This header was originally in the C standard library as <float.h>
.
This header is part of the type support library, in particular it's part of the C numeric limits interface.
FLT_RADIX  the radix (integer base) used by the representation of all three floatingpoint types (macro constant) 
DECIMAL_DIG
(C++11)  conversion from long double to decimal with at least DECIMAL_DIG digits and back to long double is the identity conversion: this is the decimal precision required to serialize/deserialize a long double (see also std::numeric_limits::max_digits10 ) (macro constant) 
FLT_DECIMAL_DIGDBL_DECIMAL_DIGLDBL_DECIMAL_DIG
(C++17)  conversion from float/double/long double to decimal with at least FLT_DECIMAL_DIG /DBL_DECIMAL_DIG /LDBL_DECIMAL_DIG digits and back is the identity conversion: this is the decimal precision required to serialize/deserialize a floatingpoint value (see also std::numeric_limits::max_digits10 ). Defined to at least 6 , 10 , and 10 respectively, or 9 for IEEE float and 17 for IEEE double. (macro constant) 
FLT_MINDBL_MINLDBL_MIN  minimum normalized positive value of float, double and long double respectively (macro constant) 
FLT_TRUE_MINDBL_TRUE_MINLDBL_TRUE_MIN
(C++17)  minimum positive value of float, double and long double respectively (macro constant) 
FLT_MAXDBL_MAXLDBL_MAX  maximum finite value of float, double and long double respectively (macro constant) 
FLT_EPSILONDBL_EPSILONLDBL_EPSILON  difference between 1.0 and the next representable value for float, double and long double respectively (macro constant) 
FLT_DIGDBL_DIGLDBL_DIG  number of decimal digits that are guaranteed to be preserved in text → float/double/long double → text roundtrip without change due to rounding or overflow (see std::numeric_limits::digits10 for explanation) (macro constant) 
FLT_MANT_DIGDBL_MANT_DIGLDBL_MANT_DIG  number of base FLT_RADIX digits that can be represented without losing precision for float, double and long double respectively (macro constant) 
FLT_MIN_EXPDBL_MIN_EXPLDBL_MIN_EXP  minimum negative integer such that FLT_RADIX raised by power one less than that integer is a normalized float, double and long double respectively (macro constant) 
FLT_MIN_10_EXPDBL_MIN_10_EXPLDBL_MIN_10_EXP  minimum negative integer such that 10 raised to that power is a normalized float, double and long double respectively (macro constant) 
FLT_MAX_EXPDBL_MAX_EXPLDBL_MAX_EXP  maximum positive integer such that FLT_RADIX raised by power one less than that integer is a representable finite float, double and long double respectively (macro constant) 
FLT_MAX_10_EXPDBL_MAX_10_EXPLDBL_MAX_10_EXP  maximum positive integer such that 10 raised to that power is a representable finite float, double and long double respectively (macro constant) 
default rounding mode of floatingpoint arithmetic (macro constant) 

(C++11)  specifies in what precision all arithmetic operations are done (macro constant) 
FLT_HAS_SUBNORMDBL_HAS_SUBNORMLDBL_HAS_SUBNORM
(C++17)  specifies whether the type supports subnormal (denormal) numbers:1 – indeterminable, 0 – absent, 1 – present (macro constant) 
#define FLT_ROUNDS /* see definition */ #define FLT_EVAL_METHOD /* see definition */ #define FLT_HAS_SUBNORM /* see definition */ #define DBL_HAS_SUBNORM /* see definition */ #define LDBL_HAS_SUBNORM /* see definition */ #define FLT_RADIX /* see definition */ #define FLT_MANT_DIG /* see definition */ #define DBL_MANT_DIG /* see definition */ #define LDBL_MANT_DIG /* see definition */ #define FLT_DECIMAL_DIG /* see definition */ #define DBL_DECIMAL_DIG /* see definition */ #define LDBL_DECIMAL_DIG /* see definition */ #define DECIMAL_DIG /* see definition */ #define FLT_DIG /* see definition */ #define DBL_DIG /* see definition */ #define LDBL_DIG /* see definition */ #define FLT_MIN_EXP /* see definition */ #define DBL_MIN_EXP /* see definition */ #define LDBL_MIN_EXP /* see definition */ #define FLT_MIN_10_EXP /* see definition */ #define DBL_MIN_10_EXP /* see definition */ #define LDBL_MIN_10_EXP /* see definition */ #define FLT_MAX_EXP /* see definition */ #define DBL_MAX_EXP /* see definition */ #define LDBL_MAX_EXP /* see definition */ #define FLT_MAX_10_EXP /* see definition */ #define DBL_MAX_10_EXP /* see definition */ #define LDBL_MAX_10_EXP /* see definition */ #define FLT_MAX /* see definition */ #define DBL_MAX /* see definition */ #define LDBL_MAX /* see definition */ #define FLT_EPSILON /* see definition */ #define DBL_EPSILON /* see definition */ #define LDBL_EPSILON /* see definition */ #define FLT_MIN /* see definition */ #define DBL_MIN /* see definition */ #define LDBL_MIN /* see definition */ #define FLT_TRUE_MIN /* see definition */ #define DBL_TRUE_MIN /* see definition */ #define LDBL_TRUE_MIN /* see definition */
C documentation for Limits of floatingpoint types 
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