c++ - 程序失败。 sharedPtr vector C++

Question

拜托，我真的需要帮助..不要因为 sharedPtr 的实现而 panic
我的 C++ 项目有问题。在我的项目中，我正在创建一家公司，该公司拥有有关其员工(艺术家、程序员、经理)、项目、……的所有信息。为了容纳所有员工，我使用了一个 SharedPtr vector (使用自己的实现)

而且看起来 vector 出现了一些问题:

Unhandled exception at 0x00CC8CA9 in projComp.exe: 0xC0000005: Access violation reading location 0x00000044.

并指出 vector 中的这个断点-

bool _Inside(const value_type *_Ptr) const
    {   // test if _Ptr points inside vector
    return (_Ptr < this->_Mylast && this->_Myfirst <= _Ptr);
    }

这是我的 SharedPtr 实现:

#ifndef _SHARED_PTR_H_
#define _SHARED_PTR_H_

#include "RCObject.h"

template<class T>
class SharedPtr {

public:
    SharedPtr(T* realPtr = 0);
    SharedPtr(const SharedPtr& rhs);
    ~SharedPtr();

    SharedPtr& operator=(const SharedPtr& rhs);
    const T* operator->() const;
    T* operator->();
    const T& operator*() const;
    T& operator*();

    template<class newType>           // template function for   
    operator SharedPtr<newType>()      // implicit conversion ops.   
    {     
        return SharedPtr<newType>(counter->pointee);
    }

private:
    struct CountHolder : public RCObject {
        ~CountHolder() { delete pointee; }
        void addReference() {
            ++refCount;
        }
        void removeReference() {
            if (--refCount == 0)delete this;
        }
        T *pointee;
    };

    CountHolder *counter;
    void init();
    void makeCopy();
};


template <class T>
void SharedPtr<T>::init() {
    if (counter->isShareable() == false) {
        T *oldValue = counter->pointee;
        counter = new CountHolder;
        counter->pointee = new T(*oldValue);
    }
    counter->addReference();
}

template <class T>
SharedPtr<T>::SharedPtr(T* realPtr) : counter(new CountHolder) {
    counter->pointee = realPtr;
    init();
}

template <class T>
SharedPtr<T>::SharedPtr(const SharedPtr& rhs) : counter(rhs.counter) {
    init();
}

template <class T>
SharedPtr<T>::~SharedPtr() {
    counter->removeReference();
}

template <class T>
SharedPtr<T>& SharedPtr<T>::operator=(const SharedPtr& rhs) {
    if (counter != rhs.counter)    {
        counter->removeReference();
        counter = rhs.counter; 
        init();
    }
    return *this;
}

template <class T>
void SharedPtr<T>::makeCopy() {
    if (counter->isShared()) {
        T *oldValue = counter->pointee;
        counter->removeReference();
        counter = new CountHolder;
        counter->pointee = new T(*oldValue);
        counter->addReference();
    }
}

template <class T>
const T* SharedPtr<T>::operator->() const {
    return counter->pointee;
}

template <class T>
T* SharedPtr<T>::operator->() {
    makeCopy();
    return counter->pointee;
}

template <class T>
const T& SharedPtr<T>::operator*() const {
    return *(counter->pointee);
}

template <class T>
T& SharedPtr<T>::operator*() {
    makeCopy();
    return *(counter->pointee);
}

#endif

这是 RCObject:

#ifndef _RCOBJ_H_
#define _RCOBJ_H_

#include <iostream>
using namespace std;

class RCObject {
//private:
protected:
    int refCount;
    bool shareable;

protected:
    RCObject();
    RCObject(const RCObject&);
    virtual ~RCObject() = 0;

    RCObject& operator=(const RCObject&);

public:
    virtual void addReference() = 0;
    virtual void removeReference() = 0;
    void markUnshareable();
    bool isShareable() const;
    bool isShared() const;

};

#endif

及其实现:

#include <iostream>
#include "RCObject.h"
using namespace std;


RCObject::RCObject() : refCount(0), shareable(true) {
}

RCObject::RCObject(const RCObject&) : refCount(0), shareable(true) {
}

RCObject& RCObject::operator=(const RCObject&) {
    return *this;
}

RCObject::~RCObject() {
}

void RCObject::addReference() {
    ++refCount;
}

void RCObject::removeReference() {
    if (--refCount == 0) delete this;
}

void RCObject::markUnshareable() {
    shareable = false;
}

bool RCObject::isShareable() const {
    return shareable;
}

bool RCObject::isShared() const {
    return refCount > 1;
}

问题在于此代码行:

void Company::addArtist(vector<string> empAfield, string idCmp, string currPrj, double currPrjHrs, double ttlHrs, double exp, bool isEmp, double hrsDay, string name, string lastName, string idPrsn, long phoneNum) {
    _employeeList.push_back(SharedPtr<Artist>(new Artist(empAfield, idCmp, currPrj, currPrjHrs, ttlHrs, exp, isEmp, hrsDay, name, lastName, idPrsn, phoneNum)));
}

抱歉，代码太长了，我一直在思考是什么导致了这个问题。也许 vector 在它已经被释放后删除了 SharedPtr？这不应该是，但我想不通了。

感谢所有试图挽救我痛苦的人；)

Answer 1

错误位置是 0x00000044，这通常意味着 this 在方法调用中为 NULL，而它正在尝试访问成员变量(在位置 this+0x44在这种情况下)。

检查您是否在 NULL Company* 指针上调用 addArtist()。