C++ only knows the length of a char array by itself, so your class constructor would need a pointer to the array instead, and a second parameter for the size of the array. Your constructor will need a lot of changes to work properly.
First, your array must be allocated by new:
Code:
int foo_array = new int[foo_size];
Then you must loop through the array you want stored, using the pointer passed in to fill the class' array.
Code:
for(int i(0); i < foo_size; i++) {
foo_array[i] = array_in[i];
}
Your destructor must call delete on the foo_array:
Code:
delete[] foo_array;
Your problem is also best solved, I think, by simply containing a vector as a member. Since I am assuming you don't know what vectors are, you will need to learn. The sooner you do that, the better.