Passing a 2D array to a C++ function

Question

I have a function which I want to take, as a parameter, a 2D array of variable size.

So far I have this:

void myFunction(double** myArray){
     myArray[x][y] = 5;
     etc...
}

And I have declared an array elsewhere in my code:

double anArray[10][10];

However, calling myFunction(anArray) gives me an error.

I do not want to copy the array when I pass it in. Any changes made in myFunction should alter the state of anArray. If I understand correctly, I only want to pass in as an argument a pointer to a 2D array. The function needs to accept arrays of different sizes also. So for example, [10][10] and [5][5]. How can I do this?

Answer 1

There are three ways to pass a 2D array to a function:

1. The parameter is a 2D array

   int array[10][10];
   void passFunc(int a[][10])
   {
       // ...
   }
   passFunc(array);
   

2. The parameter is an array containing pointers

   int *array[10];
   for(int i = 0; i < 10; i++)
       array[i] = new int[10];
   void passFunc(int *a[10]) //Array containing pointers
   {
       // ...
   }
   passFunc(array);
   

3. The parameter is a pointer to a pointer

   int **array;
   array = new int *[10];
   for(int i = 0; i <10; i++)
       array[i] = new int[10];
   void passFunc(int **a)
   {
       // ...
   }
   passFunc(array);