C++ 成员函数多态性问题

Question

我遇到了 C++ 继承成员函数的问题，请看下面的代码：

binIO_t wtest(path, mode);
const void* Buff = "abcd";
wtest << Buff, 1; //no operator found
wtest.virtIO_t::operator<<(Buff), 1; //works fine

确切的编译器错误是：

Error 1 error C2679: binary '<<' : no operator found which takes a right-hand operand of type 'void *' (or there is no acceptable conversion) ...

我确实遗漏了一些微妙的减法，但我没能找到它。

我的 superclass.h 是：

#pragma once
#include <string>
#include <iostream>
#include <fstream>
#include <stdio.h>

using namespace std;

class virtIO_t{
private:
    virtIO_t();

public:
    virtIO_t(string filePath, string fileMode);
    ~virtIO_t();

    virtual virtIO_t& operator >> (void* Buf);
    virtual virtIO_t& operator << (const void* Buf);

    virtual virtIO_t& operator << (const char val) = 0;
    virtual virtIO_t& operator >> (char &val) = 0;
};

而 superclass.cpp 是：

#include "stdafx.h"
#include "virtIO_t.h"

virtIO_t::virtIO_t()
{
}

virtIO_t::~virtIO_t()
{
    ...
}

virtIO_t::virtIO_t(string filePath, string fileMode){
...
}


virtIO_t& virtIO_t::operator << (const void* Buff){
    ...
}
virtIO_t& virtIO_t::operator >> (void* Buff){
    ...
}

而 sub.h 是：

#pragma once
#include "virtIO_t.h"

class binIO_t : public virtIO_t{

public:
    binIO_t(string filePath, string mode);

    virtIO_t& operator << (const char val);
    virtIO_t& operator >> (char &val);

而 sub.cpp 是：

#include "stdafx.h"
#include "binIO_t.h"

binIO_t::binIO_t(string filePath, string mode) : virtIO_t(filePath, (string(mode) + "b").c_str()){}

    virtIO_t& binIO_t::operator << (const char val){
    ...
    }

    virtIO_t& binIO_t::operator >> (char &val){
    ...
    }

Answer 1

binIO_t 声明它自己的 operator<<，它从基础 class 中隐藏了 operator<<(void*)。尝试 using virtIO_t::operator<< 指令或在 biunIO_t.

中明确定义 operator<<(void*)

另外：, 1什么都不做。

C++ 成员函数多态性问题

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