ceph/src/boost/libs/metaparse/doc/digit_to_int_c.qbk

   1 [#digit_to_int_c]
   2 [section digit_to_int_c]
   3
   4 [h1 Synopsis]
   5
   6   namespace util
   7   {
   8     template <char D>
   9     struct digit_to_int_c;
  10   }
  11
  12 This is a template class similar to a [link metafunction template metafunction]
  13 but taking a `char` value as argument.
  14
  15 [table Arguments
  16   [[Name] [Type]]
  17   [[`D`]  [character value]]
  18 ]
  19
  20 [h1 Description]
  21
  22 Converts a character containing a value in the range `['0'..'9']` to an integer.
  23
  24 [h1 Return value]
  25
  26 It returns a [link boxed_value boxed] integer value.
  27
  28 [h1 Header]
  29
  30   #include <boost/metaparse/util/digit_to_int_c.hpp>
  31
  32 [h1 Expression semantics]
  33
  34 The following pairs of expressions are equivalent
  35
  36   digit_to_int_c<'0'>::type
  37   boost::mpl::int_<0>
  38
  39   digit_to_int_c<'9'>::type
  40   boost::mpl::int_<9>
  41
  42 [h1 Example]
  43
  44   #include <boost/metaparse/util/digit_to_int_c.hpp>
  45
  46   using namespace boost::metaparse;
  47
  48   static_assert(
  49     util::digit_to_int_c<'0'>::type::value == 0,
  50     "it should convert a character to the corresponding integer value"
  51   );
  52
  53   static_assert(
  54     util::digit_to_int_c<'3'>::type::value == 3,
  55     "it should convert a character to the corresponding integer value"
  56   );
  57
  58   static_assert(
  59     util::digit_to_int_c<'9'>::type::value == 9,
  60     "it should convert a character to the corresponding integer value"
  61   );
  62
  63 [endsect]
  64