/* Code for exercise 7.18. |  | "C++ Solutions--Companion to The C++ Programming Language, Third Edition" | by David Vandevoorde; Addison-Wesley 1998; ISBN 0-201-30965-3. | | Permission to use, copy, modify, distribute and sell this software | and its documentation for any purpose is hereby granted without fee. | The author makes no representations about the suitability of this | software for any purpose.  It is provided "as is" without express or | implied warranty. `----------------------------------------------------------------------*/#include <stdio.h>#include <string>#include <stdexcept>int factorial(int a) {   if (a<0) throw std::domain_error(std::string("negative factorial"));   int result = 1;   while (a>1)      result *= a--;   return result;}int main() {   printf("7! = %d\n", factorial(7));   return 0;}