numeric_limits

This class is specialized for each of the fundamental types, with its members returning or set to the different values that define the properties that type has in the specific platform in which it compiles.

For all the other types (non-fundamental types) a specialization of this class should not exist.

The non-specialized class is defined as:

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template <class T> class numeric_limits { public: static const bool is_specialized = false; static T min() throw(); static T max() throw(); static const int digits = 0; static const int digits10 = 0; static const bool is_signed = false; static const bool is_integer = false; static const bool is_exact = false; static const int radix = 0; static T epsilon() throw(); static T round_error() throw(); static const int min_exponent = 0; static const int min_exponent10 = 0; static const int max_exponent = 0; static const int max_exponent10 = 0; static const bool has_infinity = false; static const bool has_quiet_NaN = false; static const bool has_signaling_NaN = false; static const float_denorm_style has_denorm = denorm absent; static const bool has_denorm_loss = false; static T infinity() throw(); static T quiet_NaN() throw(); static T signalign_NaN() throw(); static T denorm_min() throw(); static const bool is_iec559 = false; static const bool is_bounded = false; static const bool is_modulo = false; static const bool traps = false; static const bool tinyness_before = false; static const float_round_style round_style = round_toward_zero; }

A specialization exists for each of the fundamental types: bool, char, signed char, unsigned char, wchar_t, short, unsigned short, int,unsigned int, long, unsigned long, float, double and long double. These specializations define the specific values for the differentstatic const members, and all have is_specialized defined as true.

출처 : http://www.cplusplus.com/reference/std/limits/numeric_limits/