我有一个映射,其值为std :: pair。无法设置std :: pair std :: map的迭代器
编译器抱怨试图建立一个迭代时,按如下,但我不明白为什么:
src/DBConnector.cpp: In member function ‘int DBConnector::createGenericInsert(std::string, std::map<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<int, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<int, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > > >, std::string&)’: src/DBConnector.cpp:354: error: no match for ‘operator=’ in ‘l_oIterEnd = p_mapValues.std::map<_Key, _Tp, _Compare, _Alloc>::end with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Tp = std::pair<int, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<int, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >’ /usr/include/c++/4.4/bits/stl_map.h:251: note: candidates are: std::map<_Key, _Tp, _Compare, _Alloc>& std::map<_Key, _Tp, _Compare, _Alloc>::operator=(const std::map<_Key, _Tp, _Compare, _Alloc>&) [with _Key = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, _Tp = std::pair<int, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Compare = std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, _Alloc = std::allocator<std::pair<const std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<int, std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >]
我的功能是是:
int DBConnector::createGenericInsert (std::string p_sTable , std::map<std::string , std::pair<int,std::string> > p_mapValues , std::string & po_sInsert) {
std::map<std::string,std::pair<int,std::string> > l_oIter;
std::map<std::string,std::pair<int,std::string> > l_oIterEnd;
std::string s_Fieldnames;
l_oIterEnd = p_mapValues.end(); // This is line 354
l_oIter = p_mapValues.begin();
s_Fieldnames += l_oIter.first();
...
}
这里有什么问题吗?地图是否可以包含std :: pairs? (此外,地图是否可以包含不同类型的按键?)
你声明'l_oIter'为'std :: map',而不是一个迭代器... – Mat 2012-02-12 17:27:31