std::chrono::duration<Rep,Period>::max

 

C++

编译器支持

独立和宿主

语言

标准库

标准库头文件

具名要求

Feature test macros (C++20)

语言支持库

Concepts library (C++20)

诊断库

内存管理库

Metaprogramming library (C++11)

通用工具库

容器库

迭代器库

Ranges library (C++20)

算法库

字符串库

文本处理库

数值库

日期和时间库

输入/输出库

Filesystem library (C++17)

Concurrency support library (C++11)

Execution control library (C++26)

技术规范

符号索引

外部库

 

日期和时间库

时间点 time_point (C++11) clock_time_conversion (C++20)   clock_cast (C++20) Duration duration (C++11) 时钟 system_clock (C++11) steady_clock (C++11) is_clock (C++20) utc_clock (C++20) tai_clock (C++20) high_resolution_clock (C++11) gps_clock (C++20) file_clock (C++20) local_t (C++20) 一天中的时间 is_amis_pm (C++20)(C++20) make12make24 (C++20)(C++20) hh_mm_ss (C++20)

日历 day (C++20) month (C++20) year (C++20) weekday (C++20) operator/ (C++20) year_month_day (C++20) year_month_day_last (C++20) year_month_weekday (C++20) year_month_weekday_last (C++20)   weekday_indexed (C++20) weekday_last (C++20) month_day (C++20) month_day_last (C++20) month_weekday (C++20) month_weekday_last (C++20) year_month (C++20) last_speclast (C++20)(C++20) chrono I/O parse (C++20)

时区 tzdb (C++20) tzdb_list (C++20) get_tzdbget_tzdb_listreload_tzdbremote_version (C++20)(C++20)(C++20)(C++20) sys_info (C++20) local_info (C++20) nonexistent_local_time (C++20) ambiguous_local_time (C++20) locate_zone (C++20) current_zone (C++20) time_zone (C++20) choose (C++20) zoned_traits (C++20) zoned_time (C++20) time_zone_link (C++20) leap_second (C++20) leap_second_info (C++20) get_leap_second_info (C++20) C 风格的日期和时间

 

std::chrono::duration

成员函数
duration::duration duration::operator= duration::count duration::zero duration::min duration::max duration::operator+duration::operator-	duration::operator++duration::operator-- duration::operator+=duration::operator-=duration::operator*=duration::operator/=duration::operator%=
非成员函数
operator+operator-operator*operator/operator% operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(C++20) operator<< (C++20)	duration_cast floor (C++17) ceil (C++17) round (C++17) abs (C++17) operator""h (C++14) operator""min (C++14) operator""s (C++14) operator""ms (C++14) operator""us (C++14) operator""ns (C++14) from_stream (C++20)
辅助类
common_type treat_as_floating_point      duration_values	formatter<std::chrono::duration> (C++20) hash<std::chrono::duration> (C++26)

 

static constexpr duration max();		(until C++20)
static constexpr duration max() noexcept;		(since C++20)

返回持续时间的最大可能值。

如果 duration 的表示 rep 需要某些其他实现来返回最大长度的 duration，则可以特化 std::chrono::duration_values 以返回期望的值。

参数

(无)

返回值

duration(std::chrono::duration_values<rep>::max())

示例

运行此代码

#include <chrono>
#include <cstdint>
#include <iomanip>
#include <iostream>
 
int main()
{
    constexpr uint64_t chrono_years_max = std::chrono::years::max().count();
    constexpr uint64_t chrono_seconds_max = std::chrono::seconds::max().count();
 
    constexpr uint64_t age_of_universe_in_years{13'787'000'000}; // Λ-CDM ≈ k₁/H₀ = k₂/42
    constexpr uint64_t seconds_per_year{365'25 * 24 * 36}; // 365¼ × 24 × 60 × 60
    constexpr uint64_t age_of_universe_in_seconds{age_of_universe_in_years *
                                                  seconds_per_year};
    std::cout
        << std::scientific << std::setprecision(2)
        << "The Age of the Universe is ≈ "
        << static_cast<double>(age_of_universe_in_years) << " years or "
        << static_cast<double>(age_of_universe_in_seconds) << " seconds.\n\n"
        << "chrono::years::max() = " << chrono_years_max
        << ", sizeof(chrono::years) = "
        << sizeof(std::chrono::years) << " bytes.\n" "chrono::years "
        << (age_of_universe_in_years <= chrono_years_max ? "CAN" : "CANNOT")
        << " keep the Age of the Universe in YEARS.\n\n"
        << "chrono::seconds::max() = " << chrono_seconds_max
        << ", sizeof(chrono::seconds) = "
        << sizeof(std::chrono::seconds) << " bytes.\n" "chrono::seconds "
        << (age_of_universe_in_seconds <= chrono_seconds_max ? "CAN" : "CANNOT")
        << " keep the Age of the Universe in SECONDS.\n";
}

可能的输出

The Age of the Universe is ≈ 1.38e+10 years or 4.35e+17 seconds.
 
chrono::years::max() = 2147483647, sizeof(chrono::years) = 4 bytes.
chrono::years CANNOT keep the Age of the Universe in YEARS.
 
chrono::seconds::max() = 9223372036854775807, sizeof(chrono::seconds) = 8 bytes.
chrono::seconds CAN keep the Age of the Universe in SECONDS.

参见

zero [静态]	返回特殊的 duration 值 zero (public static member function)
min [静态]	返回特殊的 duration 值 min (public static member function)