c extern

The original intention of the C ++ language is "a betterC. as a language compatible with C, C ++ retains a part of the processStyle language features (known as "not completely Ground Object"), so it can define global variables and functions that do not belong to any class. however, C ++ is an object-oriented programming language.With function overloading, C ++ treats global functions differently from C. 2. Start with the standard header file An enterprise once gave the following interview questi

First, let's take a look at the definition of Baidu: Extern "C" contains a double meaning, which can be obtained literally: first, the target is "extern", and second, the target is "C. Let's explain these two meanings in detail. (1) functions or variables limited by extern "C" are of the extern type;

Recently in the C # to help the company to do an image recognition function, the use of third-party DLLs, in the process of invoking the DLL, there is a problem. Entrypointnotfoundexception exception. If you encounter this kind of exception, it is very likely that when you generate the DLL, the function output declaration isextern "C + +" _declspec (dllexport) int Add (int param1, int param2), because when using extern "C + +" The compiler will compil

1. Introduction C ++ The original intention of creating a language is "A Better C" But this does not mean C ++ Similar C The compilation and connection methods used by global variables and functions of the language are as follows: C The language is the same. As a desire and C Compatible language, C ++ Retains the characteristics of some procedural languages (known " Ground Object not completely " ), So it can define global variables and functions that do

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 conju

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 conju

assuming the C + + library file is libtest.a and the header file of the library is test.h, write this in test.h: Before and after the function to be exported: extern "C" {void Test_func ();.} nbs p; then use g++ to compile the source file of the link library, you can generate the C program can link the libtest.a. Of course, this libtest.a can also be linked by C + + programs. But this only solves the problem of linking. When compiling a C program,

Deep Exploration of the meaning of extern "C" in C ++ 1. Introduction C ++ was originally created as "a better C", but this does not mean that C ++ has global variables similar to C. And functions are compiled and linked in the same way as C. As a language compatible with C, C ++ retains A part of Procedural language features, so it can define global variables and functions that do not belong to any class. However, after all, C ++ It is an object-orie

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

1. Basic Explanations　　extern can be placed before a variable or function to indicate the definition of a variable or function in another file . Tip The compiler finds its definition in other modules when it encounters this variable and function. Also extern can be used for link designation .This means that extern has two functions:A. When it is in conjunction wi

About extern "C" 1. Introduction C ++ language was originally created as "a better C ", however, this does not mean that the compilation and connection methods used by global variables and functions similar to C in C ++ are the same as those in C. As a language to be compatible with C, C ++ retains the features of some procedural languages (known as "not completely oriented objects "), therefore, it can define global variables and functions that do no

Transferred from: http://www.cnblogs.com/yc_sunniwell/archive/2010/07/14/1777431.html1 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

# Include can contain the declaration of variables and functions in other header files. Why do we need the extern keyword? If I want to reference a global variable or function a, I just need to include # include This problem has always plagued me for a long time. After practice and searching for information, it is summarized as follows: I. header files First, let's talk about the header file. In fact, the header file has no effect on the computer. Sh

An explanation of the extern "C" usage in C + +extern "C" indicates a compilation protocol in which extern is the keyword attribute and "C" characterizes the compiler link specification. For the extern "C" can be understood as a mixed programming in the C++/C of the compilation instructions. Use "C" to compile and link

extern "C" is used(1) in C + +, references to functions and variables in the C language, in the case of a C language header file (assuming cExample.h), the following processing is required:extern "C"{#i nclude "CExample.h"}In the header file of the C language, only the extern type is specified for its external function, and the extern "C" declaration is not suppo

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 class. However, after all, C + + is an object-oriented programming language, in or

Turn from: extern "C" usage parsing-PinterestIntroductionC + + 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 different. The main purpose of

Source: http://www.cnblogs.com/yc_sunniwell/archive/2010/07/14/1777431.html 1Basic explanation: Extern can be placed before a variable or function to indicate that the definition of a variable or function is in another file, prompting the compiler to find its definition in other modules when it encounters this variable or function. In addition, extern can be used to specify links. That is to say,

This article turns from: http: // lpy999.blog.163.com/blog/static/117372061201182051413310/http://blog.csdn.net/ feitianxuxue/article/details/7204116 Thank bloggers, if there is infringement please notify the deletionWith # 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 p

original link1.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 class. However, after all, C + + is an object-oriented programming lan