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The difference between #define, const, typedef#define is not defining variables, it's just for text substitution.For example:#define PI 3.1415926float Angel;angel=30*pi/180;Then, when the program is compiled, the compiler will first "#define PI 3.141

1. Define (that is, host variable)The main role of the host variable is to act as an alternative variable, a medium in which the host environment can interact with Oracle . When you define a host variable by define, you must specify the variable

Macro definition in many languages can see its shadow, C #, C++,c, and so on, especially the system API inside a lot of macro definition, looking very bluffing people. Reasonable use of macro definition, you can make your code look more standardized,

There are many places in the C language where macro definitions are used, such as in header files to prevent header files from being repeatedly included: #ifndef ctest_header_h #define CTEST_HEADER_H /header file content #endif Many macro

Jency LeeLinks: http://www.cnblogs.com/Jency/articles/C_Cplusplus_define.html1. Simple define Definition #define MaxTime + A simple maxtime is defined, which represents 1000 if you write in the program if (i Compiler replaces maxtime with 1000

Let's look at a few examples (1) struct{int x; int y;} Test1; Well, define the structure test1, test1.x and test1.y can be used in the statement. (2) struct test {int x; int y;} Test1; Well, define the structure test1, test1.x and test1.y can be

The Define () function defines a constant.define () functions: Defines a constant. Constants is much like variables, except for the following differences: constants [constant] and variables [variable] There are many similarities, so it is easy to

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

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 *

1) # define is a pre-processing command. It is a simple replacement during compilation and pre-processing, and does not check the correctness. It does not mean that it is correct or not, possible errors are detected and reported only when the