Question

I have a question which involves calling a function with 2 parameters of a pointer to a pointer

int main(void)
{ ...
int *ptrp = &p, *ptrq = &q;
int **ppp = &ptrp, **ppq  = &ptrq;
swap_ptr(ppp,ppq);/* &ptrp, &ptrq passed */ 
/* to swap_ptr() */
return 0;
}

void swap_ptr(int **ptrA,int **ptrB)...

We have to swap the values of ptrp and ptrq, so does that mean in the swap_ptr function I just use *ptrA and *ptrB to swap them or is it some other pointer statement?

Thanks

Answer 1

Yes, *ptrA would refer to the variable ptrp in main and *ptrA would refer to ptrq. Swap these two values as you would for any other type and ptrp will now point to q and ptrq to p.

Since this sounds like it might be homework I’ll let you come up with the three lines of code.