Question

Having some trouble finding the sum of a 2D vector. Does this look ok?

int sumOfElements(vector<iniMatrix> &theBlocks)
{
  int theSum = 0;

  for(unsigned i=0; (i < theBlocks.size()); i++)
  { 
    for(unsigned j=0; (j < theBlocks[i].size()); j++)
    {
        theSum +=theBlocks[i][j];
    }
  }

  return theSum;
}

It returns a negative number, however, it should return a positive number..

Hope someone can help 🙂

Answer 1

The code looks proper in an abstract sense, but you may be overflowing theSum. You can try making theSum type double to see what value you get to help sort out the proper integral type to use for it.

double sumOfElements(vector<iniMatrix> &theBlocks)
{
  double theSum = 0;
  /* ... */
  return theSum;
}

When you observe the returned value, you can see if it would fit in an int or if you need to use a wider long or long long type.

If all the values in the matrix are positive, you should consider using one of the unsigned integral types. which would double your range of allowed values.