in a class, and the const must be defined in a class, and the const must be accessed by the class name:: Variable name 1. Const is used for class member variable definition once defined and cannot change its value. Define defines global constants that can be accessed anywhere.2, define can not be defined in the class and Const.3. C

The difference between define () and const: Define () defines constants during the execution period, while Const defines constants at compile time. This will have a slight speed advantage (ie a slightly better performance), but it is not worth considering unless you are building a large, high concurrency system. Define () puts constants into the global scope, e

Original article address: Http://blog.csdn.net/kindazrael/article/details/8108868 In C, Preprocessor is a powerful tool that makes your code easier to read and modify. With preprocessing code, you can redefine a part of the code to make your code more suitable for your style. Preprocessor is processed in advance before the code is compiled. The pre-processing code starts with a pound sign.1. About #define #defineDeclarations are mainly used to assign

#define宏定义在C系开发中可以说占有举足轻重的作用. The underlying framework does not have to say, in order to compile optimization and convenience, as well as cross-platform capabilities, macros are heavily used, it can be said that the bottom of development left define will be unable to move. When developing at a higher level, we put more emphasis on business logic and seem to have little use and reliance on macros.But the ben