month() -- Модуль
- std.
date → - Получатель
- Date
- Минимальное число аргументов
- 0
- Максимальное число аргументов
- 0
Declaration and parameters
СсылкаДоступность
Включено по умолчанию · Не определено
Import std.date in language mode 5.21.
The current compiler selects std/date.tpz for this language mode. Availability in other released editions and inclusion in each installed distribution are Pending.
Получатель
Date
Ограничения параметров
Date is an immutable proleptic Gregorian calendar date from 0001-01-01 through 9999-12-31. It contains no time of day, time zone, or locale. The same calendar rules apply before and after 1582.
Date.fromYmd accepts years from 1 through 9999 and months from 1 through 12. The day must be a real day of the selected month and year. All range endpoints are included.
A year divisible by 4 is a leap year except a century year that is not divisible by 400. February has 29 days in a leap year and 28 otherwise. April, June, September, and November have 30 days. The other months have 31.
Valid components return Ok containing that date. Year zero, a year outside the supported range, an invalid month, and an invalid day return Err containing a descriptive nonempty string. Components are not normalized into another date.
The error string describes the failed construction and has no stable machine readable format. Callers branch on Ok or Err.
Date.year, Date.month, and Date.day are calls with no arguments. They return the validated components of the receiver. A valid Date makes these observations total and leaves the receiver unchanged.
Arguments are evaluated once in source order before validation. An earlier fault prevents later evaluation. Constructors and observations do not read a host clock or perform external effects.
Связанное правило · Construct valid Gregorian civil dates →Результат
The declared result type is int.
Эффекты
Ошибки
Result and effects
СсылкаThis call returns the receiver month and leaves the date unchanged.
Resolved contracts
СсылкаRelated entries
СсылкаConstruct valid Gregorian civil dates
СсылкаConstruct valid Gregorian civil dates
Date is an immutable proleptic Gregorian calendar date from 0001-01-01 through 9999-12-31. It contains no time of day, time zone, or locale. The same calendar rules apply before and after 1582.
Date.fromYmd accepts years from 1 through 9999 and months from 1 through 12. The day must be a real day of the selected month and year. All range endpoints are included.
A year divisible by 4 is a leap year except a century year that is not divisible by 400. February has 29 days in a leap year and 28 otherwise. April, June, September, and November have 30 days. The other months have 31.
Valid components return Ok containing that date. Year zero, a year outside the supported range, an invalid month, and an invalid day return Err containing a descriptive nonempty string. Components are not normalized into another date.
The error string describes the failed construction and has no stable machine readable format. Callers branch on Ok or Err.
Date.year, Date.month, and Date.day are calls with no arguments. They return the validated components of the receiver. A valid Date makes these observations total and leaves the receiver unchanged.
Arguments are evaluated once in source order before validation. An earlier fault prevents later evaluation. Constructors and observations do not read a host clock or perform external effects.
Причина
Validating civil dates at construction gives every date observation a definite value. A shared Gregorian calendar and year range make dates independent of locale, time zones, and historical calendar cutovers.
Read leap day and both supported endpoints
Ссылкаimport std.date { Date }import std.testimport std.iolet leap = test.assertOk(Date.fromYmd(2000, 2, 29))io.writeLine("{leap.year()} {leap.month()} {leap.day()}")io.writeLine(leap.toIso())io.writeLine(test.assertOk(Date.fromYmd(1, 1, 1)).toIso())io.writeLine(test.assertOk(Date.fromYmd(9999, 12, 31)).toIso())
2000 2 29
2000-02-29
0001-01-01
9999-12-31
Ожидаемый результат
Ожидаемый результат
Выполнение завершается. Код завершения 0.
2000 2 292000-02-290001-01-019999-12-31
Reject invalid years, months, and days without normalization
Ссылкаimport std.date { Date }import std.iofunction reject(year: int, month: int, day: int) -> () {match (Date.fromYmd(year, month, day)) {case Err(_) => io.writeLine("rejected")case Ok(_) => io.writeLine("accepted")}}reject(1900, 2, 29)reject(2023, 2, 29)reject(2024, 0, 1)reject(2024, 13, 1)reject(2024, 4, 31)reject(2024, 1, 0)reject(2024, 1, 32)reject(-1, 1, 1)reject(10000, 1, 1)reject(9223372036854775807, 1, 1)
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
rejected
Ожидаемый результат
Ожидаемый результат
Выполнение завершается. Код завершения 0.
rejectedrejectedrejectedrejectedrejectedrejectedrejectedrejectedrejectedrejected
Reject year zero during component construction
Ссылкаimport std.date { Date }import std.iomatch (Date.fromYmd(0, 1, 1)) {case Err(_) => io.writeLine("year zero rejected")case Ok(_) => io.writeLine("accepted")}
year zero rejected
Ожидаемый результат
Ожидаемый результат
Выполнение завершается. Код завершения 0.
year zero rejected
Evaluate all components before date validation
Ссылкаimport std.date { Date }import std.iofunction observed(label: string, value: int) -> int {io.writeLine(label)return value}match (Date.fromYmd(observed("year", 2024), observed("month", 13), observed("day", 1))) {case Err(_) => io.writeLine("rejected")case Ok(_) => io.writeLine("accepted")}
year
month
day
rejected
Ожидаемый результат
Ожидаемый результат
Выполнение завершается. Код завершения 0.
yearmonthdayrejected