今後の理解のために、GitHubのAzure/go-autorestのREADME(v14.1.1)を日本語訳しました。
go-autorestは、GoでAzureへアクセスする際の認証や、Goの基本型を変換するヘルパーを利用する際になどに使用します。
package main
import (
"fmt"
"time"
)
func main() {
t := time.Date(2019, 10, 31, 0, 0, 0, 0, time.Local)
fmt.Println(t)
fmt.Println(t.AddDate(0, 1, 0), "(Add 1 month)")
}
package main
import (
"fmt"
"time"
)
// AddMonth returns the time corresponding to adding the
// given number of months to t.
// For example, AddMonth(t, 2) applied to January 1, 2011
// (= t) returns March 1, 2011.
//
// AddMonth does not normalize its result in the same way
// that Date does, so, for example, adding one month to
// October 31 yields November 30.
func AddMonth(t time.Time, months int) time.Time {
lastMonthDay := func(t time.Time) int {
return time.Date(t.Year(), t.Month()+1, 1, 0, 0, 0, 0, t.Location()).AddDate(0, 0, -1).Day()
}
// Creating 1st Date from t and adding months because AddDate() normalizes t.
am := time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, t.Location()).AddDate(0, months, 0)
ad := lastMonthDay(am)
if ld := lastMonthDay(t); t.Day() == ld || t.Day() > ad {
return time.Date(am.Year(), am.Month(), ad, am.Hour(), am.Minute(), am.Second(), am.Nanosecond(), am.Location())
}
return t.AddDate(0, months, 0)
}
func main() {
cnt := 14
fmt.Println("First Days")
ft := time.Date(2020, 2, 1, 0, 0, 0, 0, time.Local)
for i := -cnt; i <= -1; i++ {
fmt.Println(AddMonth(ft, i), "(Add", i, "month)")
}
fmt.Println(ft)
for i := 1; i <= cnt; i++ {
fmt.Println(AddMonth(ft, i), "(Add", i, "month)")
}
fmt.Println()
fmt.Println("Last Days")
lt := time.Date(2020, 2, 29, 0, 0, 0, 0, time.Local)
for i := -cnt; i <= -1; i++ {
fmt.Println(AddMonth(lt, i), "(Add", i, "month)")
}
fmt.Println(lt)
for i := 1; i <= cnt; i++ {
fmt.Println(AddMonth(lt, i), "(Add", i, "month)")
}
}
First Days
2018-12-01 00:00:00 +0000 UTC (Add -14 month)
2019-01-01 00:00:00 +0000 UTC (Add -13 month)
2019-02-01 00:00:00 +0000 UTC (Add -12 month)
2019-03-01 00:00:00 +0000 UTC (Add -11 month)
2019-04-01 00:00:00 +0000 UTC (Add -10 month)
2019-05-01 00:00:00 +0000 UTC (Add -9 month)
2019-06-01 00:00:00 +0000 UTC (Add -8 month)
2019-07-01 00:00:00 +0000 UTC (Add -7 month)
2019-08-01 00:00:00 +0000 UTC (Add -6 month)
2019-09-01 00:00:00 +0000 UTC (Add -5 month)
2019-10-01 00:00:00 +0000 UTC (Add -4 month)
2019-11-01 00:00:00 +0000 UTC (Add -3 month)
2019-12-01 00:00:00 +0000 UTC (Add -2 month)
2020-01-01 00:00:00 +0000 UTC (Add -1 month)
2020-02-01 00:00:00 +0000 UTC
2020-03-01 00:00:00 +0000 UTC (Add 1 month)
2020-04-01 00:00:00 +0000 UTC (Add 2 month)
2020-05-01 00:00:00 +0000 UTC (Add 3 month)
2020-06-01 00:00:00 +0000 UTC (Add 4 month)
2020-07-01 00:00:00 +0000 UTC (Add 5 month)
2020-08-01 00:00:00 +0000 UTC (Add 6 month)
2020-09-01 00:00:00 +0000 UTC (Add 7 month)
2020-10-01 00:00:00 +0000 UTC (Add 8 month)
2020-11-01 00:00:00 +0000 UTC (Add 9 month)
2020-12-01 00:00:00 +0000 UTC (Add 10 month)
2021-01-01 00:00:00 +0000 UTC (Add 11 month)
2021-02-01 00:00:00 +0000 UTC (Add 12 month)
2021-03-01 00:00:00 +0000 UTC (Add 13 month)
2021-04-01 00:00:00 +0000 UTC (Add 14 month)
Last Days
2018-12-31 00:00:00 +0000 UTC (Add -14 month)
2019-01-31 00:00:00 +0000 UTC (Add -13 month)
2019-02-28 00:00:00 +0000 UTC (Add -12 month)
2019-03-31 00:00:00 +0000 UTC (Add -11 month)
2019-04-30 00:00:00 +0000 UTC (Add -10 month)
2019-05-31 00:00:00 +0000 UTC (Add -9 month)
2019-06-30 00:00:00 +0000 UTC (Add -8 month)
2019-07-31 00:00:00 +0000 UTC (Add -7 month)
2019-08-31 00:00:00 +0000 UTC (Add -6 month)
2019-09-30 00:00:00 +0000 UTC (Add -5 month)
2019-10-31 00:00:00 +0000 UTC (Add -4 month)
2019-11-30 00:00:00 +0000 UTC (Add -3 month)
2019-12-31 00:00:00 +0000 UTC (Add -2 month)
2020-01-31 00:00:00 +0000 UTC (Add -1 month)
2020-02-29 00:00:00 +0000 UTC
2020-03-31 00:00:00 +0000 UTC (Add 1 month)
2020-04-30 00:00:00 +0000 UTC (Add 2 month)
2020-05-31 00:00:00 +0000 UTC (Add 3 month)
2020-06-30 00:00:00 +0000 UTC (Add 4 month)
2020-07-31 00:00:00 +0000 UTC (Add 5 month)
2020-08-31 00:00:00 +0000 UTC (Add 6 month)
2020-09-30 00:00:00 +0000 UTC (Add 7 month)
2020-10-31 00:00:00 +0000 UTC (Add 8 month)
2020-11-30 00:00:00 +0000 UTC (Add 9 month)
2020-12-31 00:00:00 +0000 UTC (Add 10 month)
2021-01-31 00:00:00 +0000 UTC (Add 11 month)
2021-02-28 00:00:00 +0000 UTC (Add 12 month)
2021-03-31 00:00:00 +0000 UTC (Add 13 month)
2021-04-30 00:00:00 +0000 UTC (Add 14 month)