c++ - 在 C++ 中查找用户输入的最小值

Question

我的问题是从用户定义的输入数量中找出最小值。到目前为止一切都很好，除了那个。每次我尝试重新排列一些代码或尝试一种新方法时，我总是在屏幕上得到相同的输出:

Sum of numbers entered is:      145.4
Average of numbers entered is:  24.2333
The Highest number entered was: 45
The Lowest number entered was:  6.95283e-310

我每次都会得到这个，不管输入的是什么，或者我尝试过什么不同的建议:

The Lowest number entered was:  6.95283e-310

我知道数组的使用和实现。但是，我正在做的作业甚至还没有涵盖数组。那是后面的一些章节。请不要建议数组...

我看过这里:

Finding Maximum and Minimum values in c++ by user input没用

http://www.cplusplus.com/forum/beginner/38799/没用

改变最大/最小值也不起作用

#include <iostream>
using namespace std;

int main() 
{

    double number, numberitems, sum = 0, average, max, min;

    cout << "Enter number of items: \n";
    cin >> numberitems;

    //Make sure user can not enter negatives
    if ( numberitems < 0 ) {
        //no request to perform sum
        std::cout << "I said not to enter a negative number... '\n";
        std::cin.clear(); //clear bad input flag
        return 1;
    }

    //Get the user's values
    for (int i = 0; i < numberitems; i++)
    {
        std::cout << "Enter any NON-negative number: ";
        std::cin >> number; 
        std::cout << '\n';


        //Maximum value entered
        if (number > max) {
            max = number;
        }

        //minimum value entered
        if (number < min) {
            min = number;
        }

        //Make sure user can not enter negatives
        if ( number < 0 ) {
            //no request to perform sum
            std::cout << "I said not to enter a negative number... '\n";
            std::cin.clear(); //clear bad input flag
            return 1;
        }

        //Sum of all the numbers
        sum = sum + number;

        //Average of all the numbers
        average = sum / numberitems;


    }
    std::cout << endl;
    std::cout << endl;
    std::cout << "Sum of numbers entered is:      " << sum << '\n';
    std::cout << "Average of numbers entered is:  " << average <<'\n';
    std::cout << "The Highest number entered was: " << max <<'\n';
    std::cout << "The Lowest number entered was:  " << min <<'\n';
    return 0;
}

临时修复 :3

    double min = 99999999999999999999999999999999999999999999999;

我对此很陌生。

已更新

阅读更多评论后，我发现我不见了 <cfloat> .使用 #include <cfloat>现在上面每个人的建议都有效。然而，<cfloat>根本没有上课。所以我不确定这在这里是否可用？

#include <iostream>
#include <cfloat>
using namespace std;

int main()
{

    int numberitems;
    double number, sum = 0, average;
    double max = 0;
    double min = DBL_MAX;

    cout << "Enter number of items: \n";
    cin >> numberitems;

    //Make sure user can not enter negatives
    if ( numberitems < 0 ) {
        //no request to perform sum
        std::cout << "I said not to enter a negative number... '\n";
        std::cin.clear(); //clear bad input flag
        return 1;
    }

    //Get the user's values
    for (int i = 0; i < numberitems; i++)
    {
        std::cout << "Enter any NON-negative number: ";
        std::cin >> number;
        std::cout << '\n';


       //Maximum value entered
      if (number >= max) {
            max = number;
          }

       //minimum value entered
       if (number <= min) {
            min = number;
        }

       //Make sure user can not enter negatives
       if ( number < 0 ) {
            std::cout << "I said not to enter a negative number...'\n";
            std::cin.clear(); //clear bad input flag
            return 1;
        }

       //Sum of all the numbers
       sum = sum + number;

       //Average of all the numbers
       average = sum / numberitems;

    }

    //Print the results
    // some cosmetic...
    std::cout << endl;
    std::cout << endl;
    std::cout << "\n=================REPORT====================\n";
    std::cout << '\n';
    std::cout << "\tYour Totals\tValues\n";
    std::cout << "\t-----------\t------\n";

    std::cout << "\t    Sum:        " << sum << '\n';
    std::cout << "\t  Average:      " << average <<'\n';
    std::cout << "\t  Highest:      " << max <<'\n';
    std::cout << "\t   Lowest:      " << min <<'\n';
    return 0;
}

再次，<cfloat>工作正常，但我不确定是否允许我使用它。还有哪些其他解决方法？

Answer 1

问题已经有了很好的答案 - 很快:min 和 ma​​x 未初始化。

然而

上面说的很具体。当然，它在这种特定情况下会有所帮助，但我觉得在这里和许多其他情况下都需要更广泛的建议。

添加打印输出

在这种情况下，向您的代码添加调试打印输出(“不使用调试器进行调试”)总是有帮助的。

例如，在您的示例中添加以下内容可能会有所帮助:

//Get the user's values
for (int i = 0; i < numberitems; i++)
{
    std::cout << "Enter any NON-negative number: ";
    std::cin >> number; 
    std::cout << '\n';


    //Maximum value entered
    if (number > max) {
        // debug - (remove before submission)
        std::cout << "number is the new max! number = " << number
                  << ", max = " << max << std::endl;
        // end of debug
        max = number;
    }

    //minimum value entered
    if (number < min) {
        // (debug - remove before submission)
        std::cout << "number is the new min! number = " << number 
                  << ", min = " << min << std::endl;
        // end of debug
        min = number;
    }