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ä½ç½®ï¼šé¦–页 > C++ å‚考手册 >C++ æ ‡å‡†åº“å¤´æ–‡ä»¶ > æ ‡å‡†åº“å¤´æ–‡ä»¶ <limits>
æ ‡å‡†åº“å¤´æ–‡ä»¶ <limits>
æ¤å¤´æ–‡ä»¶æ˜¯ç±»åž‹æ”¯æŒåº“的一部分。
声明
| æ供查询所有基础数值类型的性质的接å£ã€‚ (类模æ¿) | |
| 指示浮点èˆå…¥æ¨¡å¼ (枚举) | |
| 指示浮点éžè§„æ ¼åŒ–æ¨¡å¼ (枚举) |
概è¦
namespace std { template<class T> class numeric_limits; Â enum float_round_style { round_indeterminate = -1, round_toward_zero = 0, round_to_nearest = 1, round_toward_infinity = 2, round_toward_neg_infinity = 3, }; Â enum float_denorm_style { denorm_indeterminate = -1, denorm_absent = 0, denorm_present = 1 }; Â Â template<> class numeric_limits<bool>; Â template<> class numeric_limits<char>; template<> class numeric_limits<signed char>; template<> class numeric_limits<unsigned char>; template<> class numeric_limits<char8_t>; template<> class numeric_limits<char16_t>; template<> class numeric_limits<char32_t>; template<> class numeric_limits<wchar_t>; Â template<> class numeric_limits<short>; template<> class numeric_limits<int>; template<> class numeric_limits<long>; template<> class numeric_limits<long long>; template<> class numeric_limits<unsigned short>; template<> class numeric_limits<unsigned int>; template<> class numeric_limits<unsigned long>; template<> class numeric_limits<unsigned long long>; Â template<> class numeric_limits<float>; template<> class numeric_limits<double>; template<> class numeric_limits<long double>; }
ç±»æ¨¡æ¿ std::numeric_limits
template<class T> class numeric_limits { public: static constexpr bool is_specialized = false; Â static constexpr T min() noexcept { return T(); } static constexpr T max() noexcept { return T(); } static constexpr T lowest() noexcept { return T(); } Â static constexpr int digits = 0; static constexpr int digits10 = 0; static constexpr int max_digits10 = 0; Â static constexpr bool is_signed = false; static constexpr bool is_integer = false; static constexpr bool is_exact = false; static constexpr int radix = 0; static constexpr T epsilon() noexcept { return T(); } static constexpr T round_error() noexcept { return T(); } Â static constexpr int min_exponent = 0; static constexpr int min_exponent10 = 0; static constexpr int max_exponent = 0; static constexpr int max_exponent10 = 0; Â static constexpr bool has_infinity = false; static constexpr bool has_quiet_NaN = false; static constexpr bool has_signaling_NaN = false; static constexpr float_denorm_style has_denorm = denorm_absent; static constexpr bool has_denorm_loss = false; static constexpr T infinity() noexcept { return T(); } static constexpr T quiet_NaN() noexcept { return T(); } static constexpr T signaling_NaN() noexcept { return T(); } static constexpr T denorm_min() noexcept { return T(); } Â static constexpr bool is_iec559 = false; static constexpr bool is_bounded = false; static constexpr bool is_modulo = false; Â static constexpr bool traps = false; static constexpr bool tinyness_before = false; static constexpr float_round_style round_style = round_toward_zero; Â };
std::numeric_limits<bool> 特化
template<> class numeric_limits<bool> { public: static constexpr bool is_specialized = true; Â static constexpr bool min() noexcept { return false; } static constexpr bool max() noexcept { return true; } static constexpr bool lowest() noexcept { return false; } Â static constexpr int digits = 1; static constexpr int digits10 = 0; static constexpr int max_digits10 = 0; Â static constexpr bool is_signed = false; static constexpr bool is_integer = true; static constexpr bool is_exact = true; static constexpr int radix = 2; static constexpr bool epsilon() noexcept { return 0; } static constexpr bool round_error() noexcept { return 0; } Â static constexpr int min_exponent = 0; static constexpr int min_exponent10 = 0; static constexpr int max_exponent = 0; static constexpr int max_exponent10 = 0; Â static constexpr bool has_infinity = false; static constexpr bool has_quiet_NaN = false; static constexpr bool has_signaling_NaN = false; static constexpr float_denorm_style has_denorm = denorm_absent; static constexpr bool has_denorm_loss = false; static constexpr bool infinity() noexcept { return 0; } static constexpr bool quiet_NaN() noexcept { return 0; } static constexpr bool signaling_NaN() noexcept { return 0; } static constexpr bool denorm_min() noexcept { return 0; } Â static constexpr bool is_iec559 = false; static constexpr bool is_bounded = true; static constexpr bool is_modulo = false; Â static constexpr bool traps = false; static constexpr bool tinyness_before = false; static constexpr float_round_style round_style = round_toward_zero; Â };