Question

我正在尝试插入我的智能指针，p_pointer指向foo类进入map，但程序无法编译。因此，我试图使用普通指针foo *，程序确实编译。到目前为止，我已经能够像普通指针一样使用p_pointer而没有任何问题，所以我很惊讶这不起作用。如果有人能向我解释为什么这不起作用......

*此外，我已经发布在这里，人们抱怨我的代码之前很乱。这次我使用了代码块功能＆＃34;格式化使用Astyle＆＃34;。如果这还不够好，请告诉我。

    #include <iostream>
    #include<map>
    #include<string>
    using namespace std;

    template <class T>
    class p_pointer
    {
    public:
        T* cp;
        size_t* refptr;

        size_t* counter()
        {
            return refptr;
        }
    //default constructor
        p_pointer():cp(0),refptr(new size_t(1)) {}
        p_pointer(T*t):cp(t),refptr(new size_t(1)) {}
    //copy constructor
        p_pointer (const p_pointer&s):cp(s.cp),refptr(s.refptr)
        {
            refptr=s.refptr;
            cp=s.cp;
            *refptr=*refptr+1;
        }
    //destructor
        ~p_pointer()
        {

            if(--*refptr==0)
            {
                delete cp;
                delete refptr;
            }
        }

    //assignment operator
        p_pointer&operator=(const p_pointer&s)
        {
            ++*s.refptr;
    //freeing the left hand size if it is the last one
            if(--*refptr==0)
            {
                delete cp;
                delete refptr;
            }
            cp=s.cp;
            refptr=s.refptr;
        }

        operator bool()
        {
            return cp;
        }

        T*&operator->()
        {
            if(cp)
                return cp;

            else throw std::runtime_error("uninitialized player");
        }

        T operator*()
        {
            if(cp)
                return *cp;
            else throw std::runtime_error("uninitialized player");
        }
    };

    class foo
    {};

 //Method 1(work)
    int main()
    {
        map<foo*,int> x;
        foo* y=new foo();
        x[y]=1;
    }

//Method 2 (does not work)

int main()
{
    map<p_pointer<foo>,int> x;
    p_pointer<foo> y=new foo();
    x[y]=1;
}

错误消息是：这是我第一次发布错误消息。我刚从构建消息中复制了所有内容并将其粘贴到此处。如果这不是最佳方式，请告诉我

|| === Build：在试用版821中调试（编译器：GNU GCC编译器）=== | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h ||实例化＆＃39; bool std :: less＆lt; _Tp＆gt; :: operator（）（const _Tp＆amp;，const _Tp＆amp;）const [with _Tp = p_pointer]＆＃39;：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_map.h | 498 |必需来自＆＃39; std :: map＆lt; _Key，_Tp，_Compare，_Alloc＆gt; :: mapped_type＆安培; std :: map＆lt; _Key，_Tp，_Compare，_ Alloc＆gt; :: operator []（const key_type＆amp;）[with _Key = p_pointer; _Tp = int; _Compare = std :: less＆gt ;; _Alloc = std :: allocator，int＆gt;取代; std :: map＆lt; _Key，_Tp，_Compare，_Alloc＆gt; :: mapped_type = int; std :: map＆lt; _Key，_Tp，_Compare，_Alloc＆gt; :: key_type = p_pointer]＆＃39; | C：\ trial 821 \ main.cpp | 80 |从这里要求| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |错误：不匹配＆＃39;运算符＆lt;＆＃39; （操作数类型是＆＃39; const p_pointer＆＃39;和＆＃39; const p_pointer＆＃39;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：候选人是：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：operator＆lt;（int，int）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：没有来自＆＃39; const p_pointer＆＃39;的参数2的已知转换到＆＃39; int＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_pair.h | 220 |注意：模板constexpr bool std :: operator＆lt;（const std :: pair＆lt; _T1，_T2＆gt; ＆amp;，const std :: pair＆lt; _T1，_T2＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_pair.h | 220 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源于＆＃39; const std :: pair＆lt; _T1，_T2＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_iterator.h | 298 |注意：模板bool std :: operator＆lt;（const std :: reverse_iterator＆lt; _Iterator＆gt;＆amp;， const std :: reverse_iterator＆lt; _Iterator＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_iterator.h | 298 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源自＆＃39; const std :: reverse_iterator＆lt; _Iterator＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_iterator.h | 348 |注意：模板bool std :: operator＆lt;（const std :: reverse_iterator＆lt; _Iterator＆gt;＆amp;， const std :: reverse_iterator＆lt; _IteratorR＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_iterator.h | 348 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源自＆＃39; const std :: reverse_iterator＆lt; _Iterator＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_iterator.h | 1072 |注意：模板bool std :: operator＆lt;（const std :: move_iterator＆lt; _Iterator＆gt;＆amp ;, const std :: move_iterator＆lt; _IteratorR＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_iterator.h | 1072 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源于＆＃39; const std :: move_iterator＆lt; _Iterator＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_iterator.h | 1078 |注意：模板bool std :: operator＆lt;（const std :: move_iterator＆lt; _Iterator＆gt;＆amp;， const std :: move_iterator＆lt; _Iterator＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_iterator.h | 1078 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源于＆＃39; const std :: move_iterator＆lt; _Iterator＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ basic_string.h | 2588 |注意：模板bool std :: operator＆lt;（const std :: basic_string＆lt; _CharT，_Traits，_Alloc＆gt ;＆amp;，const std :: basic_string＆lt; _CharT，_Traits，_Alloc＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ basic_string.h | 2588 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源自＆＃39; const std :: basic_string＆lt; _CharT，_Traits，_Alloc＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ basic_string.h | 2600 |注意：模板bool std :: operator＆lt;（const std :: basic_string＆lt; _CharT，_Traits，_Alloc＆gt ;＆amp;，const _CharT *）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ basic_string.h | 2600 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源自＆＃39; const std :: basic_string＆lt; _CharT，_Traits，_Alloc＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ basic_string.h | 2612 |注意：模板bool std :: operator＆lt;（const _CharT *，const std :: basic_string＆lt; _CharT ，_Traits，_Alloc＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ basic_string.h | 2612 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：不匹配的类型＆＃39; const _CharT *＆＃39;和＆＃39; p_pointer＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_tree.h | 980 |注意：模板bool std :: operator＆lt;（const std :: _ Rb_tree＆lt; _Key，_Val，_KeyOfValue ，_Compare，_ Alloc＆gt;＆amp;，const std :: _ Rb_tree＆lt; _Key，_Val，_KeyOfValue，_Compare，_Alloc＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_tree.h | 980 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源于＆＃39; const std :: _ Rb_tree＆lt; _Key，_Val，_KeyOfValue，_Compare，_ Alloc＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ array | 242 |注意：模板bool std :: operator＆lt;（const std :: array＆lt; _Tp，_Nm＆gt;＆amp;，const std :: array＆lt; _Tp，_Nm＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ array | 242 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源自＆＃39; const std :: array＆lt; _Tp，_Nm＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ tuple | 857 |注意：模板constexpr bool std :: operator＆lt;（const std :: tuple＆lt; _Args1 ...＆amp;＆amp; ，const std :: tuple＆lt; _Args2 ...＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ tuple | 857 |注意：模板参数扣除/替换失败： C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源于＆＃39; const std :: tuple＆lt; _Args1 ...＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_map.h | 1017 |注意：模板bool std :: operator＆lt;（const std :: map＆lt; _Key，_Tp，_Compare ，_Alloc＆gt;＆amp;，const std :: map＆lt; _Key，_Tp，_Compare，_Alloc＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_map.h | 1017 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源于＆＃39; const std :: map＆lt; _Key，_Tp，_Compare，_Alloc＆gt;＆＃39; | C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_multimap.h | 920 |注意：模板bool std :: operator＆lt;（const std :: multimap＆lt; _Key，_Tp，_Compare ，_Alloc＆gt;＆amp;，const std :: multimap＆lt; _Key，_Tp，_Compare，_Alloc＆gt;＆amp;）| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_multimap.h | 920 |注意：模板参数扣除/替换失败：| C：\ CodeBlocks \ MinGW \ lib \ gcc \ mingw32 \ 4.9.2 \ include \ c ++ \ bits \ stl_function.h | 371 |注意：＆＃39; const p_pointer＆＃39;不是源于＆＃39; const std :: multimap＆lt; _Key，_Tp，_Compare，_Alloc＆gt;＆＃39; | || ===构建失败：1个错误，3个警告（0分钟，0秒（秒））=== |

Answer 1

您的问题可以在错误消息中找到：no match for 'operator<' (operand types are 'const p_pointer' and 'const p_pointer')|。为了将map与自定义类型（在这种情况下为p_pointer）一起使用，该类型需要声明一个比较运算符<，用于对映射中的键进行排序。您需要实现<运算符，这应该可以解决此错误。（但是可能会出现其他错误以替换它。）

同样，我建议您只使用现有的std::shared_ptr，而不是自己重新实施，除非您有某些理由不这样做。

无法将智能指针插入地图

1 个答案: