這個坑其實我早就知道，只不過是沒有這個數據就會自動創建而已，頂多是一些錯誤數據而已，今天竟然出現了編譯錯誤！！！我特么還以為是構造函數的問題，查了一小時。我平時map用的很少，都是unordered_map，但是如果數據量小，哈希的效率還沒有紅黑樹高，我就換了map，開始的時候看到源碼中用的中括號，我就用了，也過了，就沒當回事，后來自己大改，編譯錯誤就出現了。
報的這個錯誤

In instantiation of ‘std::pair<_T1, _T2>::pair(std::tuple<_Args1 ...>&, std::tuple<_Args2 ...>&, std::_Index_tuple<_Indexes1 ...>, std::_Index_tuple<_Indexes2 ...>) [with _Args1 = {const int&}; unsigned int ..._Indexes1 = {0u}; _Args2 = {}; unsigned int ..._Indexes2 = {}; _T1 = const int; _T2 = thread_graphic]’: /opt/hisi-linux/x86-arm/arm-himix200-linux/arm-linux-gnueabi/include/c++/6.3.0/tuple:1575:63: required from ‘std::pair<_T1, _T2>::pair(std::piecewise_construct_t, std::tuple<_Args1 ...>, std::tuple<_Args2 ...>) [with _Args1 = {const int&}; _Args2 = {}; _T1 = const int; _T2 = thread_graphic]’ /opt/hisi-linux/x86-arm/arm-himix200-linux/arm-linux-gnueabi/include/c++/6.3.0/ext/new_allocator.h:120:4: required from ‘void __gnu_cxx::new_allocator<_Tp>::construct(_Up*, _Args&& ...) [with _Up = std::pair<const int, thread_graphic>; _Args = {const std::piecewise_construct_t&, std::tuple<const int&>, std::tuple<>}; _Tp = std::_Rb_tree_node<std::pair<const int, thread_graphic> >]’ /opt/hisi-linux/x86-arm/arm-himix200-linux/arm-linux-gnueabi/include/c++/6.3.0/bits/alloc_traits.h:455:4: required from ‘static void std::allocator_traits<std::allocator<_CharT> >::construct(std::allocator_traits<std::allocator<_CharT> >::allocator_type&, _Up*, _Args&& ...) [with _Up = std::pair<const int, thread_graphic>; _Args = {const std::piecewise_construct_t&, std::tuple<const int&>, std::tuple<>}; _Tp = std::_Rb_tree_node<std::pair<const int, thread_graphic> >; std::allocator_traits<std::allocator<_CharT> >::allocator_type = std::allocator<std::_Rb_tree_node<std::pair<const int, thread_graphic> > >]’ /opt/hisi-linux/x86-arm/arm-himix200-linux/arm-linux-gnueabi/include/c++/6.3.0/bits/stl_tree.h:543:32: required from ‘void std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_construct_node(std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Link_type, _Args&& ...) [with _Args = {const std::piecewise_construct_t&, std::tuple<const int&>, std::tuple<>}; _Key = int; _Val = std::pair<const int, thread_graphic>; _KeyOfValue = std::_Select1st<std::pair<const int, thread_graphic> >; _Compare = std::less<int>; _Alloc = std::allocator<std::pair<const int, thread_graphic> >; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Link_type = std::_Rb_tree_node<std::pair<const int, thread_graphic> >*]’ /opt/hisi-linux/x86-arm/arm-himix200-linux/arm-linux-gnueabi/include/c++/6.3.0/bits/stl_tree.h:560:4: required from ‘std::_Rb_tree_node<_Val>* std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_create_node(_Args&& ...) [with _Args = {const std::piecewise_construct_t&, std::tuple<const int&>, std::tuple<>}; _Key = int; _Val = std::pair<const int, thread_graphic>; _KeyOfValue = std::_Select1st<std::pair<const int, thread_graphic> >; _Compare = std::less<int>; _Alloc = std::allocator<std::pair<const int, thread_graphic> >; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_Link_type = std::_Rb_tree_node<std::pair<const int, thread_graphic> >*]’ /opt/hisi-linux/x86-arm/arm-himix200-linux/arm-linux-gnueabi/include/c++/6.3.0/bits/stl_tree.h:2196:64: required from ‘std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_emplace_hint_unique(std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::const_iterator, _Args&& ...) [with _Args = {const std::piecewise_construct_t&, std::tuple<const int&>, std::tuple<>}; _Key = int; _Val = std::pair<const int, thread_graphic>; _KeyOfValue = std::_Select1st<std::pair<const int, thread_graphic> >; _Compare = std::less<int>; _Alloc = std::allocator<std::pair<const int, thread_graphic> >; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::iterator = std::_Rb_tree_iterator<std::pair<const int, thread_graphic> >; std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::const_iterator = std::_Rb_tree_const_iterator<std::pair<const int, thread_graphic> >]’ /opt/hisi-linux/x86-arm/arm-himix200-linux/arm-linux-gnueabi/include/c++/6.3.0/bits/stl_map.h:483:8: required from ‘std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = int; _Tp = thread_graphic; _Compare = std::less<int>; _Alloc = std::allocator<std::pair<const int, thread_graphic> >; std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type = thread_graphic; std::map<_Key, _Tp, _Compare, _Alloc>::key_type = int]’

我特喵啥也看不懂，結果后來用了find和insert，一下就好了，具體原因沒深究，估計要看一下源碼才知道了，這個問題先記下吧

總結

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