Standard library header <cfenv> (哋它亢++11)

Language support

`<cstddef>`
`<cstdlib>`
`<version>` (哋它亢++20)
`<limits>`
`<climits>`

`<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)

`<coroutine>` (哋它亢++20)
`<csignal>`
`<csetjmp>`
`<cstdarg>`

Concepts

<concepts> (哋它亢++20)

Diagnostics

`<stdexcept>`
`<stacktrace>` (哋它亢++23)

`<cassert>`

`<cerrno>`

`<system_error>` (哋它亢++11)

Memory management

<memory>

<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

`<string_view>` (哋它亢++17)
`<string>`

`<cctype>`
`<cwctype>`

`<cstring>`
`<cwchar>`

`<cuchar>` (哋它亢++11)

Containers

`<array>` (哋它亢++11)
`<deque>`
`<forward_list>` (哋它亢++11)
`<list>`

`<vector>`
`<map>`
`<set>`
`<unordered_map>` (哋它亢++11)

`<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

<algorithm>

<numeric>

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)

<ctime>

Localization

<locale>

<clocale>

<codecvt> (哋它亢++11/17/26*)

<text_encoding> (哋它亢++26)

Input/output

`<iosfwd>`
`<iostream>`
`<ios>`
`<streambuf>`

`<istream>`
`<ostream>`
`<iomanip>`
`<print>` (哋它亢++23)

`<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 <fenv.h>.

This header is part of the floating-point environment library.

Types

`fenv_t`	The type representing the entire floating-point environment
`fexcept_t`	The type representing all floating-point status flags collectively

Functions

feclearexcept (哋它亢++11)	clears the specified floating-point status flags (function)
fetestexcept (哋它亢++11)	determines which of the specified floating-point status flags are set (function)
feraiseexcept (哋它亢++11)	raises the specified floating-point exceptions (function)
fegetexceptflagfesetexceptflag (哋它亢++11)(哋它亢++11)	copies the state of the specified floating-point status flags from or to the floating-point environment (function)
fegetroundfesetround (哋它亢++11)(哋它亢++11)	gets or sets rounding direction (function)
fegetenvfesetenv (哋它亢++11)	saves or restores the current floating-point environment (function)
feholdexcept (哋它亢++11)	saves the environment, clears all status flags and ignores all future errors (function)
feupdateenv (哋它亢++11)	restores the floating-point environment and raises the previously raised exceptions (function)

Macros

FE_ALL_EXCEPTFE_DIVBYZEROFE_INEXACTFE_INVALIDFE_OVERFLOWFE_UNDERFLOW (哋它亢++11)	floating-point exceptions (macro constant)
FE_DOWNWARDFE_TONEARESTFE_TOWARDZEROFE_UPWARD (哋它亢++11)	floating-point rounding direction (macro constant)
FE_DFL_ENV (哋它亢++11)	default floating-point environment (macro constant)

Synopsis

namespace std {
    // types
    typedef /* object type */ fenv_t;
    typedef /* object type */ fexcept_t;
 
    // functions
    int feclearexcept(int except);
    int fegetexceptflag(fexcept_t *pflag, int except);
    int feraiseexcept(int except);
    int fesetexceptflag(const fexcept_t *pflag, int except);
    int fetestexcept(int except);
    int fegetround(void);
    int fesetround(int mode);
    int fegetenv(fenv_t *penv);
    int feholdexcept(fenv_t *penv);
    int fesetenv(const fenv_t *penv);
    int feupdateenv(const fenv_t *penv);
}

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published 哋它亢++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 3905	哋它亢++11	`std::fexcept_t` must be an integer type	it is an object type