如何在CRO文件中调用CPP文件中的函数,反之亦然在ANDROID NDK中？

Question

我无法从c文件调用cpp文件中的函数,也无法从ndk本身的cpp文件调用c文件中的函数.

我也试过使用extern"C"{}.

粘贴我在这里尝试的代码供参考.

CFileCallingCpp.c:

#include "CFileCallingCpp.h"
//#include "custom_debug.h"
#include "CppFile.h"





void tempFunc() {

}

void printTheLogs() {
    //Its not possible to make use of the CPP class in c file
//  CCustomDebug cls;
//  cls.printErrorLog("This is the error log %d %s", 54321, "aaaaaaaaaaaaaaaaaa");
//  cls.printErrorLog("EXAMPLE", "This is the error log %d %s", 54321, "aaaaaaaaaaaaaaaaaa");
    printTheLogs1();
//  tempFunc();
}

CFileCallingCpp.h:

#ifndef _CFILECALLINGCPP_H_
#define _CFILECALLINGCPP_H_

void printTheLogs();


#endif

CppFile.cpp:

#include "CppFile.h"
#include "custom_debug.h"
#include "CFileCallingCpp.h"

void printTheLogs1() {
    CCustomDebug::printErrorLog("This is the error log %d %s", 54321, "aaaaaaaaaaaaaaaaaa");
    CCustomDebug::printErrorLog("EXAMPLE", "This is the error log %d %s", 54321, "aaaaaaaaaaaaaaaaaa");
}

#if defined(__cplusplus)
extern "C" {
#endif

void callCFileFunc() {
    printTheLogs();
//  printTheLogs1();
}


#if defined(__cplusplus)
}
#endif

CppFile.h:

#ifndef _CPPFILE_H_
#define _CPPFILE_H_

void printTheLogs1();


#endif

我得到的错误:

    sh-4.1$ /cygdrive/c/Android/android-ndk/ndk-build
    SharedLibrary  : libJNIExInterface.so
    D:/EclipseWorkspace/NativeExample/obj/local/armeabi/objs-debug/JNIExInterface/CppFile.o: In function `callCFileFunc':
    D:/EclipseWorkspace/NativeExample/jni/CppFile.cpp:15: undefined reference to `printTheLogs()'
    D:/EclipseWorkspace/NativeExample/obj/local/armeabi/objs-debug/JNIExInterface/CFileCallingCpp.o: In function `printTheLogs':
    D:/EclipseWorkspace/NativeExample/jni/CFileCallingCpp.c:18: undefined reference to `printTheLogs1'
    collect2: ld returned 1 exit status
    make: *** [/cygdrive/d/EclipseWorkspace/NativeExample/obj/local/armeabi/libJNIExInterface.so] Error 1
    sh-4.1$

如果有人知道如何从ANDROID-NDK中的c代码调用cpp代码,请告诉我.

此致,
SSuman185

Answer 1

如果从ac文件中定义的cpp文件调用函数,则可以使用

extern "C" void c_func(); // definition

// from a cpp file
c_func();

你可以反过来,从ac文件中调用一个cpp文件中的函数

// implemnatation in cpp file
extern "C" void cpp_func()
{
    // c++ code allowed here
}

// declaration in .h file
#ifdef _CPLUSPLUS
extern "C" void cpp_func();
#else
extern void cpp_func();
#endif

// from the c file
....
cpp_func();
.....

Answer 2

应该extern "C"位于 C 源代码包含的头文件中，而不是 C++ 源文件中。C++ 源文件包含的 C 头文件也是如此。