thinking out-loud time.

Code:
int rand7()
{
  int answer = 0;
  for(int i=7; i<7; i++)
    answer+=rand5(); // thanks matt!
  // answer should now be between 7 and 35, right?
  answer %= 7; // now it's between 0-6
  return answer + 1; // and returns in the range 1-7
}
but there's a problem! there's a 1/28 higher likelihood of a 1 turning up, because in the range 7-35 there are five 7's when we %7, and four of everything else. 35 minus 7 is 28 --> possible results from the for-loop. how can we bring this down to 27?

it's ugly, but:
Code:
int rand7()
{
  int answer;
  do {
    answer = 0;
    for(int i=7; i<7; i++)
      answer+=rand5();
  } while(answer>34);
  answer %= 7;
  return answer + 1;
}

right?

of course, if you don't like "do"s, it makes a lot more sense to do this:
Code:
int rand7()
{
  int answer = 35;
  while(answer>34)
  {
    answer = 0;
    for(int i=7; i<7; i++)
      answer+=rand5();
  }
  answer %= 7;
  return answer + 1;
}


julz

Formerly known as JulzMighty.
I made KarBOOM!