Problem receiving an array as pointer parameter-CodePudding

Hi I have a trouble trying to manage a the following array. I have initialized this pointer int* coordenadasFicha = new int[2]; and I want to asign the two int asking the user for the numbers. The trouble appears when I call pedirCoordenadasFicha(coordenadasFicha); Clion recomends me cast coordenadasFicha to int** but I need to use it as a simple pointer. pedirCoordenadasFicha() basically does this:

void pedirCoordenadasFicha(int* coordenadasFicha[2]){
    std::cin >> *coordenadasFicha[0];
    std::cin >> *coordenadasFicha[1];}

All help is welcome

CodePudding user response：

An int* (a pointer-to-int) and an int*[] (an array of pointer-to-int) are two different things. And actually, in a function parameter, int* coordenadasFicha[2] is actually passed as int** (pointer to pointer-to-int), because an array decays into a pointer to its 1st element.

In your case, you are creating coordenadasFicha as an dynamic array of ints, but your function is expecting an array of int* pointers instead.

So, to do what you are attempting, you would need to do either this:

void pedirCoordenadasFicha(int* coordenadasFicha){
    std::cin >> coordenadasFicha[0];
    std::cin >> coordenadasFicha[1];
}

int* coordenadasFicha = new int[2];
pedirCoordenadasFicha(coordenadasFicha);
...
delete[] coordenadasFicha;

Or this:

void pedirCoordenadasFicha(int* coordenadasFicha[2]){
    std::cin >> *coordenadasFicha[0];
    std::cin >> *coordenadasFicha[1];
}

int** coordenadasFicha = new int*[2];
for(int i = 0; i < 2;   i) {
    coordenadasFicha[i] = new int;
}
pedirCoordenadasFicha(coordenadasFicha);
...
for(int i = 0; i < 2;   i) {
    delete coordenadasFicha;
}
delete[] coordenadasFicha;

Or, just get rid of new altogether, and pass the array by reference:

void pedirCoordenadasFicha(int (&coordenadasFicha)[2]){
    std::cin >> coordenadasFicha[0];
    std::cin >> coordenadasFicha[1];
}

int coordenadasFicha[2];
pedirCoordenadasFicha(coordenadasFicha);
...

CodePudding user response：

I need to use it as a simple pointer.

int* coordenadasFicha[2] is not a "simple pointer", if by simple pointer you mean int*. In any other context, coordenadasFicha would be an array of pointers, but function parameters aren't arrays in C ; the parameter is adjusted to be a pointer to element of such array. The element of the array is int* and a pointer to int* is int**. Hence the type of coordenadasFicha is int** (after adjustment).

If you want a parameter to have the type int*, then you must declare the parameter to have the type int* and not some other type. Example:

void
pedirCoordenadasFicha(int* coordenadasFicha)
{
    std::cin >> coordenadasFicha[0];
    std::cin >> coordenadasFicha[1];
}