固定宽度整数类型的整数文字

Question

对于像这样的固定宽度整数类型的整数文字是否有一些 c++ 建议？

// i's type is unsigned int
auto i = 10u;
// j's type is uint32_t
auto j = 10u32;

Answer 1

是：P1280R0 整数宽度文字（2018 年 10 月 5 日发布）。

它提出了以下文字：

namespace std::inline literals::inline integer_literals {
  constexpr uint64_t operator ""u64 (unsigned long long arg);
  constexpr uint32_t operator ""u32 (unsigned long long arg);
  constexpr uint16_t operator ""u16 (unsigned long long arg);
  constexpr uint8_t operator ""u8 (unsigned long long arg);

  constexpr int64_t operator ""i64 (unsigned long long arg);
  constexpr int32_t operator ""i32 (unsigned long long arg);
  constexpr int16_t operator ""i16 (unsigned long long arg);
  constexpr int8_t operator ""i8 (unsigned long long arg);
}

以及它的更新P1280R1，“将返回类型修改为实际上是[u]int_leastXX_t和朋友。这是为了确保我们实际上正在替换[U]INTxx_C宏，因为它们返回一个[u]int_leastXX_t”：

namespace std::inline literals::inline integer_literals {
  constexpr uint_least64_t operator ""u64 (unsigned long long arg);
  constexpr uint_least32_t operator ""u32 (unsigned long long arg);
  constexpr uint_least16_t operator ""u16 (unsigned long long arg);
  constexpr uint_least8_t operator ""u8 (unsigned long long arg);

  constexpr int_least64_t operator ""i64 (unsigned long long arg);
  constexpr int_least32_t operator ""i32 (unsigned long long arg);
  constexpr int_least16_t operator ""i16 (unsigned long long arg);
  constexpr int_least8_t operator ""i8 (unsigned long long arg);
}

有一个 2019-06-12 更新P1280R2使文字consteval而不是constexpr.