calculate the sum of diagonals in a matrix

Question

I need to calculate the sum of two diagonals in a matrix in C++, I already have a solution for that but I must be dumb because I cant understand what it is doing, so I would

Answer 1

int diag1=0;
int diag2=0;

for (i=0;i

}

To understand this algorithm better you should paint a matrix on you notebook and number it's elements with their position in matrix,then apply the algorithm step by step.I'm 100% sure that you will understand