add- 수신자
- Date
- 최소 인자 수
- 1
- 최대 인자 수
- 1
Declaration and parameters
링크사용 조건
기본 포함 · 미정
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.
수신자
Date
매개변수 제약
Date.addDays accepts a signed int count of whole calendar days. Positive values move forward, negative values move backward, and zero returns the same date value.
The result follows the same proleptic Gregorian calendar as Date.fromYmd. Month boundaries, leap days, and year boundaries are crossed by counting calendar days. Historical calendar cutovers and daylight saving changes do not alter the result.
The result must remain from 0001-01-01 through 9999-12-31. A count whose mathematical result is outside that range raises TPZ4004 during execution. An intermediate integer overflow also raises TPZ4004.
An invalid result does not wrap, saturate, return a partial date, or change the receiver. Evaluation stops at the fault before later statements run.
The receiver is evaluated before the day count and each is evaluated once. An earlier fault prevents later evaluation. The operation has no external effects.
Adding a count and then its negative recovers the starting date when both results lie in range. Date.toIso and the component accessors observe the resulting date without changing it.
관련 규칙 · Add whole calendar days within the civil date range →결과
The declared result type is Date.
효과
실패
Result and effects
링크Calendar arithmetic preserves the receiver. A result outside years 1 through 9999 raises TPZ4004.
Resolved contracts
링크Related entries
링크Add whole calendar days within the civil date range
링크Add whole calendar days within the civil date range
Date.addDays accepts a signed int count of whole calendar days. Positive values move forward, negative values move backward, and zero returns the same date value.
The result follows the same proleptic Gregorian calendar as Date.fromYmd. Month boundaries, leap days, and year boundaries are crossed by counting calendar days. Historical calendar cutovers and daylight saving changes do not alter the result.
The result must remain from 0001-01-01 through 9999-12-31. A count whose mathematical result is outside that range raises TPZ4004 during execution. An intermediate integer overflow also raises TPZ4004.
An invalid result does not wrap, saturate, return a partial date, or change the receiver. Evaluation stops at the fault before later statements run.
The receiver is evaluated before the day count and each is evaluated once. An earlier fault prevents later evaluation. The operation has no external effects.
Adding a count and then its negative recovers the starting date when both results lie in range. Date.toIso and the component accessors observe the resulting date without changing it.
이유
Calendar arithmetic should depend on a date and a day count. A bounded result with an explicit overflow fault prevents wraparound from silently producing a different civil date.
Cross leap days, years, and the full supported interval
링크import std.date { Date }import std.testimport std.iolet leap = test.assertOk(Date.fromYmd(2000, 2, 28))io.writeLine(leap.addDays(1).toIso())io.writeLine(leap.addDays(2).toIso())io.writeLine(leap.toIso())io.writeLine(test.assertOk(Date.fromYmd(1900, 2, 28)).addDays(1).toIso())io.writeLine(test.assertOk(Date.fromYmd(1582, 10, 4)).addDays(1).toIso())io.writeLine(test.assertOk(Date.fromYmd(2000, 1, 1)).addDays(-1).toIso())io.writeLine(leap.addDays(0).toIso())io.writeLine(test.assertOk(Date.fromYmd(1, 1, 1)).addDays(3652058).toIso())io.writeLine(test.assertOk(Date.fromYmd(9999, 12, 31)).addDays(-3652058).toIso())
2000-02-29
2000-03-01
2000-02-28
1900-03-01
1582-10-05
1999-12-31
2000-02-28
9999-12-31
0001-01-01
기대 결과
기대 결과
실행을 마칩니다. 종료 코드 0.
2000-02-292000-03-012000-02-281900-03-011582-10-051999-12-312000-02-289999-12-310001-01-01
Reject the day after the final supported date
링크import std.date { Date }import std.testimport std.iolet date = test.assertOk(Date.fromYmd(9999, 12, 31))date.addDays(1)io.writeLine("after")
표준 출력 없음.기대 결과
Reject the day before the first supported date
링크import std.date { Date }import std.testimport std.iolet date = test.assertOk(Date.fromYmd(1, 1, 1))date.addDays(-1)io.writeLine("after")
표준 출력 없음.기대 결과
Reject a day count that overflows signed arithmetic
링크import std.date { Date }import std.testimport std.iolet date = test.assertOk(Date.fromYmd(1, 1, 1))date.addDays(-9223372036854775808)io.writeLine("after")
표준 출력 없음.기대 결과
Evaluate a date receiver before its day count
링크import std.date { Date }import std.testimport std.iofunction receiver() -> Date {io.writeLine("date")return test.assertOk(Date.fromYmd(2024, 2, 28))}function days() -> int {io.writeLine("days")return 1}let next = receiver().addDays(days())io.writeLine(next.toIso())
date
days
2024-02-29
기대 결과
기대 결과
실행을 마칩니다. 종료 코드 0.
datedays2024-02-29