4elist0715.cpp

《21天学通C＋＋》附盘的原代码。书上的每个例子在这里都有相应的C语言程序。

// Listing 7.15
// Demonstrates solving the nth
// Fibonacci number using iteration

#include <iostream>

int fib(int position);
int main()
{
	using namespace std;
	int answer, position;
	cout << "Which position? ";
	cin >> position;
	cout << "\n";

	answer = fib(position);
	cout << answer << " is the ";
	cout << position << "th Fibonacci number.\n";
	return 0;
}

int fib(int n)
{
	int minusTwo=1, minusOne=1, answer=2;

	if (n < 3)
		return 1;

	for (n -= 3; n; n--)
	{
		minusTwo = minusOne;
		minusOne = answer;
		answer = minusOne + minusTwo;
	}

	return answer;
}