C++ 错误：重新定义类
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/26179408/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
error: redefinition of class
提问by Aviv Cohn
Here's my code:
这是我的代码：
// in main.cpp
#include "iostream"
#include "circle.cpp"
#include "rectangle.cpp"
#include "shape.cpp"
using namespace std;
int main() {
Shape shapes[10];
for (int i = 0; i < 10; i++){
if (i % 2)
shapes[i] = Circle(5);
else
shapes[i] = Rectangle(10, 10);
cout << shapes[i].getArea();
}
return 0;
}
// in circle.cpp
#include "shape.cpp"
class Circle : public Shape {
private:
int radius;
static const double PI = 3.14159265358979323846;
public:
Circle (int radius) : radius(radius) {}
virtual int getArea() const {
return PI * radius*radius;
};
virtual int setRadius(int radius){
radius = radius;
}
};
// in rectangle.cpp
#include "shape.cpp"
class Rectangle : public Shape {
private:
int width;
int height;
public:
Rectangle(int width, int height) : width(width), height(height){}
virtual int getArea() const {
return width * height;
}
virtual void setWidth(int width){
this->width = width;
}
virtual void setHeigth(int height){
this->height = height;
}
};
// in shape.cpp
class Shape {
public:
virtual int getArea() const = 0;
};
When compiling, I get this error:
编译时，我收到此错误：
error: redefinition of 'class Shape'
How can I fix this?
我怎样才能解决这个问题？
回答by James Thorpe
Your main.cpp includes files which include shape.cpp, which ends up being included multiple times. You can avoid this by wrapping your included files with a check for a definition:
您的 main.cpp 包含包含 shape.cpp 的文件，最终会被多次包含。您可以通过检查定义来包装包含的文件来避免这种情况：
#ifndef SHAPE_CPP
#define SHAPE_CPP
//file contents
#endif
回答by Stephane Rolland
You should structure your code between .h (headers) and .cpp files (implementation).
您应该在 .h（头文件）和 .cpp 文件（实现）之间构建您的代码。
You should include header files: .hNever include .cppfiles. (Unless you know what you do, and that would be in really rare cases).
您应该包含头文件：.h永远不要包含.cpp文件。（除非您知道自己在做什么，而且这种情况在非常罕见的情况下）。
Otherwise you're ending compiling several times your class, and you get the error your compiler is telling you: 'redefinition of class...'
否则，您将多次结束类的编译，并且您会收到编译器告诉您的错误：“重新定义类...”
