Create and compile a simple program:
#include <iostream>
int main(){
      int i=0;
      i = 6+ i++ + 2000;
      std::cout << i << std::endl;
      return 0;
}

when running, it results "1" even when it should result "2006". If I remove the 
postfix operation "i++" the result is correct("2006"). As long as I keep 
that "i++" inside the equation I can divide, multiply, substract or add what 
ever I like, and the result is allways "1". ( There is exeption: Dividing with 
zero, creates warning and the result program craches like it should do. )

example: If the equation is
i = (6+ i++ + 2000)/2;
then "i" is still the same 1.

If I replace the postfix "i++" with prefix "++i" then the equation is 
calculated correctly, but the meaning is different( as you know prefix and 
postfix adding have different behaviour)).