3.5、3.6 while循环和do……while循环

- 日理万妓 2022-05-20 04:06 164阅读 0赞

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for：for循环重点是是达到指定次数。

while：while循环重点是满足条件即停止循环。

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#include<iostream>
    #include<cstdio>
    using namespace std;
    int main()
    {
    	int n;
    	int maxn = 0, minn = 200, sum = 0;//minn只要设置成比100大的数即可。 
    	cin >> 	n;
    	while(n)//n==0为false，停止while循环 
    	{
    		if(n > maxn) maxn = n;//更新最大值 
    		if(n < minn) minn = n;//更新最小值
    		sum += n;
    		cin >> n;
    	}
    	cout << maxn << " " << minn << " " << sum << endl;
    	return 0;
    }

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#include<iostream>
    #include<cstdio>
    //#define EPS 0.001
    double EPS = 0.001; 
    using namespace std;
    int main()
    {
    	double a;
    	cin >> a;
    	if(a >= 0)
    	{
    		double x1 = a/2, lastx = x1 + 1 + EPS;//lastx表示前一次的x，只要比x1大EPS即可  初始数据 
    		while ((x1 - lastx) > EPS || (lastx - x1) > EPS)//绝对值小于EPS终止循环  迭代条件 
    		{
    			lastx = x1;
    			x1 = (x1 + a/x1) / 2;
    		}
    		cout << x1 << endl;
    	}
    	else 
    		cout << "It's can't be nagitive." << endl;
    	return 0;
    }

【迭代公式写代码】

第一步： 先写初始的迭代数据；

第二步： 用while循环进行迭代。

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【重点】语句组至少要执行一次。

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#include<iostream>
    using namespace std;
    int main()
    {
    	int n = 1;
    	do
    	{
    		cout << n << " ";
    		n *= 2;
    	} while (n < 10000);
    	return 0; 
    }

#include<iostream>
    using namespace std;
    int main()
    {
    	int n = 1;
    	while (n < 10000)
    	{
    		cout << n << " ";
    		n *= 2;
    	}
    	return 0;
    }

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