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Srinivasan
C Concepts
1 Answer(s)      3 years and 2 months ago
Posted in : IoC


respected sir, Can I use a void ** pointer as a parameter so that a function can accept a generic pointer by reference?

I have a function

    extern int f(int *);

which accepts a pointer to an int.  How can I pass a constant by
reference?  A call like

    f(&5);

doesn't seem to work.


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June 14, 2011 at 5:16 PM


hi, Srinivasan

In C language you could not write a function which returned generic pointers indirectly via a hypothetical void * pointer because it is not a generic pointer to pointer. You could not passed a void *, but rather a double ** when you will tried to use it for declaring and calling :

double *dptr;
    void *vptr = dptr;
    func(&vptr);
    dptr = vptr;

If the void ** pointer pointed to and is not a void *, and the size and representation of void * is different, then the compiler will unable to access it correctly.

It can not be done directly, for doing this you have to declare a variable temporarily and then the address of it passed to the function

int a = 5;
    f(&a);


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