Standard library header <limits>

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

Standard library headers

Language support <cfloat> <climits> <compare>(C++20) <contracts>(C++26) <coroutine>(C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint>(C++11) <cstdlib> <exception> <initializer_list>(C++11)    <limits> <new> <source_location>(C++20) <stdfloat>(C++23) <typeinfo> <version>(C++20) Concepts <concepts>(C++20) Diagnostics <cassert> <cerrno> <debugging>(C++26) <stacktrace>(C++23) <stdexcept> <system_error>(C++11) Memory management <memory> <memory_resource>(C++17) <scoped_allocator>(C++11) Metaprogramming <type_traits>(C++11) <ratio>(C++11)

General utilities <any>(C++17) <bitset> <bit>(C++20) <charconv>(C++17) <expected>(C++23) <format>(C++20) <functional> <optional>(C++17) <stdbit.h>(C++26) <tuple>(C++11) <typeindex>(C++11) <utility> <variant>(C++17) Containers <array>(C++11) <deque> <flat_map>(C++23) <flat_set>(C++23) <forward_list>(C++11) <hive>(C++26) <inplace_vector>(C++26)    <list> <map> <mdspan>(C++23) <queue> <set> <span>(C++20) <stack> <unordered_map>(C++11) <unordered_set>(C++11) <vector> Iterators <iterator> Ranges <generator>(C++23) <ranges>(C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar>(C++11) <cwchar> <cwctype> <string_view>(C++17) <string> Text processing <clocale> <codecvt>(C++11/17/26*) <locale> <regex>(C++11) <text_encoding>(C++26)    Numerics <cfenv>(C++11) <cmath> <complex> <linalg>(C++26) <numbers>(C++20) <random>(C++11) <simd>(C++26) <stdckdint.h>(C++26) <valarray> Time <chrono>(C++11) <ctime> C compatibility <ccomplex>(C++11/17/20*) <ciso646>(until C++20) <cstdalign>(C++11/17/20*) <cstdbool>(C++11/17/20*) <ctgmath>(C++11/17/20*)

Input/output <cinttypes>(C++11) <cstdio> <filesystem>(C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print>(C++23) <spanstream>(C++23) <sstream> <streambuf> <strstream>(C++98/26*) <syncstream>(C++20) Concurrency support <atomic>(C++11) <barrier>(C++20) <condition_variable>(C++11) <future>(C++11) <hazard_pointer>(C++26) <latch>(C++20) <mutex>(C++11) <rcu>(C++26) <semaphore>(C++20) <shared_mutex>(C++14) <stdatomic.h>(C++23) <stop_token>(C++20) <thread>(C++11) Execution support <execution>(C++17)

 

This header is part of the type support library.

Declarations

numeric_limits	provides an interface to query properties of all fundamental numeric types (class template)
float_round_style	indicates floating-point rounding modes (enum)
float_denorm_style	indicates floating-point denormalization modes (enum)

Synopsis

namespace std {enum float_round_style;enum float_denorm_style;   template<class T>class numeric_limits;   template<class T>class numeric_limits<const T>;template<class T>class numeric_limits<volatile T>;template<class T>class numeric_limits<constvolatile T>;   template<>class numeric_limits<bool>;   template<>class numeric_limits<char>;template<>class numeric_limits<signedchar>;template<>class numeric_limits<unsignedchar>;template<>class numeric_limits<char8_t>;template<>class numeric_limits<char16_t>;template<>class numeric_limits<char32_t>;template<>class numeric_limits<wchar_t>;   template<>class numeric_limits<short>;template<>class numeric_limits<int>;template<>class numeric_limits<long>;template<>class numeric_limits<longlong>;template<>class numeric_limits<unsignedshort>;template<>class numeric_limits<unsignedint>;template<>class numeric_limits<unsignedlong>;template<>class numeric_limits<unsignedlonglong>;   template<>class numeric_limits<float>;template<>class numeric_limits<double>;template<>class numeric_limits<longdouble>;}

Enumeration std::float_round_style

namespace std {enum float_round_style { round_indeterminate =-1, round_toward_zero =0, round_to_nearest =1, round_toward_infinity =2, round_toward_neg_infinity =3, };}

Enumeration std::float_denorm_style

namespace std {enum float_denorm_style { denorm_indeterminate =-1, denorm_absent =0, denorm_present =1};}

Class template std::numeric_limits

template<class T>class numeric_limits {public:staticconstexprbool is_specialized =false;   staticconstexpr T min()noexcept{return T();}staticconstexpr T max()noexcept{return T();}staticconstexpr T lowest()noexcept{return T();}   staticconstexprint digits =0;staticconstexprint digits10 =0;staticconstexprint max_digits10 =0;   staticconstexprbool is_signed =false;staticconstexprbool is_integer =false;staticconstexprbool is_exact =false;staticconstexprint radix =0;staticconstexpr T epsilon()noexcept{return T();}staticconstexpr T round_error()noexcept{return T();}   staticconstexprint min_exponent =0;staticconstexprint min_exponent10 =0;staticconstexprint max_exponent =0;staticconstexprint max_exponent10 =0;   staticconstexprbool has_infinity =false;staticconstexprbool has_quiet_NaN =false;staticconstexprbool has_signaling_NaN =false;staticconstexpr float_denorm_style has_denorm = denorm_absent;staticconstexprbool has_denorm_loss =false;staticconstexpr T infinity()noexcept{return T();}staticconstexpr T quiet_NaN()noexcept{return T();}staticconstexpr T signaling_NaN()noexcept{return T();}staticconstexpr T denorm_min()noexcept{return T();}   staticconstexprbool is_iec559 =false;staticconstexprbool is_bounded =false;staticconstexprbool is_modulo =false;   staticconstexprbool traps =false;staticconstexprbool tinyness_before =false;staticconstexpr float_round_style round_style = round_toward_zero;};

Specialization std::numeric_limits<bool>

template<>class numeric_limits<bool>{public:staticconstexprbool is_specialized =true;   staticconstexprbool min()noexcept{returnfalse;}staticconstexprbool max()noexcept{returntrue;}staticconstexprbool lowest()noexcept{returnfalse;}   staticconstexprint digits =1;staticconstexprint digits10 =0;staticconstexprint max_digits10 =0;   staticconstexprbool is_signed =false;staticconstexprbool is_integer =true;staticconstexprbool is_exact =true;staticconstexprint radix =2;staticconstexprbool epsilon()noexcept{return0;}staticconstexprbool round_error()noexcept{return0;}   staticconstexprint min_exponent =0;staticconstexprint min_exponent10 =0;staticconstexprint max_exponent =0;staticconstexprint max_exponent10 =0;   staticconstexprbool has_infinity =false;staticconstexprbool has_quiet_NaN =false;staticconstexprbool has_signaling_NaN =false;staticconstexpr float_denorm_style has_denorm = denorm_absent;staticconstexprbool has_denorm_loss =false;staticconstexprbool infinity()noexcept{return0;}staticconstexprbool quiet_NaN()noexcept{return0;}staticconstexprbool signaling_NaN()noexcept{return0;}staticconstexprbool denorm_min()noexcept{return0;}   staticconstexprbool is_iec559 =false;staticconstexprbool is_bounded =true;staticconstexprbool is_modulo =false;   staticconstexprbool traps =false;staticconstexprbool tinyness_before =false;staticconstexpr float_round_style round_style = round_toward_zero;};

Defect reports

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

DR	Applied to	Behavior as published	Correct behavior
LWG 184	C++98	the definition of the specialization std::numeric_limits<bool> was not provided	provided
LWG 559	C++98	the std::numeric_limits specializations of cv-qualified arithmetic types were missing in the synopsis	added