std :: map

Question

的类内初始化我有这段代码不能在g ++下编译 - 4.9.1（我使用了命令“g ++ -c --std = C++ 11 map.cc “）

#include <map> 
#include <cstdint> 
class A { 
    std::map<uint8_t, uint8_t> b = std::map<uint8_t, uint8_t>(); 
}; 

编译时我收到以下错误：

map.cc:5:52: error: expected ‘;’ at end of member declaration 
    std::map<uint8_t, uint8_t> b = std::map<uint8_t, uint8_t>(); 
                ^
map.cc:5:52: error: declaration of ‘std::map<unsigned char, unsigned char> A::uint8_t’ [-fpermissive] 
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.9/include/stdint.h:9:0, 
       from /usr/include/c++/4.9/cstdint:41, 
       from /usr/include/c++/4.9/bits/char_traits.h:380, 
       from /usr/include/c++/4.9/string:40, 
       from /usr/include/c++/4.9/stdexcept:39, 
       from /usr/include/c++/4.9/array:38, 
       from /usr/include/c++/4.9/tuple:39, 
       from /usr/include/c++/4.9/bits/stl_map.h:63, 
       from /usr/include/c++/4.9/map:61, 
       from map.cc:1: 
/usr/include/stdint.h:48:24: error: changes meaning of ‘uint8_t’ from ‘typedef unsigned char uint8_t’ [-fpermissive] 
typedef unsigned char uint8_t; 
         ^
map.cc:5:59: error: expected unqualified-id before ‘>’ token 
    std::map<uint8_t, uint8_t> b = std::map<uint8_t, uint8_t>(); 
                 ^
map.cc:5:43: error: wrong number of template arguments (1, should be 4) 
    std::map<uint8_t, uint8_t> b = std::map<uint8_t, uint8_t>(); 
             ^
In file included from /usr/include/c++/4.9/map:61:0, 
       from map.cc:1: 
/usr/include/c++/4.9/bits/stl_map.h:96:11: error: provided for ‘template<class _Key, class _Tp, class _Compare, class _Alloc> class std::map’ 
    class map 
     ^

但是，如果我与诠释更换uint8_t，它编译罚款。

Answer 1

FWIW，如果你需要一个解决办法，下面的工作：

class A { 
    typedef std::map<uint8_t, uint8_t> B; 
    B b = B(); 
};