错误C2011：'XX'：'类'类型重新定义 [英] Error C2011: 'XX' : 'class' type redefinition

问题描述

我有这个编译器错误（C2011）与这段代码。

I have this compiler error (C2011) with this piece of code. I don't know what is wrong with it.

命名空间（Ogre）没有 PlaneMovement 。我也尝试了不同的名称，但仍然有相同的错误。

The namespace (Ogre) doesn't have a definition for PlaneMovement. I also tried a different name and still the same errors.

#include <Ogre.h>

using namespace Ogre;

class PlaneMovement
{
public:
    PlaneMovement(Degree startingAngle, Real velocity = 2, Real gravity = 2);
    Vector2 updateMovement(const FrameEvent& evt);
private:
    Degree currentAngle;
    Real currentVelocityX;
    Real currentVelocityY;
    Real gravity;
    bool top;
};

推荐答案

包含警卫：

#ifndef FILE_H
#define FILE_H

//file contents here

#endif

头文件应该包含警告，因为这个确切的原因 - 多个包含在同一个翻译单元可以导致多个定义。

Header files should have include guards for this exact reason - multiple inclusion in the same translation unit can lead to a multiple definition.

替代方法是使用

#pragma once

，但并非所有编译器都支持。

but this isn't supported by all compilers.

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