没有为类x（继承）C ++存在默认构造函数 [英] no default constructor exists for class x (inheritance) C++

问题描述

我有以下三个标题：

IBaseStates.h

class IBaseStates
{
public:
    enum STATE;

    virtual void Update( STATE state ) = 0;
};

PlayerStates.h

#pragma once

#include "IBaseStates.h"
#include "Player.h"

class PlayerStates : public IBaseStates, public Player
{
public:
    enum STATE {
        FLYING,
        FALLING
    };

    int textureAmount;

    PlayerStates();
    ~PlayerStates( );

    void Update( STATE state );
};

Player.h

#pragma once

#include "StructVertex.h"
#include "SquareVertices.h"
#include "WICTextureLoader.h"

using namespace Microsoft::WRL;
using namespace DirectX;
//using namespace DirectX;

class Player : public SquareVertices
{
public:
    Player( ComPtr<ID3D11Device1> d3dDevice );
    ~Player();

    void Initialize();
    void Update();

    float x;
    float y;
    float z;
    float rotation;
    float velocity;

    ComPtr<ID3D11Buffer> vertexbuffer;
    ComPtr<ID3D11Buffer> indexbuffer;
    ComPtr<ID3D11ShaderResourceView> texture[3];
protected:
    const ComPtr<ID3D11Device1> d3dDevice;
};

为什么当我为PlayerStates.cpp文件中的PlayerStates类定义一个构造函数时， p>

Why when I define a constructor for my PlayerStates class in my PlayerStates.cpp file do I get

no default constructor exists for class Player

PlayerStates.cpp

#include "pch.h"
#include "PlayerStates.h"

PlayerStates::PlayerStates()
: 
    textureAmount( 3 )
{
}

推荐答案

当你声明一个类的非默认构造函数时，不再生成默认的。所以你必须提供自己的。

When you declare a non-default constructor for a class, the compiler does not generate a default one anymore. So you have to provide your own.

PlayerStates 需要调用其基类的默认构造函数 Player 在其自己的默认构造函数。所以你需要用默认构造函数提供 Player ，或者从 PlayerStates '默认构造函数中调用非默认构造函数初始化列表。

PlayerStates needs to call a default constructor of its base class Player in its own default constructor. So you either need to provide Player with a default constructor, or call it's non-default constructor from PlayerStates' default constructor initialization list.

这隐含地调用 Player :: Player（）。

PlayerStates::PlayerStates() : textureAmount( 3 ) {}

这将调用单个参数构造函数：

This calls the single argument constructor:

PlayerStates::PlayerStates() : Player(someComPtr), textureAmount( 3 ) {}

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