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

 

C++

编译器支持

独立和托管

语言

标准库

标准库头文件

命名需求

功能测试宏 (C++20)

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概念库 (C++20)

元编程库 (C++11)

诊断库

通用工具库

字符串库

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算法库

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输入/输出库

文件系统库 (C++17)

正则表达式库 (C++11)

并发支持库 (C++11)

执行支持库 (C++26)

技术规范

符号索引

外部库

 

工具库

语言支持 类型支持 (基本类型，RTTI) 库功能测试宏 (C++20) 动态内存管理 程序工具 协程支持 (C++20) 可变参数函数 is_constant_evaluated (C++20) is_within_lifetime (C++26) initializer_list (C++11) source_location (C++20) 调试支持 is_debugger_present (C++26) breakpoint_if_debugging (C++26) breakpoint (C++26) 三方比较 three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)    is_eqis_ltis_lteq (C++20)(C++20)(C++20) is_neqis_gtis_gteq (C++20)(C++20)(C++20)

通用工具 日期和时间 函数对象 格式化库 (C++20) bitset hash (C++11) 关系运算符 (在 C++20 中已弃用) rel_ops::operator!=rel_ops::operator>     rel_ops::operator<=rel_ops::operator>= 整数比较函数 cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)    cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) 交换 和 类型操作 swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) 通用词汇类型 pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23) 基本字符串转换 to_chars (C++17) from_chars (C++17) chars_format (C++17) to_chars_result (C++17) from_chars_result (C++17)

 

日期和时间工具

时间点
time_point (C++11)	clock_time_conversion (C++20)	clock_cast (C++20)
持续时间
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)
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)
chrono I/O
parse (C++20)
C 样式日期和时间

 

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<=> (直到 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();		(直到 C++20)
static constexpr duration max() noexcept;		(自 C++20)

返回具有最大可能值的持续时间。

如果持续时间的表示 rep 需要其他实现才能返回最大长度的持续时间，则可以专门化 std::chrono::duration_values 以返回所需的值。

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.

另请参阅

zero [静态]	返回特殊的持续时间值零 (公共静态成员函数)
min [静态]	返回特殊的持续时间值 min (公共静态成员函数)