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Introduction to preprocessing Directives
One, macro definition without parameters
Second, macro definition with parameters
Description: This C language topic is the prelude to learning iOS development. And for programmers with an object-oriented language development experience, you can quickly get started with C language. If you don't have programming experie
Original post http://hi.baidu.com/bwandmff/blog/item/56876b30a31d519da9018e9a.htm
Before discussing global variables, we must first understand several basic concepts:
1. compilation unit (module ):Today, when IDE development tools are widely used, many developers are no longer clear about the concepts of compilation. Many programmers are most afraid of handling connection errors ), because it does not give the specific location of your program errors as a compilation error, you are often annoy
Macro definition is a precompiled function, precompilation is also known as preprocessing, is the preparatory work for the compilation of the stage. Handle the instructions at the beginning of the #, such as copy #include contained file code, #define宏定义的替换, conditional compilation, etc.Benefits of using macro definitions: The benefits of using macro definitions can improve the versatility and readability of programs, reduce inconsistencies, reduce inp
6.3 first recognized class
Class introduces some new syntax: three new object types and some new semantics.6.3.1 class definition syntax
The simplest form of class definition is as follows:
Class ClassName:
.
.
.
The class definition is the same as the function definition (def statement). It must be executed befo
/Home/TACE/openav/source/seamlessmessage/cpaoflt. O: In function 'cpaoflt: get_m_strprmair () const ':Cpaoflt. cpp :(. Text + 0x0): Multiple definition of 'cpaoflt: get_m_strprmair () const'/Home/TACE/openav/source/seamlessmessage/cpaoflt. O: cpaoflt. cpp :(. Text + 0x0): first defined here
During the compilation process, GCC reports the multiple definition of function errors, mainly including the followin
There are two types of macro definitions: macro definitions without parameters and macro definitions with parameters.
Macro definition without ParametersThe general format of macro definition without parameters is:
# Define macro name string# Define PI 3.1415926Main (){Float area, R;Printf ("Area = % F", pI * r * R );}In the above program, the macro pi is used to replace the string 3.1415926. The advantage
Ask questions:If you have such a template:class test{public: static std::string info;};What is right (by compiling) for several of the following definitions?Template stringtestint>::info ("123"); templatestringTest"123"); templatestringTest:: Info;templatestringtestint>:: info; templatestringtestint>:: info (); templatestringTestIn order not to affect the analysis and judgment, I put the answer color into a relatively light color, the following is the answer:
Template
Template
We are in the program design, always use the definition of variables and variable declarations, but sometimes we are not very clear about the concept, know how it is used, but do not know how to do, the following I simply put their differences are described as follows:
There are two things about the declaration of a variable:(1) One is the need to establish storage space (definition, declaration). For exam
Class Definition details in C ++
Member variables
Each class can have no members or multiple members. The members can be data, functions, or type aliases.
A class can contain several public, private, and protected parts. Members defined in the public part can be accessed by all code using this type; Members defined in the private part can be accessed by other class members. Protected can be accessed by the quilt class.
Constructor
A function that has
variable declarations and variable definitions
Variable definitions: Used to allocate storage space for a variable, and to specify an initial value for a variable. In a program, a variable has and has only one definition.
Variable declaration: Used to indicate the type and name of a variable to a program.
A definition is also a declaration, an extern declaration is not a
Detailed description of the definition and execution principle of asynchronous Action under ASP. net mvc, asp. netmvc
The Controller creation Wizard provided by Visual Studio creates a Controller type inherited from the abstract class Controller by default. Such a Controller can only define synchronous Action methods. To define an asynchronous Action method, we must inherit the abstract class AsyncController. This article describes two different async
Matlabsix ways to customize a functionN1, function file + Call Function (command) file: m file to define a custom function separately;N2, function file + sub-function: Defines an m file with multiple custom functions;N3,Inline: No m file, direct definition; N4, anonymous function;N5,syms+subs: No m file, direct definition; N6, String +subs: No m file, directly defined. ------------1 , function Files + calli
1,Use a # Before a parameter in a Preprocessor macro. The Preprocessor converts this parameter to a character array. (Original article: when you put a # Before an argument in a Preprocessor
Macro, The Preprocessor turns that argument into a character array. This,
Combined with the fact that character arrays with no intervening punctuation are concatenated into a single character array, allows you to make a very convenient macro for printing the values of variables during debugging)
# Include "io
(1) inline function (from the third edition of C ++ primer)
In the function declaration or definition, add the keyword inline before the function return type to specify min () as inline.
Inline int min (INT first, int secend ){/****/};
The inline function must be visible to the compiler so that it can expand the function within the call point. Unlike non-inline functions, inline functions must be defined in each text file that calls the function. Of c
I found a small problem when writing a program today, as shown below:
1 #include 2 #include 3 4 using namespace std; 5 template 6 class Node 7 { 8 private: 9 Node10 public:11 T data;12 Node(const T item,Node13 void InsertAfter(Node14 Node15 Node16 };17 18 template19 Node20 21 template22 Node23 {24 return next;25 }26 27 int main(void)28 {29 return 1;30 }
The following error occurs during compilation:
If the default value of the
I studied definitions and declarations in C. The concepts are mainly embodied in functions, that is, declarations only tell the compiler that there is such a thing that there is no specific operation to define functions, the definition is specific to what the function should do.
Then I got confused when I came to C ++ and C #. What should I say about the class? What should I say about the objects of the definitio
In the C and C + + languages, an identifier is allowed to represent a string, called a macro, which can be a constant, an expression, a format string, and so on. When compiling preprocessing, all occurrences of the "macro name" in the program are substituted with the string in the macro definition, which is called "macro substitution" or "macro expansion". A macro definition is done by a macro
1 OverviewUsed preprocessing commands starting. For example, include the command # include and macro definition command # define. In the source program, these commands are placed outside the function, and are generally placed before the source file. They are called preprocessing.
Preprocessing refers to the work done before the first scanning (lexical scanning and syntax analysis) of compilation. Preprocessing is an important function of C language, w
Packagecom.mycom.processDefinition;ImportJava.io.File;Importjava.io.IOException;ImportJava.io.InputStream;Importjava.util.ArrayList;ImportJava.util.LinkedHashMap;Importjava.util.List;ImportJava.util.Map;ImportJava.util.zip.ZipInputStream;ImportOrg.activiti.engine.ProcessEngine;ImportOrg.activiti.engine.ProcessEngines;Importorg.activiti.engine.repository.Deployment;Importorg.activiti.engine.repository.ProcessDefinition;Importorg.apache.commons.io.FileUtils;Importorg.junit.Test; Public classproces
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