std::vector<std::vector<unsigned long> > matrix(15); // 15 rows
typedef std::vector<std::vector<unsigned long> >::iterator it_type;

it_type row = matrix.begin();

for (int w=0;w<10;w++)
{
//some lines of code
unsigned long num = x.to_ulong(); 
cout <<"Decimal form is: " << num<< end;
// if we've hit 15 items in the current row (i.e. 15 columns), then shift to the next row
if (row->size() == 15)
++row;

// add this to the next column in the current row
row->push_back(num);
}
// resize the last row
row->resize(15); // this will ensure that there are 15 columns in the last row


for(size_t i=0; i < matrix.size(); ++i)
{
for(size_t j=0; j < matrix[i].size(); ++j)
cout << matrix[i][j] << " ";
cout << endl;
}

Now I want to find maximum, minimum and average of this matrix. What shall I do?

Go through each element and keep track of the minimum and maximum values as you go. Also, add the element to a running sum and at the end divide by the number of elements.

Go through each element and keep track of the minimum and maximum values as you go. Also, add the element to a running sum and at the end divide by the number of elements.

Load the first value of the matrix into your min and max variables first. That gives you the first 'guess' at the answer. After all, it could be...