如何在 class 名称中创建一个带有变量名称的 class？

Question

所以，这是我的代码：

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

using namespace std;

class rectangle {
public:
    double width;
    double height;
    rectangle(double, double);
    double area() { return (width*height);}
};

rectangle::rectangle(double a, double b) {
    width = a;
    height = b;
}

int main() {
    cout << "How many rectangles would you like to create? ";
    int rectNum;
    cin >> rectNum;

    for (int counter = 0; counter < rectNum; counter++) {
        int rectCount = 1;
        rectCount = counter + 1;
        double rectWidth, rectHeight;
        cout << "\nEnter width of rectangle " << rectCount << ": ";
        cin >> rectWidth;
        cout << "\nEnter height of rectangle " << rectCount << ": ";
        cin >> rectHeight;
        rectangle rect/*integer value of rectCount at current time*/(rectWidth, rectHeight);
    }

    return 0;
}

正如评论区所说，我想创建一个名为rect的矩形，其后缀是整数rectCount的当前值。我该怎么做？提前致谢！

Answer 1

变量名必须在编译时定义，这样你试图做的就不会起作用。

Answer 2

这个习语在 C++ 中从来没有用过。正确的方法是将矩形存储在像 std::vector 这样的容器中，它会自动增长和收缩以满足您的需要。然后，您可以循环遍历向量，而不必担心其中实际有多少元素。

std::vector<rectangle> rects(rectNum);

for (int counter = 0; counter < rectNum; counter++) {
    /* .. */
    rects.emplace_back(rectWidth, rectHeight);
}

实际上不需要循环。 std::vector 的构造函数会为您处理。

std::vector<rectangle> rects(rectNum, {rectWidth, rectHeight});

您需要包含 <vector> 才能使用 std::vector。

Answer 3

动态设置 class 名称在 C++ 中是不可能的。但是，静态变量可用于存储运行个矩形：

#include <iostream>
#include <conio.h>
using namespace std;

class rectangle 
{
    public:
        double width;
        double height;
        static int rectCount; //declare static variable
        rectangle(double, double);
        double area() { return (width*height);}
};

int rectangle::rectCount=0; //initialize static variable

rectangle::rectangle(double a, double b) 
{
    width = a;
    height = b;
    rectCount++;
}

int main() 
{
    cout << "How many rectangles would you like to create? ";
    int rectNum;
    cin >> rectNum;

    for (int counter = 0; counter < rectNum; counter++) 
    {
        int rectCount = 1;
        rectCount = counter + 1;
        double rectWidth, rectHeight;
        cout << "\nEnter width of rectangle " << rectCount << ": ";
        cin >> rectWidth;
        cout << "\nEnter height of rectangle " << rectCount << ": ";
        cin >> rectHeight;
        rectangle rect=rectangle(rectWidth, rectHeight);
        cout<<"rectCount value: "<<rectCount;
      }

return 0;
}

如何在 class 名称中创建一个带有变量名称的 class？

How would I create a class with a variable name in the class name?

c++

class

variables

int