无法将对象push_back到矢量

Question

错误:我们在调用抛出的代码片段异常时出现以下错误:读取访问冲突。std::_Vector_alloc > >::_Myend(...)返回0xC。

bool _Has_unused_capacity() const _NOEXCEPT
{   // micro-optimization for capacity() != size()
return (this->_Myend() != this->_Mylast());
}

代码片段:错误:我们在调用代码片段异常抛出:读取访问冲突时出现以下错误。std::_Vector_alloc > >::_Myend(...)返回0xC。

bool _Has_unused_capacity() const _NOEXCEPT
{   // micro-optimization for capacity() != size()
return (this->_Myend() != this->_Mylast());
}


class  A 
{
public:
    class B *objTRANSACTIONID;
};
// second class
class  B {
public:
    std::vector<class C * >TRANSACTIONID;
};
// Third class
class C {
public:
    std::string *APPLICATIONID;
    std::string *CREATEDBY;
};
//  C++ Code
int main()
{
    A *aObject =new A();
    C *DNINFO = new C();
    std::string FieldName = "UserType";
    DNINFO->APPLICATIONID = &FieldName;
    DNINFO->CREATEDBY = &FieldName;
    // Throws error as “unused capacity” for vector.
    aObject->objTRANSACTIONID->TRANSACTIONID.push_back(DNINFO);
}

Answer 1

您的A对象具有未初始化的objTRANSACTIONID，没有B对象可将DNINFO推送到其TRANSACTIONID中。

如果可以，请不要在这里使用指针和new

// Third class
class C {
public:
    std::string APPLICATIONID;
    std::string CREATEDBY;
};

// second class
class  B {
public:
    std::vector<C>TRANSACTIONID;
};

class  A 
{
public:
    B objTRANSACTIONID;
};


//  C++ Code
int main()
{
    A aObject;
    C DNINFO;
    std::string FieldName = "UserType";
    DNINFO->APPLICATIONID = FieldName;
    DNINFO->CREATEDBY = FieldName;
    aObject.objTRANSACTIONID.TRANSACTIONID.push_back(DNINFO);
}

显然，您的类是由工具生成的，因此在这种情况下，您必须分配一个B。注意，这个工具应该告诉你什么时候(或者是否) deletes的东西。如果不是这样，那就丢掉这个工具，自己编写合理的类。

//  C++ Code
int main()
{
    A  aObject;
    aObject.objTRANSACTIONID = new B;
    C * DNINFO = new C;
    DNINFO->APPLICATIONID = new std::string("UserType"); // have to assume owning raw pointer
    DNINFO->CREATEDBY = new std::string("UserType"); // have to assume owning raw pointer
    aObject.objTRANSACTIONID->TRANSACTIONID.push_back(DNINFO);
}