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Why can't variables be declared in a switch statement?（23个答案）
3天前关闭。
我有两个文件。一个是名为shape.h的头文件。我想通过头文件从类中调用形状。但是文件没有编译。

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

class Shape{
    protected:
        int x;
        int y;
    public:
        Shape(){
            x =0;
            y = 0;
            int gd = DETECT, gm;
            char pathtodriver[] = "";
            initgraph(&gd, &gm, pathtodriver);
        }
        virtual void draw();
};

class Rectangle : public Shape{
    protected:
        int x1;
        int y1;

    public:

        Rectangle(int x, int y,int x1,int y1){
            this->x = x;
            this->y = y;
            this->x1 = x1;
            this->y1 = y1;
        };

        void draw(){
            rectangle(200,200,100,250);
            closegraph();
        };
};

class Circle : public Shape{
    protected:
        int x1;

    public:

        Circle(int x,int y,int x1){
            this->x = x;
            this->y = y;
            this->x1 = x1;
        };
        void draw(){
            circle(x,y,x1);
            closegraph();
        };
};

class Ellipse : public Shape{
    protected:
        int a;
        int b;
        int x1;
        int y1;

    public:

        Ellipse(int x,int y,int a, int b,int x1,int y1){
            this->x = x;
            this->y = y;
            this->a = a;
            this->b = b;
            this->x1 = x1;
            this->y1 = y1;
        };
        void draw(){
            ellipse(x,y,a,b,x1,y1);
            closegraph();
        };
};

和另一个要在形状中调用的文件。

#include "shape.h"
using namespace std;

int main(){
    Shape *s1;
    cout<<"1.Rectangle"<<
    "2.Circle"<<
    "3.Ellipse"<<
    "4.Exit"<<endl;
    int choice;
    cout<<"Enter your choice :"<<endl;
    cin >> choice;
    switch(choice){
    case 1:
        Rectangle R1(100,100,50,60);
        s1 = &R1;
        s1->draw();
        break;

    case 2:
        Circle c1(100,100,20);
        s1 = &c1;
        s1 ->draw();
        break;

    case 3:
        Ellipse e1(100,100,0,360,30,40);
        s1 = &e1;
        s1->draw();
        break;

    case 4:
        exit(0);

    default:
        cout<<"Error choice";
    }

}

但它给出了以下错误：

||=== Build file: "no target" in "no project" (compiler: unknown) ===|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\shape.h||In constructor 'Shape::Shape()':|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\shape.h|14|warning: ISO C++ forbids converting a string constant to 'char*' [-Wwrite-strings]|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp||In function 'int main()':|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|13|error: expected ';' before 'R1'|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|14|error: 'R1' was not declared in this scope|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|20|error: jump to case label [-fpermissive]|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|17|note:   crosses initialization of 'Circle c1'|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|21|error: expected ';' before 'e1'|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|22|error: 'e1' was not declared in this scope|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|24|error: jump to case label [-fpermissive]|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|17|note:   crosses initialization of 'Circle c1'|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|27|error: jump to case label [-fpermissive]|
C:\Users\rbmoh\OneDrive\Desktop\Docs\C++\labb7.cpp|17|note:   crosses initialization of 'Circle c1'|
||=== Build failed: 7 error(s), 1 warning(s) (0 minute(s), 0 second(s)) ===|

请帮帮忙
我试着改变类名，但是效果不好。代码没有编译。