question about function pointer compile error

[dragondad]

---

I have a program which was coded by mix of c++ and c code, when I test the function pointer in C code, it is ok, but when I try to merge it with C++ code, it give me compile error like this:

gcc -g -Wall -D_GNU_SOURCE -DDEBUG -c wmain.cpp
wmain.cpp:42: invalid conversion from `void*(*)(void*)' to `void (*)(void*)'
wmain.cpp:42: invalid conversion from `void*(*)(void*)' to `void (*)(void*)'
wmain.cpp:42: invalid conversion from `void*(*)(void*)' to `void (*)(void*)'
wmain.cpp: In function `int main(int, char**)':
wmain.cpp:97: invalid conversion from `void (*)(void*)' to `void*(*)(void*)'
gmake: *** [wmain.o] Error 1

Here it is the snapshot of my two files (one is the header file to define the function pointer)

In threadhandler.h

#ifdef __cplusplus
extern "C" {
#endif

......

#define MSG1 1
#define MSG2 2
#define MSG3 3


extern void *PrintHello1(void *params);
extern void *PrintHello2(void *params);
extern void *PrintHello3(void *params);

typedef void (*Func)(void *);

struct PrintHi {
int msg;
Func funcptr;
};

#ifdef __cplusplus
}
#endif

In wmain.cpp

......

struct PrintHi PrintHiTable[3] = {
{ MSG1, PrintHello1 },
{ MSG2, PrintHello2 },
{ MSG3, PrintHello3 }
}; // here it is the LINE 42

int main(int argc, char *argv[])
{

......

for (i=0; i< NUM_THREADS; i++) {

......

pthread_create(&threads[i], NULL, PrintHiTable[i].funcptr, (void *) &thread_data_array[i]); // here it is the LINE 97

}

}

Please let me know if you have any good solution.
Thanks.

[Roxoff]

Shouldn't you be using:

typedef void Func(void *);

struct PrintHi { 
int msg; 
Func* funcptr; 
};

Unless your functions really do return a void*, in which case you should set your typedef to 'void* Func(void*);'

[Workaphobia]

 invalid conversion from `void*(*)(void*)' to `void (*)(void*)'

In C you can convert implicitly from a void pointer to any other pointer, but it suprises me that it would allow you to also convert to void itself. C++ forbids this.

extern void *PrintHello1(void *params); 
extern void *PrintHello2(void *params); 
extern void *PrintHello3(void *params); 
 
typedef void (*Func)(void *);

You defined the function as returning a void pointer by including an asterisk before PrintHello. An asterisk can only be used to create a function pointer when there are parenthesis to group it with the function name - you don't need to do that there since on those lines you want to make prototypes and not pointers. The typedef line looks fine.