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
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
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 *
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 #
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 #
Summary:Const is used instead of a fixed value of # define, and inline is used instead of # define a function. is an upgraded version of # define, in order to eliminate the defect of # define.the difference between #define和inlineDefine: defines a
#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
Define:
Define macros processed during pre-Compilation;
Only simple character replacement, no type detection
Typedef:Define the type alias for processing complex types Example: typedef int; Then: A; // defines a as Int.
Inline:The inline
You has no choice about the necessity to integrateyour observations,Your experiences, your knowledge into abstractideas, i.e., into principles.--ayn Rand, "philosophy:who Needs It" 1974Data Abstraction is a clear separation between the abstract
Linux is the most common is errno, usually when the error will give the global variable errno assignment, all of its possible values to view the Linux library files, the following is to view the results of the Linux
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