std ::查找一组shared_ptr

Question

我敢肯定我在这里做了些蠢事,但我看不到它.以下为什么不编译？

#include <algorithm>
#include <memory>
#include <vector>
#include <string>

// A class to play with.  Encapsulates a name.
class StringClass
{
public:
    StringClass(std::string const & name) : MyName(name) 
    {
    }

    std::string const & Name() const
    {
        return MyName;
    }

private:
    std::string MyName;
};

// The set of instances of "StringClass".

std::vector<std::shared_ptr<StringClass>> MyInstances;

// Function returns "true" if a class with the given name exists in the collection.
bool Exists(std::string const & name)
{
    auto i = std::find(MyInstances.begin(), MyInstances.end(), [&](std::shared_ptr<StringClass> const & instance) {
        return instance->Name() == name;
    });

    return i != MyInstances.end();
}

我已经为一个类创建了一个shared_ptr的向量.该类具有Name()属性.我想要做的就是迭代向量,寻找具有给定名称的类的实例.但是,它没有编译:(.

错误是:

1> ClCompile:1> test.cpp 1> c:\ program files(x86)\ microsoft visual studio 10.0\vc\include\algorithm(41):错误C2679:二进制'==':找不到哪个操作符右转'const anonymous-namespace' 类型的手操作数 ::)'1> with 1> [1> _Ty = StringClass 1> ] 1> c:\ program files(x86)\ microsoft visual studio 10.0\vc\include\algorithm (74):参见函数模板实例化'_InIt std :: _ Find*,anonymous-namespace'::&)'正在编译1> 1> [1> _InIt = std :: tr1 :: shared_ptr*,1> _Ty = StringClass 1>] 1> c:\ svn\trunk\test\test\test.cpp(55):参见函数模板实例化'_InIt std :: find,anonymous-namespace':: 1>] 1> stdafx.cpp 1>生成代码... 1> 1>构建失败.1> 1>经过时间00:00:00.87 ==========构建:0成功,1失败,0最新,0跳过==========anonymous-namespace'::<lambda0>' (or there is no acceptable conversion) 1> could be 'built-in C++ operator==(std::_Bool_type, std::_Bool_type)' 1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\exception(470): or 'bool std::operator ==(const std::_Exception_ptr &,const std::_Exception_ptr &)' 1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\exception(475): or 'bool std::operator ==(std::_Null_type,const std::_Exception_ptr &)' 1>
c:\program files (x86)\microsoft visual studio 10.0\vc\include\exception(481): or 'bool std::operator ==(const std::_Exception_ptr &,std::_Null_type)' 1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\system_error(408): or
'bool std::operator ==(const std::error_code &,const std::error_condition &)' 1> c:\program files (x86)\microsoft visual studio 10.0\vc\include\system_error(416): or 'bool std::operator ==(const std::error_condition &,const std::error_code &)' 1> while trying to match the argument list '(std::tr1::shared_ptr<_Ty>, const
anonymous-namespace'::<lambda0>>(_InIt,_InIt,const anonymous-namespace'::<lambda0>>(_InIt,_InIt,const _Ty &)' being compiled 1> with 1> [ 1> _InIt=std::_Vector_iterator<std::_Vector_val<std::tr1::shared_ptr<StringClass>,std::allocator<std::tr1::shared_ptr<StringClass>>>>, 1>
_Myvec=std::_Vector_val<std::tr1::shared_ptr<StringClass>,std::allocator<std::tr1::shared_ptr<StringClass>>>, 1> _Ty=

Answer 1

你想要使用find_if,而不是find.Find搜索值,find_if获取谓词.