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Run Format

Source file src/time/example_test.go

Documentation: time

  // 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() {
  	t1 := time.Date(2016, time.August, 15, 0, 0, 0, 0, time.UTC)
  	t2 := time.Date(2017, time.February, 16, 0, 0, 0, 0, time.UTC)
  	fmt.Println(t2.Sub(t1).String())
  	// Output: 4440h0m0s
  }
  
  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("t.Truncate(%6s) = %s\n", t, d.Truncate(t).String())
  	}
  	// Output:
  	// t.Truncate(   1ns) = 1h15m30.918273645s
  	// t.Truncate(   1µs) = 1h15m30.918273s
  	// t.Truncate(   1ms) = 1h15m30.918s
  	// t.Truncate(    1s) = 1h15m30s
  	// t.Truncate(    2s) = 1h15m30s
  	// t.Truncate(  1m0s) = 1h15m0s
  	// t.Truncate( 10m0s) = 1h10m0s
  	// t.Truncate(1h0m0s) = 1h0m0s
  }
  
  func ExampleParseDuration() {
  	hours, _ := time.ParseDuration("10h")
  	complex, _ := time.ParseDuration("1h10m10s")
  
  	fmt.Println(hours)
  	fmt.Println(complex)
  	fmt.Printf("there are %.0f seconds in %v\n", complex.Seconds(), complex)
  	// Output:
  	// 10h0m0s
  	// 1h10m10s
  	// there are 4210 seconds in 1h10m10s
  }
  
  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_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() {
  	ns, _ := time.ParseDuration("1000ns")
  	fmt.Printf("one microsecond has %d nanoseconds.", ns.Nanoseconds())
  	// Output: one microsecond has 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(5 * time.Minute):
  		fmt.Println("timed out")
  	}
  }
  
  func ExampleSleep() {
  	time.Sleep(100 * time.Millisecond)
  }
  
  func statusUpdate() string { return "" }
  
  func ExampleTick() {
  	c := time.Tick(1 * time.Minute)
  	for now := range c {
  		fmt.Printf("%v %s\n", now, 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, "Sat Mar  7 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("%-15s %q gives %q\n", name, layout, got)
  	}
  
  	// Print a header in our output.
  	fmt.Printf("\nFormats:\n\n")
  
  	// A simple starter example.
  	do("Basic", "Mon Jan 2 15:04:05 MST 2006", "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")
  
  	// The predefined constant Unix uses an underscore to pad the day.
  	// Compare with our simple starter example.
  	do("Unix", time.UnixDate, "Sat Mar  7 11:06:39 PST 2015")
  
  	// 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, "Sat Mar  7 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, "Sat Mar  7 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: 2015-03-07 11:06:39 -0800 PST
  	// Unix format: Sat Mar  7 11:06:39 PST 2015
  	// Same, in UTC: Sat Mar  7 19:06:39 UTC 2015
  	//
  	// Formats:
  	//
  	// Basic           "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"
  	// Unix            "Mon Jan _2 15:04:05 MST 2006" gives "Sat Mar  7 11:06:39 PST 2015"
  	// AM/PM           "3PM==3pm==15h" gives "11AM==11am==11h"
  	// No fraction     "Mon Jan _2 15:04:05 MST 2006" gives "Sat Mar  7 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 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")
  
  	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 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
  }
  

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