迭代或递归因子 [英] Iterative or Recursive Factorial

问题描述

嗨


我用递归的方式实现了阶乘：

 < span class =code-keyword> int  factorial（ int  x）{
  if （x< =  0 ）
  return   1 ; 
  else  
  return （x * factorial（x  -   1 ））; 
} 
 
  int  _tmain（ int  argc，_TCHAR * argv []）
 {
 std :: cout<<  请输入您的号码:::; 
  int  x; 
 std :: cin>> X; 
 std :: cout<<   factorial（<< x< <  ）=<<阶乘（X）; 
 getchar（）;的getchar（）; 
} 

实现此类代码的哪种方式更有用，使用迭代和循环编写它或者递归写入如上所述？

解决方案

在这种情况下最好使用迭代/循环。

详情请访问：

http： //www.informit.com/articles/article.aspx?p=1874865 [ ^ ]



谢谢。

这取决于你的理解通过最好的。它是最快，最容易理解的代码，最优雅，最容易维护等等吗？



如果你必须将其作为库函数实现，速度显然会发挥作用一个重要的角色。那肯定会让你在循环中实现它。递归实现要慢得多，因为每次乘法也会占用过程调用的时间。所以大多数人会说迭代实现是最好的。如果你要编写一个编程类并希望演示递归函数的概念，你的目标可能会有所不同。

你是对的，在这种情况下，递归是最好和最干净的。 / BLOCKQUOTE>

Hi
I've implemented factorial recursively this way:

int factorial(int x){
	if (x <= 0)
		return 1;
	else
		return (x*factorial(x - 1));
}

int _tmain(int argc, _TCHAR* argv[])
{
	std::cout << "Please enter your number :::";
	int x;
	std::cin >> x;
	std::cout<<"factorial(" << x << ") = "<< factorial(x);
	getchar(); getchar();
}

which way of implementing such code is more useful writing it using iteration and loops or writing it recursively such as above?

解决方案

It is better to use Iterations/loops in this case.
For details explanation please visit:
http://www.informit.com/articles/article.aspx?p=1874865[^]

Thanks.

It depends on what you understand by "best". Is it fastest, easiest code to comprehend, most elegant, easiest to maintain, etc.?

If you had to implement it as a library function the speed would obviously play a big role. And that would certainly have you implement it in a loop. A recursive implementation is much slower, because each multiplication does also consume the time of a procedure call. So most people will say that the iterative implementation is the "best". If you were to give a programming class and wanted to demonstrate the concept of recursive functions your goal could be different, though.

You are correct, in this case recursion is best and cleanest.

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