c++ - vector 无法初始化

Question

我正在尝试初始化自定义类型的 vector dataCard:

vector<dataCard> dataSet;
dataSet.reserve(200);

但是编译器不允许我这样做，指示第二行出现错误(我尝试为容器保留空间):

required from here

但是当我将声明更改为以下内容时

vector<dataCard*> dataSet;

它开始工作。

编译器不允许我按原样使用我的类型，但允许我使用指向该类型的指针，这可能是什么原因？我实际上需要一个对象 vector ，而不是指向它们的指针。

编辑

dataCard的头文件

#include <card.h>


class dataCard {
    char* name; // name according to the filename
    char Class; // Classes: 2, 3, 4, 5, 6, 7, 8, 9, T, J, Q, K, A
    double distanceToQuery;
public:
    void resetDistance();
    int numBlackTotal (bitmap* bmp);
    bitmap image;
    int numOfBlackPixels;
    char* getName();
    void setName(char* n);
    void setClass (char* c);
    char* getClass();
    void setDistance(double distance);
    double getDistance ();
    dataCard(const char* fname);
    dataCard();
    virtual ~dataCard();
};

这是来自编译器的错误消息

/usr/include/c++/4.7/bits/stl_uninitialized.h:77:3:   required from ‘static _ForwardIterator std::__uninitialized_copy<_TrivialValueTypes>::__uninit_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = dataCard*; _ForwardIterator = dataCard*; bool _TrivialValueTypes = false]’
/usr/include/c++/4.7/bits/stl_uninitialized.h:119:41:   required from ‘_ForwardIterator std::uninitialized_copy(_InputIterator, _InputIterator, _ForwardIterator) [with _InputIterator = dataCard*; _ForwardIterator = dataCard*]’
/usr/include/c++/4.7/bits/stl_uninitialized.h:260:63:   required from ‘_ForwardIterator std::__uninitialized_copy_a(_InputIterator, _InputIterator, _ForwardIterator, std::allocator<_Tp>&) [with _InputIterator = dataCard*; _ForwardIterator = dataCard*; _Tp = dataCard]’
/usr/include/c++/4.7/bits/stl_vector.h:1112:8:   required from ‘std::vector<_Tp, _Alloc>::pointer std::vector<_Tp, _Alloc>::_M_allocate_and_copy(std::vector<_Tp, _Alloc>::size_type, _ForwardIterator, _ForwardIterator) [with _ForwardIterator = dataCard*; _Tp = dataCard; _Alloc = std::allocator<dataCard>; std::vector<_Tp, _Alloc>::pointer = dataCard*; std::vector<_Tp, _Alloc>::size_type = long unsigned int]’
/usr/include/c++/4.7/bits/vector.tcc:76:70:   required from ‘void std::vector<_Tp, _Alloc>::reserve(std::vector<_Tp, _Alloc>::size_type) [with _Tp = dataCard; _Alloc = std::allocator<dataCard>; std::vector<_Tp, _Alloc>::size_type = long unsigned int]’
/home/ppsadm01/Documents/vgv/src/main.cc:145:22:   required from here
/usr/include/c++/4.7/bits/stl_construct.h:85:7: error: no matching function for call to ‘dataCard::dataCard(const dataCard&)’

Answer 1

正如错误消息所示，您需要实现复制构造函数 dataCard::dataCard(const dataCard&) 。您需要它，因为例如 vector<dataCard>::push_back()将复制dataCard实例。

当您编写复制构造函数时，请注意以正确的方式复制所有成员变量。因此，一个示例实现可能是

dataCard::dataCard(const dataCard &rhs)
{
    strcpy(name, rhs.name);
    Class = rhs.Class;
    distanceToQuery = rhs.distanceToQuery;
    image = rhs.image; // make sure that this is OK!
}