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Difference between typedef and define The following code is used to describe Typedef char * typedef_char;# Define define_char char * // No semicolon here Void main (INT argc, char * argv []){Char s [] = "ASDF ";Const typedef_char P = s; // char * const* P = 'B'; // The P pointer is a constant pointer. It cannot point to anything else, but the content to which it points can be changed. Cout Const define_c

1) #define是预处理指令, in the compilation preprocessing simple substitution, does not make the correctness check, does not have the meaning whether correctly still to carry in, only has in the compilation has been expanded the source program only then discovers the possible error and errors. Like what:#define PI 3.1415926In the program: Area=pi*r*r will be replaced with 3.1415926*r*rSuppose you write the number

1) #define是预处理指令, in the compilation preprocessing simple substitution, does not make the correctness check, does not have the meaning whether correctly still brings in, only when compiles the already expanded source program only then discovers the possible error and error. For example:#define PI 3.1415926In the program: Area=pi*r*r will be replaced with 3.1415926*r*rIf you write the number 9 in the #

Define is a pre-processing command in C language. It is used for macro definition, which can improve the readability of the source code and provide convenience for programming. Pre-processing commands start with "#", for example, include commands # include and macro-defined commands # define. Usually put in front of the source file, which is called preprocessing. Preprocessing refers to the work done before

1 :__ file __,__ line __, macro expanded, Middle Layer Macro _ File _ is the predefine macro of the compiler, indicating the absolute path of the file, but ASCII characters. Suppose you want to convert _ file _ into a wide character. Maybe you want # DEFINE _ wfile _ L ##__ file __ Wchar_t pszfilepath [] =__ wfile __; In this case, the compiler will prompt that "l1_file _" is an undeclared identifier. Why? If the parameter after # Is a macro, # will

Reference:typedef usage Http://www.cnblogs.com/ggjucheng/archive/2011/12/27/2303238.html#define用法: http://blog.csdn.net/benny5609/article/details/2314541====typedef=====There are generally two uses for typedef: one is to give the variable a new name that is easy to remember and makes sense, and the other is to simplify some of the more complex type declarations.egtypedef int size;typedef unsigned int WORD;typedef with arrays, pointersGeneral Array Dec

Original address: http://www.manongjc.com/article/491.html Const is the definition of a class member constant, which cannot be changed after the definition, and define we define global constants so that we can access them elsewhere but not change them. Note: Define cannot be defined in a class, and a const must be defined in a class, and the const must be access

// ================================================ ========================================// Title:// How to Write elegant code (2) -- # define? Const? Or enum?// Author:// Norains// Date:/// Tuesday 21-July-2009// Environment:// Wince5.0 + vs2005// ================================================ ======================================== # Define, const, and Enum: What are the associations between the thr

1. Simple macro definition #define Identifier substitution list (alternate list can be number, string literal, punctuation, operator, identifier, keyword, Word constants quantity.) Note: The substitution list is nullable. Typical error: #define N = 100 int a[n]; /* This will become an int a[= 100], which will be processed as an identification mark. #define N

# 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, you often cannot understand the essence of the command, and there is always some confusion here. The command is misused during programming, so that the running of the program is inconsistent with the expected pu

1. Define a simple constant: Define a constant to facilitate modification. (do not add a semicolon to the end !) # Define n 1000 It is equivalent to const int n = 1000, but slightly different. Define is a simple replacement instead of a quantity. 2. Define simple functions:

1. Simple define Definition# Define maxtime1000A simple maxtime is defined. It represents 1000. If you writeIf (I The compiler replaces maxtime with 1000 before processing this code.This definition looks similar to a normal constant definition const, but it is also different, because the definition of define is more like a simple text replacement, rather than bei

Original article address: Http://blog.csdn.net/kindazrael/article/details/8108868 Objective-C: # define Usage Analysis 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 #

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

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