C++ and recursion with arrays - c++

Question

I've programmed with other languages, but now that I am learning C++, I've found a problem. I am trying to solve a problem with recursion, with a method that takes an array as an argument. I thought about using a public array, maybe, but I can't use the array either way.
From what I've read, it seems to me that it has something to do with the memory. (I thought that, even though it consumes a lot of memory, creating it again with each call would work.)
Here's some code:
static void FindSolution(int row, int column, bool answer[][8][8]) {
for(int i = 0; i < 8; i++)
//Some processing…
bool temp = true;
FindSolution(0, column + 1, answer[row][column] = temp);
}
}
How do I get to actually use the array? Somehow.
The error:
error: array type 'bool [8]' is not assignable
FindSolution(0, column + 1, answer[row][column] = temp);

Answer 1

You have an extra [] on your array. You've declared it as a 3D array, but then you try to assign to it like it is a 2D array. The compiler gets upset because you try to assign a bool value to an array, which is exactly what you are doing:
answer[row][column] = temp;
temp has type bool, but answer[row][column] has type bool[8].
Instead declare the argument without the extra []:
static void FindSolution(int row, int column, bool answer[8][8]) {

Answer 2

You keep incrementing 'column', but you never check it to make sure it doesn't reach 8. When it does reach 8, you're off the end of the array, and you get an error.

Answer 3

There are a few immediate problems with this.
First Problem: Function signature is incorrect
You've declared the third parameter as a 3-dimensional array, but you only want to deal with two dimensions it seems. There are a couple of ways you can redeclare this function to accept a 2D array, for all the options see the accepted answer here. Personally, in this situation I'd go with a template option unless there is a specific reason not to. Something like the following:
template<size_t _rows, size_t _columns>
static void FindSolution(int row, int column, bool (&answer)[_rows][_columns]) {
// todo: Some processing...
}
This allows you to accurately know the size of the array at compile time, of course this won't work so well with dynamically allocated arrays but seeing as you seemed to know the dimensions of the array already at compile time, I figured this wasn't an issue. If it is, check the other ways of passing a 2D array to a function in the link I attached.
Second issue: Recursive call
The second issue is how you're doing your recursive call.
FindSolution(0, column + 1, answer[row][column] = temp);
The result of the assignation of temp to the specific location in the answer array is not the answer array, but rather the value of temp. Effectively the following statement:
answer[row][column] = temp
Is trying to pass a single bool value as a 2-dimensional array, which won't work. In order to correctly call the method again you'll need to do your assignation of temp to the answer array, then call the function again.
answer[row][column] = temp;
FindSolution<_rows,_columns>(0, column + 1, answer);
Should work fine. (Note the explicit template arguments here <_rows,_columns>, this is only needed if you're using the function signature I posted above which made use of templates)