Explicit cast in C [closed]

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I want to convert pointers of any type to int in C and C++. The code must be the same for both C a开发者_如何学Pythonnd C++. The following program works for C but not for C++.

int main(void)
{
    long long a;
    int b = (int)&a;

    return 0;
}

How can I get it working for C++?

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Looks like you want the offsetof macro, it's defined in <stddef.h>.

Edit: You have changed your example, now you should look at intptr_t or uintptr_t which are in stdint.h. Do not, under any circumstances, put an address into a plain int.

---

Did you mean:

struct X
{
        char a;
        long long b;
};

int main(void)
{
        int b[20];
        // C++ requires fixed size of arrays.

        b[(int)(&((struct X*)0)->b) - 8] = 5;
        // This will compile But what you get is not even worth guessing at.

        return 0;
}