c extern

Description(1) The function or variable restricted by extern is of the extern type: A. extern variable declaration. For example, if the file a. c needs to reference the int v variable in B. C, you can declare externint V in A. C, and then you can reference the variable v. Note that the link property of the referenced variable V must be external, that is,. c. the

With # include to include the declarations of variables and functions in other header files, why do I need the extern keyword?If I want to refer to a global variable or function A, I just have to include #includeThis question has been a paradox for a long time, after the practice and find information, the following summary:First, the header fileFirst of all, the head file, in fact, the first file on the computer does not work, she just in the pre-comp

In Windows Driver development, if you are using C + + development, then you must be in some key function money plus extern c keyword, otherwise compiled function, and C language compiled function is different, cause the driver can notbe effectively identified.The most critical is the DriverEntry function, if the use of C + + developed CPP, then, the compiler compiled function will be _driverentry, when it is actually compiled with c is [email protecte

Usage analysis of extern "C"Deep Exploration of the meaning of extern "C" in C + +1. IntroductionThe C + + language was originally created as "A better C", but this does not mean that C + + global variables and functions in C + + are compiled and connected in exactly the same way as C. As a language that wants to be compatible with C,C + + retains some of the characteristics of a procedural language (known

The main function of extern "C" is to call other C code correctly. After extern "C" is added, it indicates that the code of the compiler is compiled in C language instead of C ++. C ++ supports function overloading. Therefore, during function compilation, the parameter types of the function are added to the compiled code, not just the function name; C language does not support function overloading. Therefor

extern "C" usage parsingAuthor author Jason Ding , Link http://www.jianshu.com/p/5d2eeeb93590IntroductionC + + retains some of the characteristics of a procedural language, so it can define global variables and functions that are not part of any class. However, after all, C + + is an object-oriented programming language, in order to support the overloading of functions, C + + to the global function of the processing method and C are obviously differen

"Turn from": http://www.cnblogs.com/rollenholt/archive/2012/03/20/2409046.html 1. IntroductionThe C + + language was originally created as "A better C", but this does not mean that C + + global variables and functions in C + + are compiled and connected in exactly the same way as C. As a language compatible with C, C + + retains some of the features of the procedural language (known as "not completely object-oriented"), so it can define global variables and functions that are not part of any cl

original link: http://www.cnblogs.com/rollenholt/archive/2012/03/20/2409046.html1.IntroductionThe C + + language was originally created as "A better C", but this does not mean that C + + global variables and functions in C + + are compiled and connected in exactly the same way as C. As a language compatible with C, C + + retains some of the features of the procedural language (known as "not completely object-oriented"), so it can define global variables and functions that are not part of any cla

1 Basic explanation : extern can be placed before a variable or function to indicate the definition of a variable or function in another file, prompting the compiler to find its definition in other modules when encountering this variable and function. Also extern can be used for link designation. That is, the extern has two functions, the first, when it is in con

Deep Exploration of the meaning of extern "C" in C + + Source: Pconline 2005-08-30 10:04:00 Author: Song Baohua Editor: Moningfeng 1. Introduction The C + + language was originally created "A better C", but this does not mean that the C-language-like global variables and functions in C + + are compiled and connected in exactly the same way as the C language. As a language intended to be compatible with C, C + + retains some of the characteristics

1. The introduction of the C + + language was originally created "A better C", but this does not mean that C + + similar to the global variables and functions are used in the compilation and the connection method is identical to the C language. As a language intended to be compatible with C, C + + retains some of the characteristics of the procedural language (known as "not completely object-oriented"), so it can define global variables and functions that do not belong to any class. But, after

"# ifndef _ incvxworksh, # DEFINE _ incvxworksh, and # endif" in the header file is used to prevent the header file from being repeatedly referenced. So # Ifdef _ cplusplusExtern "C "{# Endif# Ifdef _ cplusplus}# Endif What is the role? We will discuss it one by one below. 3. Deep encryption extern "C" Extern "C" contains double meanings, which can be obtained literally: first, Target Is "

# Endif/* _ incvxworksh */ AnalysisObviously, the compilation macro "# ifndef _ incvxworksh, # DEFINE _ incvxworksh, and # endif" in the header file is used to prevent the header file from being repeatedly referenced. So # Ifdef _ cplusplusExtern "C "{# Endif# Ifdef _ cplusplus}# Endif What is the role? We will discuss it one by one below. 3. Deep encryption extern "C" Extern "C" contains a doubl

_ incvxworksh, # DEFINE _ incvxworksh, and # endif" in the header file is used to prevent the header file from being repeatedly referenced. So # Ifdef _ cplusplusExtern "C "{# Endif# Ifdef _ cplusplus}# Endif What is the role? We will discuss it one by one below. 3. Deep encryption extern "C" Extern "C" contains a double meaning, which can be obtained literally: first, the target is "

This article was reproduced from: http://www.cnblogs.com/rollenholt/archive/2012/03/20/2409046.html1.IntroductionThe C + + language was originally created as "A better C", but this does not mean that C + + global variables and functions in C + + are compiled and connected in exactly the same way as C. As a language compatible with C, C + + retains some of the features of the procedural language (known as "not completely object-oriented"), so it can define global variables and functions that are

__incvxworksh, #define __incvxworksh, #endif" in the header file prevents the header file from being repeatedly referenced.So#ifdef __cplusplusextern "C" {#endif#ifdef __cplusplus}#endifWhat is the role of it? We will be in the following one by one lanes.3. Deep disclosure of extern "C"extern "C" contains a double meaning, literally: First, the object it modifies is "e