編譯錯誤，由於輸出容器對集合容器選擇錯誤

Question

template < class ProteinTypeInfo > 
class T_PP_edge{ 
private: 
    std::pair<ProteinTypeInfo, ProteinTypeInfo> paired_info; 
    unsigned priority; 

public: 
// the constructor stores the Protein types in lexico ordering 
    T_PP_edge(ProteinTypeInfo one, ProteinTypeInfo two){ 
    if (one<two) {paired_info.first = one; paired_info.second = two; } 
    else   {paired_info.first = two; paired_info.second = one; } 
    priority = 0; 
    } 

    T_PP_edge& operator=(T_PP_edge& other){ 
    priority = other.priority; 
    paired_info.first = other.paired_info.first; 
    paired_info.second = other.paired_info.second; 
    return *this ; 
    } 

    bool operator<(const T_PP_edge& a)const{ 
    if((*this).paired_info.first < a.paired_info.first) return true; 
    else if((*this).paired_info.second < a.paired_info.second) return true; 
    else return false; 
    } 

    const std::pair<ProteinTypeInfo, ProteinTypeInfo>& get_paired_info()const{ 
    return paired_info;} 

unsigned get_priority()const{return priority;} 
void set_priority(unsigned p) {priority = p;} 
}; 

// The lexico ordering used to compare pairs of proteins 


template < class ProteinTypeInfo > 
struct T_PP_edge_lexico_cmp{ 
public: 
typedef T_PP_edge<ProteinTypeInfo> PP_edge; 
bool operator()(const PP_edge& a, const PP_edge& b)const{ 
if(a.get_paired_info().first < b.get_paired_info().first) return true; 
else if(a.get_paired_info().second < b.get_paired_info().second) return true; 
else return false; 
} 

}; 

typedef std::string Protein_type; 
typedef T_PP_edge<Protein_type> PP_edge; 
typedef T_PP_edge_lexico_cmp<Protein_type> PP_edge_lexico_cmp; 

int main(){ 
    typedef std::set<PP_edge, PP_edge_lexico_cmp> Edge_set; 
    typedef Edge_set::iterator set_iterator; 
    Edge_set edgeP_set, edgeR_set; 
    PP_edge e1("aa", "bb"), e2("aa", "cc"), e3("bb", "cc"); 
    PP_edge e4("aa", "dd"), e5("aa", "cc"), e6("bb", "cc"); 
    edgeP_set.insert(e1); edgeP_set.insert(e2); edgeP_set.insert(e3); 
    edgeR_set.insert(e4); edgeR_set.insert(e5); edgeR_set.insert(e6); 
    Edge_set result; 
    std::set_intersection(edgeP_set.begin(), edgeP_set.end(), edgeR_set.begin(), 
    edgeR_set.end(), result.begin()); 
    set_iterator itb = result.begin(), ite = result.end(); 

    for(; itb != ite; ++itb) 
    std::cout << itb->get_paired_info().first << "-" << itb->get_paired_info().second << "\n"; 

    return 0; 
    }    

注意：包含set_intersection函數的算法。

以上代碼給出編譯以下錯誤：

g++ test_code.cpp 
In file included from /usr/lib/gcc/i686-redhat-linux/4.5.1/../../../../include/c++/4.5.1/algorithm:63:0, 
       from test_code.cpp:4: 
/usr/lib/gcc/i686-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/stl_algo.h: In function ‘_OIter std::set_intersection(_IIter1, _IIter1, _IIter2, _IIter2, _OIter) [with _IIter1 = std::_Rb_tree_const_iterator<T_PP_edge<std::basic_string<char> > >, _IIter2 = std::_Rb_tree_const_iterator<T_PP_edge<std::basic_string<char> > >, _OIter = std::_Rb_tree_const_iterator<T_PP_edge<std::basic_string<char> > >]’: 
test_code.cpp:79:111: instantiated from here 
/usr/lib/gcc/i686-redhat-linux/4.5.1/../../../../include/c++/4.5.1/bits/stl_algo.h:5648:6: error: no match for ‘operator=’ in ‘__result.std::_Rb_tree_const_iterator<_Tp>::operator* [with _Tp = T_PP_edge<std::basic_string<char> >, const _Tp& = const T_PP_edge<std::basic_string<char> >&]() = __first1.std::_Rb_tree_const_iterator<_Tp>::operator* [with _Tp = T_PP_edge<std::basic_string<char> >, const _Tp& = const T_PP_edge<std::basic_string<char> >&]()’ 
test_code.cpp:21:14: note: candidate is: T_PP_edge<ProteinTypeInfo>& T_PP_edge<ProteinTypeInfo>::operator=(T_PP_edge<ProteinTypeInfo>&) [with ProteinTypeInfo = std::basic_string<char>, T_PP_edge<ProteinTypeInfo> = T_PP_edge<std::basic_string<char> >] 

Compilation exited abnormally with code 1 at Mon Nov 26 21:28:38 

我懷疑這可能是由於在賦值操作符常量不正確。請幫助我。謝謝。

Answer 1

result.begin()不是set_intersection所預期的OutputIterator。

使用

std::inserter(result, result.end()) 

即使result.begin()會制定出它會通常只是段錯誤。無需預留足夠的內存即可使用std::vector進行試用。

而且，請您爲了您的讀者：擺脫空白。使用有意義的空白來顯示程序的邏輯流程。

此外，您的operator=是不必要的。它與默認生成的一樣。