c++ - How to get smallest variable with C++11 user defined literals -

I am looking at some new features of C ++ 11 and are very impressed with some of them, especially user defined Verbatim

This allows you to define the written words of 999_something , where to generate some control 999 For now, it is not being used:

  #define MEG * 1024 * 1024 int ten_meg = 10 m;   
 I was thinking that it would be good to apply a large number of underscores, such as  1_000_000_blah  which would conform to Pearl's readability, although this idea is somewhat readable I feel quite humorous: -)  
 This will also be easy for binary values ​​like  1101_1110_b  and  0011_0011_1100_1111_b .  
 Obviously due to the  _  characters, they will need the raw mode type, the string must be processed, and I am fine with it.  
 I can not   find out how to distribute a different type depending on operand size, for example:  
  1101_1110_b   
 should be given a  char  (value is  char) is 8-bit unless:  
  0011_0011_1100_1111_b   
 will deliver a 16-bit type.  
 I can get the length of the operation from the literal operator function  operator ""  Only (by counting the numbers of digits), but return Raksha Function is being fixed, so I can not return a different type on it.  
 Is it a suffix  _b  within the defined type of user , Or I need to manually support a different type of partition ( _b8 ,  _b16  and so on) and provide more duplicate functions ?   
 
 
 You should know Oh, your string size, and the only way to achieve this is that  sizeof ... . You should be able to get what you want with a variadic template  operator ":  
  #include & lt; cstdint & gt; # Include & Lt; type_traits & gt; template & lt; char ... string & gt; auto operator "" _b () - & gt; Typename std :: conditional & lt; sizeof ... (string) & lt; = 8, Uint8_t, typename std :: conditional & lt; sizeof ... (string) & lt; = 16, uint16_t, uint32_t & gt; :: Type & gt; ::   
 and here There is a test case:  
  int main () {auto a = 10000001_b; auto B = 100000001_b; std :: cout  std :: conditional  machinery is quite ugly You probably can do some work with  boost :: mpl :: vector ,  boost :: mpl :: at  and some arithmetic operations.