diff options
Diffstat (limited to 'src/time/example_test.go')
| -rw-r--r-- | src/time/example_test.go | 664 |
1 files changed, 664 insertions, 0 deletions
diff --git a/src/time/example_test.go b/src/time/example_test.go new file mode 100644 index 0000000..0afb18a --- /dev/null +++ b/src/time/example_test.go @@ -0,0 +1,664 @@ +// Copyright 2011 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package time_test + +import ( + "fmt" + "time" +) + +func expensiveCall() {} + +func ExampleDuration() { + t0 := time.Now() + expensiveCall() + t1 := time.Now() + fmt.Printf("The call took %v to run.\n", t1.Sub(t0)) +} + +func ExampleDuration_Round() { + d, err := time.ParseDuration("1h15m30.918273645s") + if err != nil { + panic(err) + } + + round := []time.Duration{ + time.Nanosecond, + time.Microsecond, + time.Millisecond, + time.Second, + 2 * time.Second, + time.Minute, + 10 * time.Minute, + time.Hour, + } + + for _, r := range round { + fmt.Printf("d.Round(%6s) = %s\n", r, d.Round(r).String()) + } + // Output: + // d.Round( 1ns) = 1h15m30.918273645s + // d.Round( 1µs) = 1h15m30.918274s + // d.Round( 1ms) = 1h15m30.918s + // d.Round( 1s) = 1h15m31s + // d.Round( 2s) = 1h15m30s + // d.Round( 1m0s) = 1h16m0s + // d.Round( 10m0s) = 1h20m0s + // d.Round(1h0m0s) = 1h0m0s +} + +func ExampleDuration_String() { + fmt.Println(1*time.Hour + 2*time.Minute + 300*time.Millisecond) + fmt.Println(300 * time.Millisecond) + // Output: + // 1h2m0.3s + // 300ms +} + +func ExampleDuration_Truncate() { + d, err := time.ParseDuration("1h15m30.918273645s") + if err != nil { + panic(err) + } + + trunc := []time.Duration{ + time.Nanosecond, + time.Microsecond, + time.Millisecond, + time.Second, + 2 * time.Second, + time.Minute, + 10 * time.Minute, + time.Hour, + } + + for _, t := range trunc { + fmt.Printf("d.Truncate(%6s) = %s\n", t, d.Truncate(t).String()) + } + // Output: + // d.Truncate( 1ns) = 1h15m30.918273645s + // d.Truncate( 1µs) = 1h15m30.918273s + // d.Truncate( 1ms) = 1h15m30.918s + // d.Truncate( 1s) = 1h15m30s + // d.Truncate( 2s) = 1h15m30s + // d.Truncate( 1m0s) = 1h15m0s + // d.Truncate( 10m0s) = 1h10m0s + // d.Truncate(1h0m0s) = 1h0m0s +} + +func ExampleParseDuration() { + hours, _ := time.ParseDuration("10h") + complex, _ := time.ParseDuration("1h10m10s") + micro, _ := time.ParseDuration("1µs") + // The package also accepts the incorrect but common prefix u for micro. + micro2, _ := time.ParseDuration("1us") + + fmt.Println(hours) + fmt.Println(complex) + fmt.Printf("There are %.0f seconds in %v.\n", complex.Seconds(), complex) + fmt.Printf("There are %d nanoseconds in %v.\n", micro.Nanoseconds(), micro) + fmt.Printf("There are %6.2e seconds in %v.\n", micro2.Seconds(), micro) + // Output: + // 10h0m0s + // 1h10m10s + // There are 4210 seconds in 1h10m10s. + // There are 1000 nanoseconds in 1µs. + // There are 1.00e-06 seconds in 1µs. +} + +func ExampleDuration_Hours() { + h, _ := time.ParseDuration("4h30m") + fmt.Printf("I've got %.1f hours of work left.", h.Hours()) + // Output: I've got 4.5 hours of work left. +} + +func ExampleDuration_Microseconds() { + u, _ := time.ParseDuration("1s") + fmt.Printf("One second is %d microseconds.\n", u.Microseconds()) + // Output: + // One second is 1000000 microseconds. +} + +func ExampleDuration_Milliseconds() { + u, _ := time.ParseDuration("1s") + fmt.Printf("One second is %d milliseconds.\n", u.Milliseconds()) + // Output: + // One second is 1000 milliseconds. +} + +func ExampleDuration_Minutes() { + m, _ := time.ParseDuration("1h30m") + fmt.Printf("The movie is %.0f minutes long.", m.Minutes()) + // Output: The movie is 90 minutes long. +} + +func ExampleDuration_Nanoseconds() { + u, _ := time.ParseDuration("1µs") + fmt.Printf("One microsecond is %d nanoseconds.\n", u.Nanoseconds()) + // Output: + // One microsecond is 1000 nanoseconds. +} + +func ExampleDuration_Seconds() { + m, _ := time.ParseDuration("1m30s") + fmt.Printf("Take off in t-%.0f seconds.", m.Seconds()) + // Output: Take off in t-90 seconds. +} + +var c chan int + +func handle(int) {} + +func ExampleAfter() { + select { + case m := <-c: + handle(m) + case <-time.After(10 * time.Second): + fmt.Println("timed out") + } +} + +func ExampleSleep() { + time.Sleep(100 * time.Millisecond) +} + +func statusUpdate() string { return "" } + +func ExampleTick() { + c := time.Tick(5 * time.Second) + for next := range c { + fmt.Printf("%v %s\n", next, statusUpdate()) + } +} + +func ExampleMonth() { + _, month, day := time.Now().Date() + if month == time.November && day == 10 { + fmt.Println("Happy Go day!") + } +} + +func ExampleDate() { + t := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC) + fmt.Printf("Go launched at %s\n", t.Local()) + // Output: Go launched at 2009-11-10 15:00:00 -0800 PST +} + +func ExampleNewTicker() { + ticker := time.NewTicker(time.Second) + defer ticker.Stop() + done := make(chan bool) + go func() { + time.Sleep(10 * time.Second) + done <- true + }() + for { + select { + case <-done: + fmt.Println("Done!") + return + case t := <-ticker.C: + fmt.Println("Current time: ", t) + } + } +} + +func ExampleTime_Format() { + // Parse a time value from a string in the standard Unix format. + t, err := time.Parse(time.UnixDate, "Wed Feb 25 11:06:39 PST 2015") + if err != nil { // Always check errors even if they should not happen. + panic(err) + } + + // time.Time's Stringer method is useful without any format. + fmt.Println("default format:", t) + + // Predefined constants in the package implement common layouts. + fmt.Println("Unix format:", t.Format(time.UnixDate)) + + // The time zone attached to the time value affects its output. + fmt.Println("Same, in UTC:", t.UTC().Format(time.UnixDate)) + + // The rest of this function demonstrates the properties of the + // layout string used in the format. + + // The layout string used by the Parse function and Format method + // shows by example how the reference time should be represented. + // We stress that one must show how the reference time is formatted, + // not a time of the user's choosing. Thus each layout string is a + // representation of the time stamp, + // Jan 2 15:04:05 2006 MST + // An easy way to remember this value is that it holds, when presented + // in this order, the values (lined up with the elements above): + // 1 2 3 4 5 6 -7 + // There are some wrinkles illustrated below. + + // Most uses of Format and Parse use constant layout strings such as + // the ones defined in this package, but the interface is flexible, + // as these examples show. + + // Define a helper function to make the examples' output look nice. + do := func(name, layout, want string) { + got := t.Format(layout) + if want != got { + fmt.Printf("error: for %q got %q; expected %q\n", layout, got, want) + return + } + fmt.Printf("%-16s %q gives %q\n", name, layout, got) + } + + // Print a header in our output. + fmt.Printf("\nFormats:\n\n") + + // Simple starter examples. + do("Basic full date", "Mon Jan 2 15:04:05 MST 2006", "Wed Feb 25 11:06:39 PST 2015") + do("Basic short date", "2006/01/02", "2015/02/25") + + // The hour of the reference time is 15, or 3PM. The layout can express + // it either way, and since our value is the morning we should see it as + // an AM time. We show both in one format string. Lower case too. + do("AM/PM", "3PM==3pm==15h", "11AM==11am==11h") + + // When parsing, if the seconds value is followed by a decimal point + // and some digits, that is taken as a fraction of a second even if + // the layout string does not represent the fractional second. + // Here we add a fractional second to our time value used above. + t, err = time.Parse(time.UnixDate, "Wed Feb 25 11:06:39.1234 PST 2015") + if err != nil { + panic(err) + } + // It does not appear in the output if the layout string does not contain + // a representation of the fractional second. + do("No fraction", time.UnixDate, "Wed Feb 25 11:06:39 PST 2015") + + // Fractional seconds can be printed by adding a run of 0s or 9s after + // a decimal point in the seconds value in the layout string. + // If the layout digits are 0s, the fractional second is of the specified + // width. Note that the output has a trailing zero. + do("0s for fraction", "15:04:05.00000", "11:06:39.12340") + + // If the fraction in the layout is 9s, trailing zeros are dropped. + do("9s for fraction", "15:04:05.99999999", "11:06:39.1234") + + // Output: + // default format: 2015-02-25 11:06:39 -0800 PST + // Unix format: Wed Feb 25 11:06:39 PST 2015 + // Same, in UTC: Wed Feb 25 19:06:39 UTC 2015 + // + // Formats: + // + // Basic full date "Mon Jan 2 15:04:05 MST 2006" gives "Wed Feb 25 11:06:39 PST 2015" + // Basic short date "2006/01/02" gives "2015/02/25" + // AM/PM "3PM==3pm==15h" gives "11AM==11am==11h" + // No fraction "Mon Jan _2 15:04:05 MST 2006" gives "Wed Feb 25 11:06:39 PST 2015" + // 0s for fraction "15:04:05.00000" gives "11:06:39.12340" + // 9s for fraction "15:04:05.99999999" gives "11:06:39.1234" + +} + +func ExampleTime_Format_pad() { + // Parse a time value from a string in the standard Unix format. + t, err := time.Parse(time.UnixDate, "Sat Mar 7 11:06:39 PST 2015") + if err != nil { // Always check errors even if they should not happen. + panic(err) + } + + // Define a helper function to make the examples' output look nice. + do := func(name, layout, want string) { + got := t.Format(layout) + if want != got { + fmt.Printf("error: for %q got %q; expected %q\n", layout, got, want) + return + } + fmt.Printf("%-16s %q gives %q\n", name, layout, got) + } + + // The predefined constant Unix uses an underscore to pad the day. + do("Unix", time.UnixDate, "Sat Mar 7 11:06:39 PST 2015") + + // For fixed-width printing of values, such as the date, that may be one or + // two characters (7 vs. 07), use an _ instead of a space in the layout string. + // Here we print just the day, which is 2 in our layout string and 7 in our + // value. + do("No pad", "<2>", "<7>") + + // An underscore represents a space pad, if the date only has one digit. + do("Spaces", "<_2>", "< 7>") + + // A "0" indicates zero padding for single-digit values. + do("Zeros", "<02>", "<07>") + + // If the value is already the right width, padding is not used. + // For instance, the second (05 in the reference time) in our value is 39, + // so it doesn't need padding, but the minutes (04, 06) does. + do("Suppressed pad", "04:05", "06:39") + + // Output: + // Unix "Mon Jan _2 15:04:05 MST 2006" gives "Sat Mar 7 11:06:39 PST 2015" + // No pad "<2>" gives "<7>" + // Spaces "<_2>" gives "< 7>" + // Zeros "<02>" gives "<07>" + // Suppressed pad "04:05" gives "06:39" + +} + +func ExampleParse() { + // See the example for Time.Format for a thorough description of how + // to define the layout string to parse a time.Time value; Parse and + // Format use the same model to describe their input and output. + + // longForm shows by example how the reference time would be represented in + // the desired layout. + const longForm = "Jan 2, 2006 at 3:04pm (MST)" + t, _ := time.Parse(longForm, "Feb 3, 2013 at 7:54pm (PST)") + fmt.Println(t) + + // shortForm is another way the reference time would be represented + // in the desired layout; it has no time zone present. + // Note: without explicit zone, returns time in UTC. + const shortForm = "2006-Jan-02" + t, _ = time.Parse(shortForm, "2013-Feb-03") + fmt.Println(t) + + // Some valid layouts are invalid time values, due to format specifiers + // such as _ for space padding and Z for zone information. + // For example the RFC3339 layout 2006-01-02T15:04:05Z07:00 + // contains both Z and a time zone offset in order to handle both valid options: + // 2006-01-02T15:04:05Z + // 2006-01-02T15:04:05+07:00 + t, _ = time.Parse(time.RFC3339, "2006-01-02T15:04:05Z") + fmt.Println(t) + t, _ = time.Parse(time.RFC3339, "2006-01-02T15:04:05+07:00") + fmt.Println(t) + _, err := time.Parse(time.RFC3339, time.RFC3339) + fmt.Println("error", err) // Returns an error as the layout is not a valid time value + + // Output: + // 2013-02-03 19:54:00 -0800 PST + // 2013-02-03 00:00:00 +0000 UTC + // 2006-01-02 15:04:05 +0000 UTC + // 2006-01-02 15:04:05 +0700 +0700 + // error parsing time "2006-01-02T15:04:05Z07:00": extra text: "07:00" +} + +func ExampleParseInLocation() { + loc, _ := time.LoadLocation("Europe/Berlin") + + // This will look for the name CEST in the Europe/Berlin time zone. + const longForm = "Jan 2, 2006 at 3:04pm (MST)" + t, _ := time.ParseInLocation(longForm, "Jul 9, 2012 at 5:02am (CEST)", loc) + fmt.Println(t) + + // Note: without explicit zone, returns time in given location. + const shortForm = "2006-Jan-02" + t, _ = time.ParseInLocation(shortForm, "2012-Jul-09", loc) + fmt.Println(t) + + // Output: + // 2012-07-09 05:02:00 +0200 CEST + // 2012-07-09 00:00:00 +0200 CEST +} + +func ExampleTime_Unix() { + // 1 billion seconds of Unix, three ways. + fmt.Println(time.Unix(1e9, 0).UTC()) // 1e9 seconds + fmt.Println(time.Unix(0, 1e18).UTC()) // 1e18 nanoseconds + fmt.Println(time.Unix(2e9, -1e18).UTC()) // 2e9 seconds - 1e18 nanoseconds + + t := time.Date(2001, time.September, 9, 1, 46, 40, 0, time.UTC) + fmt.Println(t.Unix()) // seconds since 1970 + fmt.Println(t.UnixNano()) // nanoseconds since 1970 + + // Output: + // 2001-09-09 01:46:40 +0000 UTC + // 2001-09-09 01:46:40 +0000 UTC + // 2001-09-09 01:46:40 +0000 UTC + // 1000000000 + // 1000000000000000000 +} + +func ExampleTime_Round() { + t := time.Date(0, 0, 0, 12, 15, 30, 918273645, time.UTC) + round := []time.Duration{ + time.Nanosecond, + time.Microsecond, + time.Millisecond, + time.Second, + 2 * time.Second, + time.Minute, + 10 * time.Minute, + time.Hour, + } + + for _, d := range round { + fmt.Printf("t.Round(%6s) = %s\n", d, t.Round(d).Format("15:04:05.999999999")) + } + // Output: + // t.Round( 1ns) = 12:15:30.918273645 + // t.Round( 1µs) = 12:15:30.918274 + // t.Round( 1ms) = 12:15:30.918 + // t.Round( 1s) = 12:15:31 + // t.Round( 2s) = 12:15:30 + // t.Round( 1m0s) = 12:16:00 + // t.Round( 10m0s) = 12:20:00 + // t.Round(1h0m0s) = 12:00:00 +} + +func ExampleTime_Truncate() { + t, _ := time.Parse("2006 Jan 02 15:04:05", "2012 Dec 07 12:15:30.918273645") + trunc := []time.Duration{ + time.Nanosecond, + time.Microsecond, + time.Millisecond, + time.Second, + 2 * time.Second, + time.Minute, + 10 * time.Minute, + } + + for _, d := range trunc { + fmt.Printf("t.Truncate(%5s) = %s\n", d, t.Truncate(d).Format("15:04:05.999999999")) + } + // To round to the last midnight in the local timezone, create a new Date. + midnight := time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, time.Local) + _ = midnight + + // Output: + // t.Truncate( 1ns) = 12:15:30.918273645 + // t.Truncate( 1µs) = 12:15:30.918273 + // t.Truncate( 1ms) = 12:15:30.918 + // t.Truncate( 1s) = 12:15:30 + // t.Truncate( 2s) = 12:15:30 + // t.Truncate( 1m0s) = 12:15:00 + // t.Truncate(10m0s) = 12:10:00 +} + +func ExampleLoadLocation() { + location, err := time.LoadLocation("America/Los_Angeles") + if err != nil { + panic(err) + } + + timeInUTC := time.Date(2018, 8, 30, 12, 0, 0, 0, time.UTC) + fmt.Println(timeInUTC.In(location)) + // Output: 2018-08-30 05:00:00 -0700 PDT +} + +func ExampleLocation() { + // China doesn't have daylight saving. It uses a fixed 8 hour offset from UTC. + secondsEastOfUTC := int((8 * time.Hour).Seconds()) + beijing := time.FixedZone("Beijing Time", secondsEastOfUTC) + + // If the system has a timezone database present, it's possible to load a location + // from that, e.g.: + // newYork, err := time.LoadLocation("America/New_York") + + // Creating a time requires a location. Common locations are time.Local and time.UTC. + timeInUTC := time.Date(2009, 1, 1, 12, 0, 0, 0, time.UTC) + sameTimeInBeijing := time.Date(2009, 1, 1, 20, 0, 0, 0, beijing) + + // Although the UTC clock time is 1200 and the Beijing clock time is 2000, Beijing is + // 8 hours ahead so the two dates actually represent the same instant. + timesAreEqual := timeInUTC.Equal(sameTimeInBeijing) + fmt.Println(timesAreEqual) + + // Output: + // true +} + +func ExampleTime_Add() { + start := time.Date(2009, 1, 1, 12, 0, 0, 0, time.UTC) + afterTenSeconds := start.Add(time.Second * 10) + afterTenMinutes := start.Add(time.Minute * 10) + afterTenHours := start.Add(time.Hour * 10) + afterTenDays := start.Add(time.Hour * 24 * 10) + + fmt.Printf("start = %v\n", start) + fmt.Printf("start.Add(time.Second * 10) = %v\n", afterTenSeconds) + fmt.Printf("start.Add(time.Minute * 10) = %v\n", afterTenMinutes) + fmt.Printf("start.Add(time.Hour * 10) = %v\n", afterTenHours) + fmt.Printf("start.Add(time.Hour * 24 * 10) = %v\n", afterTenDays) + + // Output: + // start = 2009-01-01 12:00:00 +0000 UTC + // start.Add(time.Second * 10) = 2009-01-01 12:00:10 +0000 UTC + // start.Add(time.Minute * 10) = 2009-01-01 12:10:00 +0000 UTC + // start.Add(time.Hour * 10) = 2009-01-01 22:00:00 +0000 UTC + // start.Add(time.Hour * 24 * 10) = 2009-01-11 12:00:00 +0000 UTC +} + +func ExampleTime_AddDate() { + start := time.Date(2009, 1, 1, 0, 0, 0, 0, time.UTC) + oneDayLater := start.AddDate(0, 0, 1) + oneMonthLater := start.AddDate(0, 1, 0) + oneYearLater := start.AddDate(1, 0, 0) + + fmt.Printf("oneDayLater: start.AddDate(0, 0, 1) = %v\n", oneDayLater) + fmt.Printf("oneMonthLater: start.AddDate(0, 1, 0) = %v\n", oneMonthLater) + fmt.Printf("oneYearLater: start.AddDate(1, 0, 0) = %v\n", oneYearLater) + + // Output: + // oneDayLater: start.AddDate(0, 0, 1) = 2009-01-02 00:00:00 +0000 UTC + // oneMonthLater: start.AddDate(0, 1, 0) = 2009-02-01 00:00:00 +0000 UTC + // oneYearLater: start.AddDate(1, 0, 0) = 2010-01-01 00:00:00 +0000 UTC +} + +func ExampleTime_After() { + year2000 := time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC) + year3000 := time.Date(3000, 1, 1, 0, 0, 0, 0, time.UTC) + + isYear3000AfterYear2000 := year3000.After(year2000) // True + isYear2000AfterYear3000 := year2000.After(year3000) // False + + fmt.Printf("year3000.After(year2000) = %v\n", isYear3000AfterYear2000) + fmt.Printf("year2000.After(year3000) = %v\n", isYear2000AfterYear3000) + + // Output: + // year3000.After(year2000) = true + // year2000.After(year3000) = false +} + +func ExampleTime_Before() { + year2000 := time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC) + year3000 := time.Date(3000, 1, 1, 0, 0, 0, 0, time.UTC) + + isYear2000BeforeYear3000 := year2000.Before(year3000) // True + isYear3000BeforeYear2000 := year3000.Before(year2000) // False + + fmt.Printf("year2000.Before(year3000) = %v\n", isYear2000BeforeYear3000) + fmt.Printf("year3000.Before(year2000) = %v\n", isYear3000BeforeYear2000) + + // Output: + // year2000.Before(year3000) = true + // year3000.Before(year2000) = false +} + +func ExampleTime_Date() { + d := time.Date(2000, 2, 1, 12, 30, 0, 0, time.UTC) + year, month, day := d.Date() + + fmt.Printf("year = %v\n", year) + fmt.Printf("month = %v\n", month) + fmt.Printf("day = %v\n", day) + + // Output: + // year = 2000 + // month = February + // day = 1 +} + +func ExampleTime_Day() { + d := time.Date(2000, 2, 1, 12, 30, 0, 0, time.UTC) + day := d.Day() + + fmt.Printf("day = %v\n", day) + + // Output: + // day = 1 +} + +func ExampleTime_Equal() { + secondsEastOfUTC := int((8 * time.Hour).Seconds()) + beijing := time.FixedZone("Beijing Time", secondsEastOfUTC) + + // Unlike the equal operator, Equal is aware that d1 and d2 are the + // same instant but in different time zones. + d1 := time.Date(2000, 2, 1, 12, 30, 0, 0, time.UTC) + d2 := time.Date(2000, 2, 1, 20, 30, 0, 0, beijing) + + datesEqualUsingEqualOperator := d1 == d2 + datesEqualUsingFunction := d1.Equal(d2) + + fmt.Printf("datesEqualUsingEqualOperator = %v\n", datesEqualUsingEqualOperator) + fmt.Printf("datesEqualUsingFunction = %v\n", datesEqualUsingFunction) + + // Output: + // datesEqualUsingEqualOperator = false + // datesEqualUsingFunction = true +} + +func ExampleTime_String() { + timeWithNanoseconds := time.Date(2000, 2, 1, 12, 13, 14, 15, time.UTC) + withNanoseconds := timeWithNanoseconds.String() + + timeWithoutNanoseconds := time.Date(2000, 2, 1, 12, 13, 14, 0, time.UTC) + withoutNanoseconds := timeWithoutNanoseconds.String() + + fmt.Printf("withNanoseconds = %v\n", string(withNanoseconds)) + fmt.Printf("withoutNanoseconds = %v\n", string(withoutNanoseconds)) + + // Output: + // withNanoseconds = 2000-02-01 12:13:14.000000015 +0000 UTC + // withoutNanoseconds = 2000-02-01 12:13:14 +0000 UTC +} + +func ExampleTime_Sub() { + start := time.Date(2000, 1, 1, 0, 0, 0, 0, time.UTC) + end := time.Date(2000, 1, 1, 12, 0, 0, 0, time.UTC) + + difference := end.Sub(start) + fmt.Printf("difference = %v\n", difference) + + // Output: + // difference = 12h0m0s +} + +func ExampleTime_AppendFormat() { + t := time.Date(2017, time.November, 4, 11, 0, 0, 0, time.UTC) + text := []byte("Time: ") + + text = t.AppendFormat(text, time.Kitchen) + fmt.Println(string(text)) + + // Output: + // Time: 11:00AM +} + +func ExampleFixedZone() { + loc := time.FixedZone("UTC-8", -8*60*60) + t := time.Date(2009, time.November, 10, 23, 0, 0, 0, loc) + fmt.Println("The time is:", t.Format(time.RFC822)) + // Output: The time is: 10 Nov 09 23:00 UTC-8 +} |