// 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 }