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The Magic usage of C + + macro commands. First look at the following three statements: #define CONN (x,y) x# #y #define TOCHAR (x) #@x #define TOSTRING (x) #x 1. # # Connection operator # #表示连接 (token pasting, or token concatenation,merge two tokens into one while expanding macros). x# #y表示什么. Represents x connection Y, for example: int n = Conn (123,456);

1) #define是preprocessing Directives, which is performed when the preprocessing is compiledsimple substitution, no correctness check, whether the meaning is correct or not, only when compiling the source program has been expanded to find possible errors and error. For example: #define PI 3.1415926 Program: Area=pi*r*r will be replaced with 3.1415926*r*r if you write the number 9 in the #

: This article mainly introduces the difference between const and define in php (supplement). If you are interested in PHP tutorials, refer to it. A constant is the identifier (name) of a simple value ). As its name implies, this value cannot be changed during script execution (except for so-called magic constants, they are actually not constants ). Constants are case sensitive by default. Constant identifiers are always capitalized. You can use the

In # define, the standard defines only # and # #两种操作. #用来把参数转换成字符串, # #则用来连接两个前后两个参数, turn them into a string.#define CONN (x, y) x# #y//connection X, Y#define TOCHAR (x) #@x//Plus Single quote#define TOSTRING (x) #x//plus double quotation marksRecently read the COM related information, see CCmdTarget Implement COM int

#define是C语言中提供的宏定义命令, the main purpose is to provide programmers with a certain degree of convenience in programming, and to a certain extent to improve the efficiency of the program, but students often do not understand the nature of the command, always here to create some confusion, the programming misuse of the command, So that the operation of the program is inconsistent with the intended purpose, or read the program written by others, the results

Macro definition in C # define usage, # Define is a macro definition Command provided in C language. Its main purpose is to provide programmers with some convenience in programming and improve the program running efficiency to a certain extent, however, when learning this command, students often cannot understand the essence of the command, and there is always some confusion here. The command is misused dur

Value of Do{}while (0) When macro definition (#define) in C languageRecently found in the code of the new company everywhere used do{...} while (0), Google a bit, found that stack overflow early on a lot of discussion, summed up the discussion, coupled with their own understanding, do{...} while (0) the value is mainly reflected in:1. Increase the adaptability of the CodeThe following macro definition does not use do{...} while (0)#

In applications, define is often used to define common parameter information to increase program readability and reliability. In PHP, the constant name is a simple identifier, which cannot be changed during the execution period and is case sensitive by default. Constants are always capitalized. Note: The third parameter in define can be used to set whether the co

ArticleDirectory Introduction 1. Using a function 1.1. methods defined internally 1.2. Methods added to the prototype 2. Using Object literals 3. Singleton using a function Summary 3 ways to define a javascript classintroduction Javascript is a very flexible object-oriented language when it comes to syntax. in this article you can find three ways of defining and instantiating an object. even if you have already picked y

Original article link Try to use const and inline instead of # define It is also called: Try to use the compiler instead of preprocessing. Cause: (1) # Define aspect_ratio 1.653Pre-compileProgramAspect_ratioReplace 1.653When a compilation error occurs, only the 1.653But aspect_ratio cannot be tracked., Not easy to debug (2) # Define max (A, B) (a)> (B )? (

Document directory Link definition order Define a local link Style Define link StyleCSS provides specific tools for some special effects, which are called "pseudo classes ". The following describes the four pseudo classes that are often used to define link styles. They are: : Link : Visited : Hover : Active Because we n

increases the difficulty of project management. IBM Rational Unified Process is implemented to manage and distribute the entire project development process. It is browser-based, A Customizable software development process platform. It focuses on the software development industry-recognized Optimization Method and manages the allocation of different elements in the development process.　　 Generally, the default RUP can meet the needs of some users. Users can publish and use it simply by deleting

# DefineAndConstDifference Although they feel "almost" in use, what are their differences in implementation? See the following code: # Define T 13/* use # A constant defined by define T */ Int main () { Const int T = 13;/* a constant defined by const */ Int n = T;/* assign t to N */ Int M = T;/* assign t to M */ } 1.Difference: The biggest difference between const and #

[Code sea shell TC] Use View to define dynamic Class, sea shell tcPreface In TC, Persistent Class corresponds to Table. Define a Persistent Class. updatedb generates the corresponding table. In the development environment of TC, a corresponding username will generate a table under this username In the formal environment, because adm, su, and key are used, the corresponding table will be generated under thes

PHP uses array_fill to define multi-dimensional arrays. array_fill is multi-dimensional. PHP uses array_fill to define multi-dimensional arrays. array_fill this article describes how PHP uses array_fill to define multi-dimensional arrays. Share it with you for your reference. Specific Analysis: for example, PHP uses array_fill to

The Meaning of # # # in C++/C macro definition (define)# # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # define.#是字符串化的意思, the # that appears in the macro definition is a string that is followed by a parameter;eg#define STRCPY__ (DST, SRC) strcpy (DST, #src)Strcpy__ (BUFF,ABC) equivalent to strcpy__ (buff, "abc")# #是连接符号, connect the paramet

First, #define宏定义1. Macro definition, like this is the macro definition: #define PI 3.14159;2. Macro Definition Format: Macro value #define Macro name is the macro to be defined, usually denoted by a meaningful name in uppercase, and the macro value is the constant represented by the macro. ；3. #define是预编译指令;4. The ess

After reading some frameworks, many of them use define to define many system parameters at the system core entrance. However, we recently see that some of them are defined in $ _ SERVER and even $ _ ENV. Although all functions can be implemented, I have been confused. What are the advantages of this definition? Or... after reading some frameworks, many of them use defin