c++ - 在c++中找到用户输入的3个最大数字的平均值

Question

所以设计问题是:

输入3个数字，显示最大的。继续输入 3 个数字组，直到用户想要退出。求出所有最大数字的平均值。

所以输入数字工作正常，但是当我尝试插入 SENTINEL 值以停止循环时，我需要为所有 3 个数字输入它，但它没有给我一个正确的平均值对于过去输入的数字。

非常感谢您抽出宝贵时间提供任何帮助!

 #include <iostream>
 using namespace std;

int main()
{

    const int SENTINEL = -1;
    int num1;
    int num2 = 0;
    int num3 = 0;
    int largest;
    int sum;
    int count;
    float average;

    // initialize the count and sum
    count = 0;
    sum = 0;

    while (num1 != SENTINEL)
    {

        // Prompt user for the first number or to quit
        cout << "If you want to quit enter " << SENTINEL << " to stop\n " << endl;
        cout << "Enter first number  ";
        cin >> num1;

        // Prompt the user for the second number
        cout << "please enter second number                  ";
        cin >> num2;

        // Prompt the user for a third number
        cout << "please enter the third number               ";
        cin >> num3;

        // Compare numbers 1 and 2 for the largest number
        if (num1 > num2)
        {
            largest = num1;
        }
        else
        {
            largest = num2;
        }

        // Compare largest to last number input
        if (num3 > largest)
        {
            largest = num3;
        }

        // Display the largest number
        cout << "largest number is: " << largest << endl;

        // Increment the count
        count++;

    }



    if (count > 0)
    {
        average = sum / count;
        cout << "Average of the numbers is " << average;
    }

    return 0;
}

Answer 1

使用 break; 指令是一种可能，但通常被认为不够优雅且难以维护。

原因是你打破了代码流，你的程序的读者(在大程序中可能不是你，或者如果你分享它)希望你的循环代码继续到它的结尾.如果您的函数有一个或多个 break; 指令，则可能很难理解该函数的意图，因为您必须记住在哪些情况下循环已经结束。

解决问题的基本原则是在正确的位置开始循环，就在获得 num1 的值之后。然后你的循环也必须以它结束。这样，您将始终在用户键入 num1 后立即检查退出条件。

// initialize the count and sum
count = 0;
sum = 0;

// Prompt user for the first number or to quit
cout << "If you want to quit enter " << SENTINEL << " to stop\n " << endl;
cout << "Enter first number  ";
cin >> num1;

while (num1 != SENTINEL)
{

    // Prompt the user for the second number
    cout << "please enter second number                  ";
    cin >> num2;

    // Prompt the user for a third number
    cout << "please enter the third number               ";
    cin >> num3;

    // Compare numbers 1 and 2 for the largest number
    if (num1 > num2)
    {
        largest = num1;
    }
    else
    {
        largest = num2;
    }

    // Compare largest to last number input
    if (num3 > largest)
    {
        largest = num3;
    }

    // Display the largest number
    cout << "largest number is: " << largest << endl;

    // Increment the count
    count++;

    // Prompt user for the first number or to quit
    cout << "If you want to quit enter " << SENTINEL << " to stop\n " << endl;
    cout << "Enter first number  ";
    cin >> num1;
}

if (count > 0)
{
    average = sum / count;
    cout << "Average of the numbers is " << average;
}

return 0;

注意:我这里没有解决代码错误，如评论中提到的(变量未声明，总和未更新等)。