c++ - Stroustrup C++ 书籍。如何跟踪 while 循环中哪个整数输入最小和最大？

Question

我是 C++ 编程的新手，只是一般编程，当我卡在第 4 章练习 6 时，我正在学习 Stroustrup 的编程原则和使用 C++ 第 2 版的实践。

问题是:编写一个包含 while 循环的程序，该循环读取两个 int，然后打印它们。改变程序写出较小的值，和较大的值。等等等等现在更改循环体，使其每次只读取一个 double。定义两个变量以跟踪您目前看到的最小值和最大值。每次循环都写出输入的 vlue 如果它是迄今为止最小的，则在数字后面写下迄今为止最小的值。如果是迄今为止最大的，就在数字后面写上迄今为止最大的。

基本上，我很难让最小值和最大值在所有循环中运行。因为，目前，所有发生的事情是，每次我输入两个数字时，它只会显示哪个是我之前在程序中已经达到的最大/最小。它不会维护最大/最小值，直到在其中一个循环中有一个更小/更大的值。

我希望我能够清楚地解释情况。我确定这只是一个非常简单的修复，我是编程新手。到目前为止，这是我的代码:

#include "../../../std_lib_facilities.h";

int main()
{
    double val1;
    double val2;
    double largest =0  ;
    double smallest= 0 ;
    double input = 0;

    char exit = ' ';

    while (exit != 'x') {
        cout << "Please enter two numbers.\n";
        cin >> val1 >> val2;
        cout << "The two values you have entered are: " << val1 << " and " << val2 << "\n";

        if (val1 < val2) {
            cout << "The smaller value is: " << val1 << ". The larger value is: " << val2 << ".\n";
            if (val2 - val1 <= .5)
                cout << "The numbers are almost equal.\n";
        }
        else if (val2 < val1) {
            cout << "The smaller value is: " << val2 << ". The larger value is: " << val1 << ".\n";
            if (val1 - val2 <= .5)
                cout << " The numbers are almost equal.\n";
        }
        else
            cout << "The two numbers " << val1 << " are equal!\n"; \

            if (val1 < smallest && val2>val1) {
                cout << val1 << " is the smallest so far.\n";
                smallest = val1;
            }
            else if (val2<smallest && val1>val2) {
                cout << val2 << " is the smallest so far.n";
                smallest = val2;
            }
            else {}


            if (val1 > largest && val2 < val1) {
                cout << val1 << " is the largest so far.\n";
                val1 = largest;
            }
            else if (val2 > largest && val1 < val2) {
                cout << val2 << " is the largest so far.\n";
                val2 = largest;
            }
            else {

            }

            cout << "If you would like to exit this program, please enter x. Otherwise, enter any other key to continue. \n";
            cin >> exit;
    }
}

Answer 1

您没有正确跟踪最大值。

            cout << val1 << " is the largest so far.\n";
            val1 = largest;  // Wrong

需要

            cout << val1 << " is the largest so far.\n";
            largest = val1;

和

            cout << val2 << " is the largest so far.\n";
            val2 = largest;  // Wrong

需要

            cout << val2 << " is the largest so far.\n";
            largest = val2;