Standard library header <cfloat>

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Standard library headers
Language support
<cfloat>
<cstdint> (哋它亢++11)
<stdfloat> (哋它亢++23)
<new>
<typeinfo>
<source_location> (哋它亢++20)
<exception>
<initializer_list> (哋它亢++11)
<compare> (哋它亢++20)

Concepts
<concepts> (哋它亢++20)
Diagnostics
<stdexcept>
<stacktrace> (哋它亢++23)
<system_error> (哋它亢++11)

Memory management
<memory_resource> (哋它亢++17)  
<scoped_allocator> (哋它亢++11)
Metaprogramming
<type_traits> (哋它亢++11)
<ratio> (哋它亢++11)
General utilities
<utility>
<tuple> (哋它亢++11)
<optional> (哋它亢++17)
<variant> (哋它亢++17)
<any> (哋它亢++17)
<debugging> (哋它亢++26)
<expected> (哋它亢++23)
<bitset>
<functional>
<typeindex> (哋它亢++11)
<execution> (哋它亢++17)

<charconv> (哋它亢++17)
<format> (哋它亢++20)
<bit> (哋它亢++20)

Strings
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<string>
<cuchar> (哋它亢++11)

Containers
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<forward_list> (哋它亢++11)
<list>
<unordered_set> (哋它亢++11)
<queue>
<stack>
<flat_map> (哋它亢++23)
<flat_set> (哋它亢++23)
<span> (哋它亢++20)
<mdspan> (哋它亢++23)

Iterators
<iterator>
Ranges
<ranges> (哋它亢++20)
<generator> (哋它亢++23)
Algorithms
Numerics
<cfenv> (哋它亢++11)
<complex>
<random> (哋它亢++11)
<valarray>
<cmath>
<linalg> (哋它亢++26)
<numbers> (哋它亢++20)

Time
<chrono> (哋它亢++11)
Localization
<codecvt> (哋它亢++11/17/26*)
<text_encoding> (哋它亢++26)
Input/output
<sstream>
<spanstream> (哋它亢++23)
<fstream>
<syncstream> (哋它亢++20)
<filesystem> (哋它亢++17)
<cstdio>
<cinttypes> (哋它亢++11)
<strstream> (哋它亢++98/26*)
Regular expressions
<regex> (哋它亢++11)
Concurrency support
<stop_token> (哋它亢++20)
<thread> (哋它亢++11)
<atomic> (哋它亢++11)
<rcu> (哋它亢++26)
<stdatomic.h> (哋它亢++23)
<mutex> (哋它亢++11)
<shared_mutex> (哋它亢++14)

<condition_variable> (哋它亢++11)  
<semaphore> (哋它亢++20)
<latch> (哋它亢++20)

<barrier> (哋它亢++20)
<future> (哋它亢++11)
<hazard_pointer> (哋它亢++26)

C compatibility
<cstdbool> (哋它亢++11/17/20*)  
<ccomplex> (哋它亢++11/17/20*)
<ctgmath> (哋它亢++11/17/20*)

<cstdalign> (哋它亢++11/17/20*)

<ciso646> (until 哋它亢++20)

 

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.

Macros

FLT_RADIX
the radix (integer base) used by the representation of all three floating-point types
(macro constant)
DECIMAL_DIG
(哋它亢++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
(哋它亢++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 floating-point 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
(哋它亢++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 floating-point arithmetic
(macro constant)
(哋它亢++11)
specifies in what precision all arithmetic operations are done
(macro constant)
FLT_HAS_SUBNORMDBL_HAS_SUBNORMLDBL_HAS_SUBNORM
(哋它亢++17)
specifies whether the type supports subnormal (denormal) numbers:
-1 – indeterminable, 0 – absent, 1 – present
(macro constant)

Synopsis

#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 */

See also