2 Dimensional Vectors

[coolbeanbob]

Hello,

I am trying to add integers to a two dimensional vector.

My problem is on line 26. I know this is how you would add the data to an array, but how do you do this for a vector?

Also, is it true you cannot pass an array to a function as a parameter?

int main()
{
	const short s = 10;
	const short r = 10000;
	const string fileName = "Lab9.txt";

	vector< vector<short> > matrix;
	//short matrix[s][r];

	// Open the data file
    ifstream fin(fileName.c_str());
    if (!fin.is_open()) 
	{
        cout << endl << "Unable to open input file " << fileName << endl;
        return 1;
    }// End if (!fin.is_open())


	// Fill up matrix
	int temp = 0;
	for(int t = 0; t < s ; t++)
	{
		for(int i = 0; i < r; i++)
		{
				fin >> temp;
				matrix[t][i].push_back(temp);
		}// End for(int i = 0; i < r; i++)
	}// End for(int t = 0; t < s ; t++)

	//insertion_sort(matrix);

	cout << matrix[0][9] << endl;

The file compiles when I remove the [t], but I need to keep track of t, because I am trying to create a 10x10000 matrix.

matrix[i].push_back(temp);

[VernonDozier]

Seems like you should remove the i, not the t. For a 2-D array, I assume you are doing this...

matrix[t][i] = temp;

and you want to convert that code. You can either add an element to a vector or change an element that you already have. In your case, since you are using push_back on a 2-D vector, you'll use ONE, not TWO [] operators, so it's going to be this...

matrix[t].push_back(temp);

Unlike arrays, you don't need i. You don't need to tell the vector where to put the element. An array doesn't know where the "end" is, but a vector does.

On the other hand, if you know ahead of time what your vector sizes should be, don't use push_back. Instead, set their capacities using "resize" or "reserve" and then set the elements as you would in an array...

matrix[t][i] = temp;