提高:: ptr_vector和find_if [英] boost::ptr_vector and find_if

问题描述

我有一个类：

//header file
class CMDatabase
{
    class Try;
    typedef boost::shared_ptr<Try> TryPtr;
    typedef boost::ptr_vector<Try> TryVector;
    typedef TryVector::iterator TryVectorIterator;

    class Try
    {
        public:
            virtual ~Try();
            virtual bool equal(CMDatabase::TryPtr mySd) = 0;
    };
};

//.cpp file

class TryImpl : public CMDatabase::Try
{
    bool equal(CMDatabase::TryPtr mySd)
    {
        //boost::shared_ptr<ServiceDataImpl> ServiceDataImplPtr;
        //const ServiceDataImplPtr pOtherData = dynamic_cast<const ServiceDataImplPtr>(mySd);

        //ServiceDataImpl *pOtherData = dynamic_cast<ServiceDataImpl *>(mySd.get());
        return true;
    }
};

//Another .cpp file

void UpdateClass::TryFind()
{
    CMDatabase::TryVector defaultTry;
    CMDatabase::TryVector updateTry;

//Code for filling two vectors here....

    for(CMDatabase::TryVectorIterator i = defaultTry.begin(); i != defaultTry.end(); ++i)
    {
       CMDatabase::TryVectorIterator it = find_if(updateTry.begin(), updateTry.end(),bind1st(mem_fun(&CMDatabase::Try::equal), *i));

    }
}

当我编译，我得到错误：

When I compile this, I get error:

错误1错误C2440：初始化'：结果
  不能转换从'常量CMDatabase ::尝试'到'CMDatabase ::尝试结果
  *C：\\ Program Files文件\\微软的Visual Studio 9.0 \\ VC \\包括\\功能296

Error 1 error C2440: 'initializing' :
cannot convert from 'const CMDatabase::Try' to 'CMDatabase::Try
*' c:\program files\microsoft visual studio 9.0\vc\include\functional 296

谁能pelase告诉我它是什么，我做错了，以及如何纠正它。

Can anyone pelase tell me what is it that I am doing wrong and how to correct it.

推荐答案

只是为了完整起见，下面的语句是错误的！感谢马修M.指出我的错误！

在提领升压指针容器的迭代器，你会得到纯净的指针元素。所以，你可以尝试取消引用您通过迭代得到纯净的指针：

On dereferencing an iterator of the boost pointer container you will get the pure pointer to the element. So you can try to dereference the pure pointer you get through the iterator:

CMDatabase::TryVectorIterator it =
  find_if(updateTry.begin(), updateTry.end(), bind1st(mem_fun(&CMDatabase::Try::equal), **i));

---

当以下仍然是正确的;）

或者你可以使用的运算符[] 实施的boost :: ptr_vector 将返回一个参考到元素

Or you can use the the operator[] implementation of the boost::ptr_vector which will return a reference to the element:

for (std::size_t i = 0, l = ; defaultTry.size(); ++i) {
  CMDatabase::TryVectorIterator it = std::find_if(
    updateTry.begin(),
    updateTry.end(),
    std::bind1st(std::mem_fun(&CMDatabase::Try::equal), defaultTry[i])
  );
}

希望这有助于。

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