Hi guys

Is there a way to make a function pointer to point to different function?? For example:

// function pointer to a function with no return and no parameter
typedef void (* func_1) (void);

// function pointer to a function with int return, and int parameter
type int (*func_2)(int);

Is there a way to make a function pointer that can point to both?

// some kind of function pointer that can point to both
typedef [NULL??] (*func_all)(NULL??);

func_all func_void;
func_all func_int;

func_void = func_1;
func_int = func_2;

Thanks guys!

 

Use a pointer array... each element can point to a different function... Menu systems sometimes use this method... As to your other question.. OpenRTOS has available C code...

 

This might be useful -

https://www.geeksforgeeks.org/function-pointer-in-c/


Regards,. Dana.

 

Hi guys

Is there a way to make a function pointer to point to different function?? For example:

// function pointer to a function with no return and no parameter
typedef void (* func_1) (void);

// function pointer to a function with int return, and int parameter
type int (*func_2)(int);

Is there a way to make a function pointer that can point to both?

// some kind of function pointer that can point to both
typedef [NULL??] (*func_all)(NULL??);

func_all func_void;
func_all func_int;

func_void = func_1;
func_int = func_2;

Thanks guys!

The short answer is no. Function overloading is not a feature of C.
1. Recode in C++
2. Have a read if this https://stackoverflow.com/questions/2873850/is-there-an-equivalent-in-c-for-c-templates. It offers some workarounds for C, but they are pretty ugly.

 

This is a bad idea, type checking is one of the few things in C that can help save you from silly errors. That said; with casting you can do pretty much whatever you want. Such as:

typedef void(*funcPtr) (void* funcParam);

void myIntFunc(void* x)
{
    // First cast the data ty pe
    int* pMyVar = (int*)x;
    printf("My int func: %i\n\n", *pMyVar);
}

void myVoidFunc(void* x)
{
    printf("My void func\n\n");
}

void myStringFunc(void* x)
{
    // Cast to get our data
    char* pStr = (char*)x;
    printf("myStringFunc: %s\n\n", pStr);

}


int main()
{
    funcPtr myFunc = (funcPtr)(&myVoidFunc);
    myFunc(NULL);
  
    int myInt = 10;
    myFunc = (funcPtr)(&myIntFunc);
    myFunc(&myInt);

    char myStr[] = "Hello world!";
    myFunc = (funcPtr)(&myStringFunc);
    myFunc(myStr);
  
}

 

This is a bad idea, type checking is one of the few things in C that can help save you from silly errors. That said; with casting you can do pretty much whatever you want. Such as:

typedef void(*funcPtr) (void* funcParam);

void myIntFunc(void* x)
{
    // First cast the data ty pe
    int* pMyVar = (int*)x;
    printf("My int func: %i\n\n", *pMyVar);
}

void myVoidFunc(void* x)
{
    printf("My void func\n\n");
}

void myStringFunc(void* x)
{
    // Cast to get our data
    char* pStr = (char*)x;
    printf("myStringFunc: %s\n\n", pStr);

}


int main()
{
    funcPtr myFunc = (funcPtr)(&myVoidFunc);
    myFunc(NULL);
 
    int myInt = 10;
    myFunc = (funcPtr)(&myIntFunc);
    myFunc(&myInt);

    char myStr[] = "Hello world!";
    myFunc = (funcPtr)(&myStringFunc);
    myFunc(myStr);
 
}

View attachment 172645

I can see this is a bad idea, at the same time I think it’s also quite cool. You can do a lot with void pointer.

 

Yes! But its no different to just calling three different functions.. All this is good stuff, but the idea is you call a function depending on an event.
So a switch statement or an array will still have several functions... Even with the automation of C++ with overloading, there are separate functions.... bug13 asked if you could make a function pointer point to different functions... The answer is Yes but one function at a time using any of the above answers.. A single pointer can only point to one location at a time.. You will still need to decipher which to point to..