使用std :: vector不匹配operator = [英] no match for operator= using a std::vector

问题描述

我有一个这样宣布的课程：

I've got a class declared like this:

class Level
{
    private:
        std::vector<mapObject::MapObject> features;
    (...)
};

，在其成员函数之一中，我尝试遍历该向量，如下所示：

and in one of its member functions I try to iterate through that vector like this:

vector<mapObject::MapObject::iterator it;
for(it=features.begin(); it<features.end(); it++)
{
    /* loop code */
}

这对我来说似乎很简单，但是g ++给了我这个错误：

This seems straightforward to me, but g++ gives me this error:


src / Level.cpp：402：错误：'it =（（const yarl :: level :: Level *）this）-> yarl中'operator ='不匹配：level :: Level :: features.std :: vector< _Tp，_Alloc> :: begin [with _Tp = yarl :: mapObject :: MapObject，_Alloc = std :: allocator< yarl :: mapObject ::: MapObject>]（）'

/usr/include/c++/4.4/bits/stl_iterator.h:669：注意：候选人为： __gnu_cxx :: __ normal_iterator< yarl :: mapObject :: MapObject *， std :: vector>>& __ gnu_cxx :: __ normal_iterator< yarl :: mapObject :: MapObject *， std :: vector> > :: operator =（const __gnu_cxx :: __ normal_iterator< ; yarl :: mapObject :: MapObject *，``std :: vector< yarl :: mapObject :: MapObject，std :: allocator< yarl :: mapObject :: MapObject>>&&）


src/Level.cpp:402: error: no match for ‘operator=’ in ‘it = ((const yarl::level::Level*)this)->yarl::level::Level::features.std::vector<_Tp, _Alloc>::begin [with _Tp = yarl::mapObject::MapObject, _Alloc = std::allocator<yarl::mapObject::MapObject>]()’
/usr/include/c++/4.4/bits/stl_iterator.h:669: note: candidates are: __gnu_cxx::__normal_iterator<yarl::mapObject::MapObject*,std::vector > >& __gnu_cxx::__normal_iterator<yarl::mapObject::MapObject*,std::vector > >::operator=(const __gnu_cxx::__normal_iterator<yarl::mapObject::MapObject*, ``std::vector<yarl::mapObject::MapObject, std::allocator<yarl::mapObject::MapObject> > >&)

有人知道为什么会这样吗？

Anyone know why this is happening?

推荐答案

我猜这部分错误描述了您的问题：

I'd guess that this part of the error describes your problem:

(const yarl::level::Level*)this

是在其中找到此代码的成员函数a const限定的成员函数？如果是这样，则需要使用 const_iterator ：

Is the member function in which this code is found a const-qualified member function? If so, you'll need to use a const_iterator:

vector<mapObject::MapObject>::const_iterator it;

如果成员函数是const限定的，则只有const限定的<$ c $重载成员向量上的c> begin（）和 end（）将可用，并且两者都返回 const_iterator s。

If the member function is const-qualified, then only the const-qualified overloads of begin() and end() on the member vector will be available, and both of those return const_iterators.

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