isocpp.org/wiki/faq/mixing-c-and-cpp
[2] Bytes.com
[3] research.att.com
From [3]
------------------------
// C++ code:
extern "C" void f(int);
void f(int i){
// ...
}
/* C code: */
void f(int);
void cc(int i){
f(i);
/* ... */
}
// C++ code:
class C {
// ...
virtual double f(int);
};
extern "C" double call_C_f(C* p, int i) // wrapper function
{
return p->f(i);
}
/* C code: */
double call_C_f(struct C* p, int i);
void ccc(struct C* p, int i){
double d = call_C_f(p,i);
/* ... */
}
// C++ code:
void f(int);
void f(double);
extern "C" void f_i(int i) { f(i); }
extern "C" void f_d(double d) { f(d); }
/* C code: */
void f_i(int);
void f_d(double);
void cccc(int i,double d){
f_i(i);
f_d(d);
/* ... */
}
From [1]
-----------------------------
main.cpp
// This is C++ code
#include "Fred.h"
int main()
{
Fred fred;
c_function(&fred);
}
c-function.c
/* This is C code */
#include "Fred.h"
void c_function(Fred* fred){
unsigned char lc;
cplusplus_callback_function(fred);
lc=Cplusplus_CallbackFunction_Wilma(456,fred);
printf("return of C++ Wilma: %d\n",lc);
}
Fred.cpp
// This is C++ code #include "Fred.h" #include/*std::cout<<*/ //Fred::Fred() : a_(0) { } Fred::Fred() { } void Fred::wilma(int a) { std::cout<<"wilma(arg) print arg "< Fred* cplusplus_callback_function(Fred* fred){ fred->wilma(123); return fred; } //Provide access of C++ methods from C code. unsigned char Cplusplus_CallbackFunction_Wilma(int a, Fred* fred){ fred->wilma(a); return(0); }
Fred.h
/* This header can be read by both C and C++ compilers */
#ifndef FRED_H
#define FRED_H
#ifdef __cplusplus
class Fred {
public:
Fred();
void wilma(int);
private:
int a_;
};
#else
typedef struct Fred Fred;
#endif
#ifdef __cplusplus
extern "C" {
#endif
#if defined(__STDC__) || defined(__cplusplus)
extern void c_function(Fred*); /* ANSI C prototypes */
extern Fred* cplusplus_callback_function(Fred*);
extern unsigned char Cplusplus_CallbackFunction_Wilma(int a, Fred* fred);
#else
extern void c_function(); /* K&R style */
extern Fred* cplusplus_callback_function();
#endif
#ifdef __cplusplus
}
#endif
#endif /*FRED_H*/
Makefile
DESTDIR = ./ PROGRAM = $(DESTDIR)/CCallCplusplus SRCDIR = ./ INCL = -I ./ CP = g++ C = gcc #C = arm-none-linux-gnueabi-g++ OBJS := $(addprefix $(DESTDIR)/,main.o Fred.o c-function.o) DEBUG = -g CFLAGS = -Wall $(DEBUG) all:$(PROGRAM) $(PROGRAM): $(OBJS) $(CP) -o $(PROGRAM) $(OBJS) -lpthread $(DESTDIR)/%.o:$(SRCDIR)/%.cpp $(CP) -c $(CFLAGS) $< -o $@ $(INCL) $(DESTDIR)/%.o:$(SRCDIR)/%.c $(C) -c $(CFLAGS) $< -o $@ $(INCL) clean : rm -f $(OBJS) rm -f $(PROGRAM)
Result:
wilma(arg) print arg 123
wilma(arg) print arg 456
return of C++ Wilma: 0
