c++ - 已编译的 C++ 应用程序提供随机浮点值

Question

在编译控制台应用程序并输入错误数据后，它在请求数字时给出奇怪的输出值，如 2.0434e-006。这是代码:

#include <iostream>
#include <conio.h>

int main() {
    using namespace std;
    float l,w,h;
    float s;
    cout << "\nCalculating surface area of the parallelepiped\n";
    cout << "Enter the raw data:\n";
    cout << "Length (cm)  -> ";
    cin >> l;
    cout << "Width (cm) -> ";
    cin >> w;
    cout << "Height (cm) -> ";
    cin >> h;
    s = (l*w + l*h + w*h)*2;
    cout << "Surface area: " << s << " sq. cm\n";
    cout << "\n\nPress any key...";
    getch();
    }

我听说过一些关于 IEEE 754 浮点错误的消息，但即使是这些信息也不能确定我的知识。

Answer 1

未初始化的非静态局部变量的值是不确定的。

检查输入是否成功并处理错误。

#include <iostream>

int main() {
    using namespace std;
    float l,w,h;
    float s;
    cout << "\nCalculating surface area of the parallelepiped\n";
    cout << "Enter the raw data:\n";
    cout << "Length (cm)  -> ";
    if (!(cin >> l)) {
        cout << "input error\n";
        return 1;
    }
    cout << "Width (cm) -> ";
    if (!(cin >> w)) {
        cout << "input error\n";
        return 1;
    }
    cout << "Height (cm) -> ";
    if (!(cin >> h)) {
        cout << "input error\n";
        return 1;
    }
    s = (l*w + l*h + w*h)*2;
    cout << "Surface area: " << s << " sq. cm\n";
    cout << "\n\nPress any key...";
}