How to pass a 3D array as a parameter to function C++? Also Do global variables need to be passed into functions?

Question

So I have several questions. First how do I pass a 3D array into a function. I need to pass the whole array as the function is to run a loop to output the contents of the array to a file. This is what I currently have

int array[5][3][3]
void function(int a[5][3][3])
{
//...
}
void function(array); //or void function(array[5][3][3]);

I have found a way to make it work using pointers to the array, however I have asked my teacher and he does not want us to use pointers.

My second question is if I plan to modify a global variable inside a function, I do not need to pass it to the function? I can just use it inside the function as I would inside main?

Yet another problem I am having now is passing a single value from an array into a function.

In a loop I need to pull a value from an array[i][j][2] (i and j being indexes of an outer and inner loop) and pass it to a function to evaluate whether or not it is greater than 90. This is for a school assignment, so understand there are certain specifications I have to meet. (Like not using pointers, and passing a whole array, and passing one value from an array, because as a class we have not yet learned how to use pointers)

Answer 1

Your code is correct, but actually there no such thing as an array parameter in C++ (or in C). Silently the compiler will convert your code to the equivalent pointer type, which is

int array[5][3][3];

void function(int (*a)[3][3])
{
    ...
}

So although your professor told you not to use pointers, actually you cannot avoid them, because there's really no such thing as an array type parameter in C++.

Second question, the only point of globals is that you can refer to them anywhere, so no need to pass them as parameters.

Answer 2

For passing complex arrays I prefer to wrap them in a structure:

struct array {
    int a[5][3][3];
};

void function(struct array *a) ...

This avoids a lot of pitfalls with trying to pass arrays as function arguments.