Example

Example: validation algorithm

In this example, the license key consists of two values, where the faculty of the first value has to be equal to the second value to be a regular license key. The following check-function will be used to validate the license key:
 

bool check(int key_part1, int key_part2)
{
  if(fun(key_part1)==key_part2)
    return true;
  return false;
}

int fun(int key)
{
  int a=1;
  if (key<1)
    a=1;
  else
    do{
      a *= key--;
    }while (key>1);
  return a;
}