C/C++ mixed programming

2011/05/24 - [Programming/C++] - C/C++ mixed programming
not to use name mangling
C library 작성시 나중에 C++에서 활용될 가능성을 미리 염두해 두고, 헤더 파일 처음과 마지막에 extern "C" {}가 조건부 컴파일되게 한다

//	externc.cpp
#include <iostream>

using namespace std;

extern "C" int max(int a, int b)
{
	if ( a > b )	return	a;
	else			return	b;
}

int main(void)
{
	int	im	=	max(100, 30);

	cout << "int max = " << im << endl;
}
/*
$ g++ -o externc externc.cpp 
$ ./externc 
int max = 100
$ nm externc | grep max
000000000040097a t _GLOBAL__I_max
00000000004008d4 T max
*/

//	max.h
int max(int a, int b);

//	max.c
int max(int a, int b)
{
	if ( a > b )	return	a;
	else			return	b;
}

//	cppmain.cpp
#include <iostream>
#include "max.h"

using namespace std;

int main(void)
{
	int	im	=	max(100, 30);

	cout << "int max = " << im << endl;
}

/*
$ gcc -c max.c
$ g++ -c cppmain.cpp 
$ g++ -o cppmax cppmain.o max.o
cppmain.o: In function `main':
cppmain.cpp:(.text+0x13): undefined reference to `max(int, int)'
collect2: ld returned 1 exit status
*/

//	max.h
#ifdef	__cplusplus
extern "C"	{
#endif

int max(int a, int b);

#ifdef	__cplusplus
}
#endif

//	max.c
//	same as above

//	cppmain.cpp
//	same as above

/*
$ gcc -c max.c
$ g++ -c cppmain.cpp 
$ g++ -o cppmax cppmain.o max.o
$ ./cppmax 
int max = 100
*/

//	cmain.c
#include <stdio.h>
#include "max.h"

int main(void)
{
	int	im	=	max(100, 30);

	printf("int max = %d\n", im);
}

/*
$ gcc -c cmain.c
$ gcc -o cmax cmain.o max.o 
$ ./cmax 
int max = 100
*/