what does null function pointer in C mean?

Question

Say we have a function pointer:

void (*func0)(void);

which is also defined:

void func0(void) { printf( \"0\\n\" ); }
         


        

Answer 1

It is undefined behaviour to de-reference a null pointer. The fix is simply to ensure that the pointer refers to an appropriate function.

In your case you want something like this:

void MyFunction(void)
{
    printf( "0\n" ); 
}

and then later you can assign to func0:

func0 = &MyFunction;

Note that I am using a different name for the function pointer variable and the actual function.

And now you can call the function, via the function pointer:

func0();