How cache memory works?

Question

Today when I was in computer organization class, teacher talked about something interesting to me. When it comes to talk about Why cache memory works, he said that:

Answer 1

In C, n-dimensional matrices are row major, meaning the last index into the matrix represents adjacent spaces in memory. This is different than some other languages, FORTRAN for example, which are column major. In FORTRAN, it's more efficient to iterate through a 2D matrix like this:

do jj = 1,N
  do ii = 1,M
    x(ii,jj) = x(ii,jj) + K;
  enddo
enddo