Calculate Primary and Secondary Diagonal

int sum=0;
For (int i=0;i<Line;i++)
    For(int j=0;j<COL;j++)
    {
         //Primary diagonal
         if(i==j )sum += A[i][j];
         //Secondary diagonal
         if(i==(COL-j))sum += A[i][j];
     }

Assuming the matrix size is row, col and i represents the row and j represents the col. Get the primary Diagonal where i==j and secondary diagonal where i==j-1. Below is the code for that.

Code
for (int i = 0; i < row; i++)
            {
                int j = 0;
                while (j < col)
                {
                    //Primary diagonal
                    if (i == j) sum += A[i][j];
                    j++;
                    //Secondary diagonal
                    if (i == (col - j)) sum += A[i][j - 1];
                }
            }