Function intPow

src/3rdparty/QXlsx/source/xlsxcellreference.cpp:13–21

namespace {

int intPow(int x, int p)
{
  if (p == 0) return 1;
  if (p == 1) return x;

  int tmp = intPow(x, p/2);
  if (p%2 == 0) return tmp * tmp;
  else return x * tmp * tmp;
}

QString col_to_name(int col_num)
{