namespacedemo.cpp

来自「C++&datastructure书籍源码,以前外教提供现在与大家共享」· C++ 代码 · 共 46 行

#include <iostream>

// illustrates using namespaces

namespace Math
{
  int factorial(int n);
  int fibonacci(int n);
}

int Math::factorial(int n)
// post: return n!
{
    int product = 1;
    // invariant: product = (k-1)!
    for(int k=1; k <= n; k++)
    {    product *= k;
    }
    return product;
}

int Math::fibonacci(int n)
// post: return n-th Fibonacci number
{   
    int f = 1;
    int f2= 1;
    // invariant: f = F_(k-1)
    for(int k=1; k <= n; k++)
    {   int newf = f + f2;
        f = f2;
        f2 = newf;
    }
    return f;
}

int main()
{
   int n;
   std::cout << "enter n ";
   std::cin >> n;
   
   std::cout << n << "! = "         << Math::factorial(n) << std::endl;
   std::cout << "F_(" << n << ")= " << Math::fibonacci(n) << std::endl;
   
   return 0;
}