Package time import "time" Overview Index Examples Subdirectories Overview Package time provides functionality for measuring and displaying time. The calendrical calculations always assume a Gregorian calendar, with no leap seconds. Monotonic Clocks Operating systems provide both a “wall clock,” which is subject to changes for clock synchronization, and a “monotonic clock,” which is not. The general rule is that the wall clock is for telling time and the monotonic clock is for measuring time. Rather than split the API, in this package the Time returned by time.Now contains both a wall clock reading and a monotonic clock reading; later time-telling operations use the wall clock reading, but later time-measuring operations, specifically comparisons and subtractions, use the monotonic clock reading. For example, this code always computes a positive elapsed time of approximately 20 milliseconds, even if the wall clock is changed during the operation being timed: start := time.Now() ... operation that takes 20 milliseconds ... t := time.Now() elapsed := t.Sub(start) Other idioms, such as time.Since(start), time.Until(deadline), and time.Now().Before(deadline), are similarly robust against wall clock resets. The rest of this section gives the precise details of how operations use monotonic clocks, but understanding those details is not required to use this package. The Time returned by time.Now contains a monotonic clock reading. If Time t has a monotonic clock reading, t.Add adds the same duration to both the wall clock and monotonic clock readings to compute the result. Because t.AddDate(y, m, d), t.Round(d), and t.Truncate(d) are wall time computations, they always strip any monotonic clock reading from their results. Because t.In, t.Local, and t.UTC are used for their effect on the interpretation of the wall time, they also strip any monotonic clock reading from their results. The canonical way to strip a monotonic clock reading is to use t = t.Round(0). If Times t and u both contain monotonic clock readings, the operations t.After(u), t.Before(u), t.Equal(u), and t.Sub(u) are carried out using the monotonic clock readings alone, ignoring the wall clock readings. If either t or u contains no monotonic clock reading, these operations fall back to using the wall clock readings. On some systems the monotonic clock will stop if the computer goes to sleep. On such a system, t.Sub(u) may not accurately reflect the actual time that passed between t and u. Because the monotonic clock reading has no meaning outside the current process, the serialized forms generated by t.GobEncode, t.MarshalBinary, t.MarshalJSON, and t.MarshalText omit the monotonic clock reading, and t.Format provides no format for it. Similarly, the constructors time.Date, time.Parse, time.ParseInLocation, and time.Unix, as well as the unmarshalers t.GobDecode, t.UnmarshalBinary. t.UnmarshalJSON, and t.UnmarshalText always create times with no monotonic clock reading. The monotonic clock reading exists only in Time values. It is not a part of Duration values or the Unix times returned by t.Unix and friends. Note that the Go == operator compares not just the time instant but also the Location and the monotonic clock reading. See the documentation for the Time type for a discussion of equality testing for Time values. For debugging, the result of t.String does include the monotonic clock reading if present. If t != u because of different monotonic clock readings, that difference will be visible when printing t.String() and u.String(). Index Constants func After(d Duration) <-chan Time func Sleep(d Duration) func Tick(d Duration) <-chan Time type Duration func ParseDuration(s string) (Duration, error) func Since(t Time) Duration func Until(t Time) Duration func (d Duration) Abs() Duration func (d Duration) Hours() float64 func (d Duration) Microseconds() int64 func (d Duration) Milliseconds() int64 func (d Duration) Minutes() float64 func (d Duration) Nanoseconds() int64 func (d Duration) Round(m Duration) Duration func (d Duration) Seconds() float64 func (d Duration) String() string func (d Duration) Truncate(m Duration) Duration type Location func FixedZone(name string, offset int) *Location func LoadLocation(name string) (*Location, error) func LoadLocationFromTZData(name string, data []byte) (*Location, error) func (l *Location) String() string type Month func (m Month) String() string type ParseError func (e *ParseError) Error() string type Ticker func NewTicker(d Duration) *Ticker func (t *Ticker) Reset(d Duration) func (t *Ticker) Stop() type Time func Date(year int, month Month, day, hour, min, sec, nsec int, loc *Location) Time func Now() Time func Parse(layout, value string) (Time, error) func ParseInLocation(layout, value string, loc *Location) (Time, error) func Unix(sec int64, nsec int64) Time func UnixMicro(usec int64) Time func UnixMilli(msec int64) Time func (t Time) Add(d Duration) Time func (t Time) AddDate(years int, months int, days int) Time func (t Time) After(u Time) bool func (t Time) AppendFormat(b []byte, layout string) []byte func (t Time) Before(u Time) bool func (t Time) Clock() (hour, min, sec int) func (t Time) Date() (year int, month Month, day int) func (t Time) Day() int func (t Time) Equal(u Time) bool func (t Time) Format(layout string) string func (t Time) GoString() string func (t *Time) GobDecode(data []byte) error func (t Time) GobEncode() ([]byte, error) func (t Time) Hour() int func (t Time) ISOWeek() (year, week int) func (t Time) In(loc *Location) Time func (t Time) IsDST() bool func (t Time) IsZero() bool func (t Time) Local() Time func (t Time) Location() *Location func (t Time) MarshalBinary() ([]byte, error) func (t Time) MarshalJSON() ([]byte, error) func (t Time) MarshalText() ([]byte, error) func (t Time) Minute() int func (t Time) Month() Month func (t Time) Nanosecond() int func (t Time) Round(d Duration) Time func (t Time) Second() int func (t Time) String() string func (t Time) Sub(u Time) Duration func (t Time) Truncate(d Duration) Time func (t Time) UTC() Time func (t Time) Unix() int64 func (t Time) UnixMicro() int64 func (t Time) UnixMilli() int64 func (t Time) UnixNano() int64 func (t *Time) UnmarshalBinary(data []byte) error func (t *Time) UnmarshalJSON(data []byte) error func (t *Time) UnmarshalText(data []byte) error func (t Time) Weekday() Weekday func (t Time) Year() int func (t Time) YearDay() int func (t Time) Zone() (name string, offset int) func (t Time) ZoneBounds() (start, end Time) type Timer func AfterFunc(d Duration, f func()) *Timer func NewTimer(d Duration) *Timer func (t *Timer) Reset(d Duration) bool func (t *Timer) Stop() bool type Weekday func (d Weekday) String() string Examples After Date Duration Duration.Hours Duration.Microseconds Duration.Milliseconds Duration.Minutes Duration.Nanoseconds Duration.Round Duration.Seconds Duration.String Duration.Truncate FixedZone LoadLocation Location Month NewTicker Parse ParseDuration ParseInLocation Sleep Tick Time.Add Time.AddDate Time.After Time.AppendFormat Time.Before Time.Date Time.Day Time.Equal Time.Format Time.Format (Pad) Time.GoString Time.Round Time.String Time.Sub Time.Truncate Time.Unix Unix UnixMicro UnixMilli Package files format.go sleep.go sys_unix.go tick.go time.go zoneinfo.go zoneinfo_goroot.go zoneinfo_read.go zoneinfo_unix.go Constants These are predefined layouts for use in Time.Format and time.Parse. The reference time used in these layouts is the specific time stamp: 01/02 03:04:05PM '06 -0700 (January 2, 15:04:05, 2006, in time zone seven hours west of GMT). That value is recorded as the constant named Layout, listed below. As a Unix time, this is 1136239445. Since MST is GMT-0700, the reference would be printed by the Unix date command as: Mon Jan 2 15:04:05 MST 2006 It is a regrettable historic error that the date uses the American convention of putting the numerical month before the day. The example for Time.Format demonstrates the working of the layout string in detail and is a good reference. Note that the RFC822, RFC850, and RFC1123 formats should be applied only to local times. Applying them to UTC times will use "UTC" as the time zone abbreviation, while strictly speaking those RFCs require the use of "GMT" in that case. In general RFC1123Z should be used instead of RFC1123 for servers that insist on that format, and RFC3339 should be preferred for new protocols. RFC3339, RFC822, RFC822Z, RFC1123, and RFC1123Z are useful for formatting; when used with time.Parse they do not accept all the time formats permitted by the RFCs and they do accept time formats not formally defined. The RFC3339Nano format removes trailing zeros from the seconds field and thus may not sort correctly once formatted. Most programs can use one of the defined constants as the layout passed to Format or Parse. The rest of this comment can be ignored unless you are creating a custom layout string. To define your own format, write down what the reference time would look like formatted your way; see the values of constants like ANSIC, StampMicro or Kitchen for examples. The model is to demonstrate what the reference time looks like so that the Format and Parse methods can apply the same transformation to a general time value. Here is a summary of the components of a layout string. Each element shows by example the formatting of an element of the reference time. Only these values are recognized. Text in the layout string that is not recognized as part of the reference time is echoed verbatim during Format and expected to appear verbatim in the input to Parse. Year: "2006" "06" Month: "Jan" "January" "01" "1" Day of the week: "Mon" "Monday" Day of the month: "2" "_2" "02" Day of the year: "__2" "002" Hour: "15" "3" "03" (PM or AM) Minute: "4" "04" Second: "5" "05" AM/PM mark: "PM" Numeric time zone offsets format as follows: "-0700" ±hhmm "-07:00" ±hh:mm "-07" ±hh "-070000" ±hhmmss "-07:00:00" ±hh:mm:ss Replacing the sign in the format with a Z triggers the ISO 8601 behavior of printing Z instead of an offset for the UTC zone. Thus: "Z0700" Z or ±hhmm "Z07:00" Z or ±hh:mm "Z07" Z or ±hh "Z070000" Z or ±hhmmss "Z07:00:00" Z or ±hh:mm:ss Within the format string, the underscores in "_2" and "__2" represent spaces that may be replaced by digits if the following number has multiple digits, for compatibility with fixed-width Unix time formats. A leading zero represents a zero-padded value. The formats __2 and 002 are space-padded and zero-padded three-character day of year; there is no unpadded day of year format. A comma or decimal point followed by one or more zeros represents a fractional second, printed to the given number of decimal places. A comma or decimal point followed by one or more nines represents a fractional second, printed to the given number of decimal places, with trailing zeros removed. For example "15:04:05,000" or "15:04:05.000" formats or parses with millisecond precision. Some valid layouts are invalid time values for time.Parse, due to formats such as _ for space padding and Z for zone information. const ( Layout = "01/02 03:04:05PM '06 -0700" // The reference time, in numerical order. ANSIC = "Mon Jan _2 15:04:05 2006" UnixDate = "Mon Jan _2 15:04:05 MST 2006" RubyDate = "Mon Jan 02 15:04:05 -0700 2006" RFC822 = "02 Jan 06 15:04 MST" RFC822Z = "02 Jan 06 15:04 -0700" // RFC822 with numeric zone RFC850 = "Monday, 02-Jan-06 15:04:05 MST" RFC1123 = "Mon, 02 Jan 2006 15:04:05 MST" RFC1123Z = "Mon, 02 Jan 2006 15:04:05 -0700" // RFC1123 with numeric zone RFC3339 = "2006-01-02T15:04:05Z07:00" RFC3339Nano = "2006-01-02T15:04:05.999999999Z07:00" Kitchen = "3:04PM" // Handy time stamps. Stamp = "Jan _2 15:04:05" StampMilli = "Jan _2 15:04:05.000" StampMicro = "Jan _2 15:04:05.000000" StampNano = "Jan _2 15:04:05.000000000" ) Common durations. There is no definition for units of Day or larger to avoid confusion across daylight savings time zone transitions. To count the number of units in a Duration, divide: second := time.Second fmt.Print(int64(second/time.Millisecond)) // prints 1000 To convert an integer number of units to a Duration, multiply: seconds := 10 fmt.Print(time.Duration(seconds)*time.Second) // prints 10s const ( Nanosecond Duration = 1 Microsecond = 1000 * Nanosecond Millisecond = 1000 * Microsecond Second = 1000 * Millisecond Minute = 60 * Second Hour = 60 * Minute ) func After func After(d Duration) <-chan Time After waits for the duration to elapse and then sends the current time on the returned channel. It is equivalent to NewTimer(d).C. The underlying Timer is not recovered by the garbage collector until the timer fires. If efficiency is a concern, use NewTimer instead and call Timer.Stop if the timer is no longer needed. Example Code: select { case m := <-c: handle(m) case <-time.After(10 * time.Second): fmt.Println("timed out") } func Sleep func Sleep(d Duration) Sleep pauses the current goroutine for at least the duration d. A negative or zero duration causes Sleep to return immediately. Example Code: time.Sleep(100 * time.Millisecond) func Tick func Tick(d Duration) <-chan Time Tick is a convenience wrapper for NewTicker providing access to the ticking channel only. While Tick is useful for clients that have no need to shut down the Ticker, be aware that without a way to shut it down the underlying Ticker cannot be recovered by the garbage collector; it "leaks". Unlike NewTicker, Tick will return nil if d <= 0. Example Code: c := time.Tick(5 * time.Second) for next := range c { fmt.Printf("%v %s\n", next, statusUpdate()) } type Duration A Duration represents the elapsed time between two instants as an int64 nanosecond count. The representation limits the largest representable duration to approximately 290 years. type Duration int64 Example Code: t0 := time.Now() expensiveCall() t1 := time.Now() fmt.Printf("The call took %v to run.\n", t1.Sub(t0)) func ParseDuration func ParseDuration(s string) (Duration, error) ParseDuration parses a duration string. A duration string is a possibly signed sequence of decimal numbers, each with optional fraction and a unit suffix, such as "300ms", "-1.5h" or "2h45m". Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h". Example Code: 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 Since func Since(t Time) Duration Since returns the time elapsed since t. It is shorthand for time.Now().Sub(t). func Until 1.8 func Until(t Time) Duration Until returns the duration until t. It is shorthand for t.Sub(time.Now()). func (Duration) Abs 1.19 func (d Duration) Abs() Duration Abs returns the absolute value of d. As a special case, math.MinInt64 is converted to math.MaxInt64. func (Duration) Hours func (d Duration) Hours() float64 Hours returns the duration as a floating point number of hours. Example Code: 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 (Duration) Microseconds 1.13 func (d Duration) Microseconds() int64 Microseconds returns the duration as an integer microsecond count. Example Code: u, _ := time.ParseDuration("1s") fmt.Printf("One second is %d microseconds.\n", u.Microseconds()) Output: One second is 1000000 microseconds. func (Duration) Milliseconds 1.13 func (d Duration) Milliseconds() int64 Milliseconds returns the duration as an integer millisecond count. Example Code: u, _ := time.ParseDuration("1s") fmt.Printf("One second is %d milliseconds.\n", u.Milliseconds()) Output: One second is 1000 milliseconds. func (Duration) Minutes func (d Duration) Minutes() float64 Minutes returns the duration as a floating point number of minutes. Example Code: m, _ := time.ParseDuration("1h30m") fmt.Printf("The movie is %.0f minutes long.", m.Minutes()) Output: The movie is 90 minutes long. func (Duration) Nanoseconds func (d Duration) Nanoseconds() int64 Nanoseconds returns the duration as an integer nanosecond count. Example Code: u, _ := time.ParseDuration("1µs") fmt.Printf("One microsecond is %d nanoseconds.\n", u.Nanoseconds()) Output: One microsecond is 1000 nanoseconds. func (Duration) Round 1.9 func (d Duration) Round(m Duration) Duration Round returns the result of rounding d to the nearest multiple of m. The rounding behavior for halfway values is to round away from zero. If the result exceeds the maximum (or minimum) value that can be stored in a Duration, Round returns the maximum (or minimum) duration. If m <= 0, Round returns d unchanged. Example Code: 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 (Duration) Seconds func (d Duration) Seconds() float64 Seconds returns the duration as a floating point number of seconds. Example Code: m, _ := time.ParseDuration("1m30s") fmt.Printf("Take off in t-%.0f seconds.", m.Seconds()) Output: Take off in t-90 seconds. func (Duration) String func (d Duration) String() string String returns a string representing the duration in the form "72h3m0.5s". Leading zero units are omitted. As a special case, durations less than one second format use a smaller unit (milli-, micro-, or nanoseconds) to ensure that the leading digit is non-zero. The zero duration formats as 0s. Example Code: fmt.Println(1*time.Hour + 2*time.Minute + 300*time.Millisecond) fmt.Println(300 * time.Millisecond) Output: 1h2m0.3s 300ms func (Duration) Truncate 1.9 func (d Duration) Truncate(m Duration) Duration Truncate returns the result of rounding d toward zero to a multiple of m. If m <= 0, Truncate returns d unchanged. Example Code: 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 type Location A Location maps time instants to the zone in use at that time. Typically, the Location represents the collection of time offsets in use in a geographical area. For many Locations the time offset varies depending on whether daylight savings time is in use at the time instant. type Location struct { // contains filtered or unexported fields } Local represents the system's local time zone. On Unix systems, Local consults the TZ environment variable to find the time zone to use. No TZ means use the system default /etc/localtime. TZ="" means use UTC. TZ="foo" means use file foo in the system timezone directory. var Local *Location = &localLoc UTC represents Universal Coordinated Time (UTC). var UTC *Location = &utcLoc Example Code: // 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 FixedZone func FixedZone(name string, offset int) *Location FixedZone returns a Location that always uses the given zone name and offset (seconds east of UTC). Example Code: 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 func LoadLocation func LoadLocation(name string) (*Location, error) LoadLocation returns the Location with the given name. If the name is "" or "UTC", LoadLocation returns UTC. If the name is "Local", LoadLocation returns Local. Otherwise, the name is taken to be a location name corresponding to a file in the IANA Time Zone database, such as "America/New_York". LoadLocation looks for the IANA Time Zone database in the following locations in order: - the directory or uncompressed zip file named by the ZONEINFO environment variable - on a Unix system, the system standard installation location - $GOROOT/lib/time/zoneinfo.zip - the time/tzdata package, if it was imported Example Code: 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 LoadLocationFromTZData 1.10 func LoadLocationFromTZData(name string, data []byte) (*Location, error) LoadLocationFromTZData returns a Location with the given name initialized from the IANA Time Zone database-formatted data. The data should be in the format of a standard IANA time zone file (for example, the content of /etc/localtime on Unix systems). func (*Location) String func (l *Location) String() string String returns a descriptive name for the time zone information, corresponding to the name argument to LoadLocation or FixedZone. type Month A Month specifies a month of the year (January = 1, ...). type Month int const ( January Month = 1 + iota February March April May June July August September October November December ) Example Code: _, month, day := time.Now().Date() if month == time.November && day == 10 { fmt.Println("Happy Go day!") } func (Month) String func (m Month) String() string String returns the English name of the month ("January", "February", ...). type ParseError ParseError describes a problem parsing a time string. type ParseError struct { Layout string Value string LayoutElem string ValueElem string Message string } func (*ParseError) Error func (e *ParseError) Error() string Error returns the string representation of a ParseError. type Ticker A Ticker holds a channel that delivers “ticks” of a codyhouse@example.org. type Ticker struct { C <-chan Time // The channel on which the ticks are delivered. // contains filtered or unexported fields } func NewTicker func NewTicker(d Duration) *Ticker NewTicker returns a new Ticker containing a channel that will send the current time on the channel after each tick. The period of the ticks is specified by the duration argument. The ticker will adjust the time interval or drop ticks to make up for slow receivers. The duration d must be greater than zero; if not, NewTicker will panic. Stop the ticker to release associated resources. Example Code: 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 (*Ticker) Reset 1.15 func (t *Ticker) Reset(d Duration) Reset stops a ticker and resets its period to the specified duration. The next tick will arrive after the new period elapses. The duration d must be greater than zero; if not, Reset will panic. func (*Ticker) Stop func (t *Ticker) Stop() Stop turns off a ticker. After Stop, no more ticks will be sent. Stop does not close the channel, to prevent a concurrent goroutine reading from the channel from seeing an erroneous "tick". type Time A Time represents an instant in time with nanosecond precision. Programs using times should typically store and pass them as values, not pointers. That is, time variables and struct fields should be of type time.Time, not *time.Time. A Time value can be used by multiple goroutines simultaneously except that the methods GobDecode, UnmarshalBinary, UnmarshalJSON and UnmarshalText are not concurrency-safe. Time instants can be compared using the Before, After, and Equal methods. The Sub method subtracts two instants, producing a Duration. The Add method adds a Time and a Duration, producing a Time. The zero value of type Time is January 1, year 1, 00:00:00.000000000 UTC. As this time is unlikely to come up in practice, the IsZero method gives a simple way of detecting a time that has not been initialized explicitly. Each Time has associated with it a Location, consulted when computing the presentation form of the time, such as in the Format, Hour, and Year methods. The methods Local, UTC, and In return a Time with a specific location. Changing the location in this way changes only the presentation; it does not change the instant in time being denoted and therefore does not affect the computations described in earlier paragraphs. Representations of a Time value saved by the GobEncode, MarshalBinary, MarshalJSON, and MarshalText methods store the Time.Location's offset, but not the location name. They therefore lose information about Daylight Saving Time. In addition to the required “wall clock” reading, a Time may contain an optional reading of the current process's monotonic clock, to provide additional precision for comparison or subtraction. See the “Monotonic Clocks” section in the package documentation for details. Note that the Go == operator compares not just the time instant but also the Location and the monotonic clock reading. Therefore, Time values should not be used as map or database keys without first guaranteeing that the identical Location has been set for all values, which can be achieved through use of the UTC or Local method, and that the monotonic clock reading has been stripped by setting t = t.Round(0). In general, prefer t.Equal(u) to t == u, since t.Equal uses the most accurate comparison available and correctly handles the case when only one of its arguments has a monotonic clock reading. type Time struct { // contains filtered or unexported fields } func Date func Date(year int, month Month, day, hour, min, sec, nsec int, loc *Location) Time Date returns the Time corresponding to yyyy-mm-dd hh:mm:ss + nsec nanoseconds in the appropriate zone for that time in the given location. The month, day, hour, min, sec, and nsec values may be outside their usual ranges and will be normalized during the conversion. For example, October 32 converts to November 1. A daylight savings time transition skips or repeats times. For example, in the United States, March 13, 2011 2:15am never occurred, while November 6, 2011 1:15am occurred twice. In such cases, the choice of time zone, and therefore the time, is not well-defined. Date returns a time that is correct in one of the two zones involved in the transition, but it does not guarantee which. Date panics if loc is nil. Example Code: 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 Now func Now() Time Now returns the current local time. func Parse func Parse(layout, value string) (Time, error) Parse parses a formatted string and returns the time value it represents. See the documentation for the constant called Layout to see how to represent the format. The second argument must be parseable using the format string (layout) provided as the first argument. The example for Time.Format demonstrates the working of the layout string in detail and is a good reference. When parsing (only), the input may contain a fractional second field immediately after the seconds field, even if the layout does not signify its presence. In that case either a comma or a decimal point followed by a maximal series of digits is parsed as a fractional second. Fractional seconds are truncated to nanosecond precision. Elements omitted from the layout are assumed to be zero or, when zero is impossible, one, so parsing "3:04pm" returns the time corresponding to Jan 1, year 0, 15:04:00 UTC (note that because the year is 0, this time is before the zero Time). Years must be in the range 0000..9999. The day of the week is checked for syntax but it is otherwise ignored. For layouts specifying the two-digit year 06, a value NN >= 69 will be treated as 19NN and a value NN < 69 will be treated as 20NN. The remainder of this comment describes the handling of time zones. In the absence of a time zone indicator, Parse returns a time in UTC. When parsing a time with a zone offset like -0700, if the offset corresponds to a time zone used by the current location (Local), then Parse uses that location and zone in the returned time. Otherwise it records the time as being in a fabricated location with time fixed at the given zone offset. When parsing a time with a zone abbreviation like MST, if the zone abbreviation has a defined offset in the current location, then that offset is used. The zone abbreviation "UTC" is recognized as UTC regardless of location. If the zone abbreviation is unknown, Parse records the time as being in a fabricated location with the given zone abbreviation and a zero offset. This choice means that such a time can be parsed and reformatted with the same layout losslessly, but the exact instant used in the representation will differ by the actual zone offset. To avoid such problems, prefer time layouts that use a numeric zone offset, or use ParseInLocation. Example Code: // 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 ParseInLocation 1.1 func ParseInLocation(layout, value string, loc *Location) (Time, error) ParseInLocation is like Parse but differs in two important ways. First, in the absence of time zone information, Parse interprets a time as UTC; ParseInLocation interprets the time as in the given location. Second, when given a zone offset or abbreviation, Parse tries to match it against the Local location; ParseInLocation uses the given location. Example Code: 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 Unix func Unix(sec int64, nsec int64) Time Unix returns the local Time corresponding to the given Unix time, sec seconds and nsec nanoseconds since January 1, 1970 UTC. It is valid to pass nsec outside the range [0, 999999999]. Not all sec values have a corresponding time value. One such value is 1<<63-1 (the largest int64 value). Example Code: unixTime := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC) fmt.Println(unixTime.Unix()) t := time.Unix(unixTime.Unix(), 0).UTC() fmt.Println(t) Output: 1257894000 2009-11-10 23:00:00 +0000 UTC func UnixMicro 1.17 func UnixMicro(usec int64) Time UnixMicro returns the local Time corresponding to the given Unix time, usec microseconds since January 1, 1970 UTC. Example Code: umt := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC) fmt.Println(umt.UnixMicro()) t := time.UnixMicro(umt.UnixMicro()).UTC() fmt.Println(t) Output: 1257894000000000 2009-11-10 23:00:00 +0000 UTC func UnixMilli 1.17 func UnixMilli(msec int64) Time UnixMilli returns the local Time corresponding to the given Unix time, msec milliseconds since January 1, 1970 UTC. Example Code: umt := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC) fmt.Println(umt.UnixMilli()) t := time.UnixMilli(umt.UnixMilli()).UTC() fmt.Println(t) Output: 1257894000000 2009-11-10 23:00:00 +0000 UTC func (Time) Add func (t Time) Add(d Duration) Time Add returns the time t+d. Example Code: 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 (Time) AddDate func (t Time) AddDate(years int, months int, days int) Time AddDate returns the time corresponding to adding the given number of years, months, and days to t. For example, AddDate(-1, 2, 3) applied to January 1, 2011 returns March 4, 2010. AddDate normalizes its result in the same way that Date does, so, for example, adding one month to October 31 yields December 1, the normalized form for November 31. Example Code: 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 (Time) After func (t Time) After(u Time) bool After reports whether the time instant t is after u. Example Code: 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 (Time) AppendFormat 1.5 func (t Time) AppendFormat(b []byte, layout string) []byte AppendFormat is like Format but appends the textual representation to b and returns the extended buffer. Example Code: 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 (Time) Before func (t Time) Before(u Time) bool Before reports whether the time instant t is before u. Example Code: 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 (Time) Clock func (t Time) Clock() (hour, min, sec int) Clock returns the hour, minute, and second within the day specified by t. func (Time) Date func (t Time) Date() (year int, month Month, day int) Date returns the year, month, and day in which t occurs. Example Code: 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 (Time) Day func (t Time) Day() int Day returns the day of the month specified by t. Example Code: 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 (Time) Equal func (t Time) Equal(u Time) bool Equal reports whether t and u represent the same time instant. Two times can be equal even if they are in different locations. For example, 6:00 +0200 and 4:00 UTC are Equal. See the documentation on the Time type for the pitfalls of using == with Time values; most code should use Equal instead. Example Code: 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 (Time) Format func (t Time) Format(layout string) string Format returns a textual representation of the time value formatted according to the layout defined by the argument. See the documentation for the constant called Layout to see how to represent the layout format. The executable example for Time.Format demonstrates the working of the layout string in detail and is a good reference. Example Code: // 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) } tz, err := time.LoadLocation("Asia/Shanghai") 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)) fmt.Println("in Shanghai with seconds:", t.In(tz).Format("2006-01-02T15:04:05 -070000")) fmt.Println("in Shanghai with colon seconds:", t.In(tz).Format("2006-01-02T15:04:05 -07:00:00")) // 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 in Shanghai with seconds: 2015-02-26T03:06:39 +080000 in Shanghai with colon seconds: 2015-02-26T03:06:39 +08:00:00 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" Example (Pad) Code: // 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 (Time) GoString 1.17 func (t Time) GoString() string GoString implements fmt.GoStringer and formats t to be printed in Go source code. Example Code: t := time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC) fmt.Println(t.GoString()) t = t.Add(1 * time.Minute) fmt.Println(t.GoString()) t = t.AddDate(0, 1, 0) fmt.Println(t.GoString()) t, _ = time.Parse("Jan 2, 2006 at 3:04pm (MST)", "Feb 3, 2013 at 7:54pm (UTC)") fmt.Println(t.GoString()) Output: time.Date(2009, time.November, 10, 23, 0, 0, 0, time.UTC) time.Date(2009, time.November, 10, 23, 1, 0, 0, time.UTC) time.Date(2009, time.December, 10, 23, 1, 0, 0, time.UTC) time.Date(2013, time.February, 3, 19, 54, 0, 0, time.UTC) func (*Time) GobDecode func (t *Time) GobDecode(data []byte) error GobDecode implements the gob.GobDecoder interface. func (Time) GobEncode func (t Time) GobEncode() ([]byte, error) GobEncode implements the gob.GobEncoder interface. func (Time) Hour func (t Time) Hour() int Hour returns the hour within the day specified by t, in the range [0, 23]. func (Time) ISOWeek func (t Time) ISOWeek() (year, week int) ISOWeek returns the ISO 8601 year and week number in which t occurs. Week ranges from 1 to 53. Jan 01 to Jan 03 of year n might belong to week 52 or 53 of year n-1, and Dec 29 to Dec 31 might belong to week 1 of year n+1. func (Time) In func (t Time) In(loc *Location) Time In returns a copy of t representing the same time instant, but with the copy's location information set to loc for display purposes. In panics if loc is nil. func (Time) IsDST 1.17 func (t Time) IsDST() bool IsDST reports whether the time in the configured location is in Daylight Savings Time. func (Time) IsZero func (t Time) IsZero() bool IsZero reports whether t represents the zero time instant, January 1, year 1, 00:00:00 UTC. func (Time) Local func (t Time) Local() Time Local returns t with the location set to local time. func (Time) Location func (t Time) Location() *Location Location returns the time zone information associated with t. func (Time) MarshalBinary 1.2 func (t Time) MarshalBinary() ([]byte, error) MarshalBinary implements the encoding.BinaryMarshaler interface. func (Time) MarshalJSON func (t Time) MarshalJSON() ([]byte, error) MarshalJSON implements the json.Marshaler interface. The time is a quoted string in RFC 3339 format, with sub-second precision added if present. func (Time) MarshalText 1.2 func (t Time) MarshalText() ([]byte, error) MarshalText implements the encoding.TextMarshaler interface. The time is formatted in RFC 3339 format, with sub-second precision added if present. func (Time) Minute func (t Time) Minute() int Minute returns the minute offset within the hour specified by t, in the range [0, 59]. func (Time) Month func (t Time) Month() Month Month returns the month of the year specified by t. func (Time) Nanosecond func (t Time) Nanosecond() int Nanosecond returns the nanosecond offset within the second specified by t, in the range [0, 999999999]. func (Time) Round 1.1 func (t Time) Round(d Duration) Time Round returns the result of rounding t to the nearest multiple of d (since the zero time). The rounding behavior for halfway values is to round up. If d <= 0, Round returns t stripped of any monotonic clock reading but otherwise unchanged. Round operates on the time as an absolute duration since the zero time; it does not operate on the presentation form of the time. Thus, Round(Hour) may return a time with a non-zero minute, depending on the time's Location. Example Code: 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 (Time) Second func (t Time) Second() int Second returns the second offset within the minute specified by t, in the range [0, 59]. func (Time) String func (t Time) String() string String returns the time formatted using the format string "2006-01-02 15:04:05.999999999 -0700 MST" If the time has a monotonic clock reading, the returned string includes a final field "m=±<value>", where value is the monotonic clock reading formatted as a decimal number of seconds. The returned string is meant for debugging; for a stable serialized representation, use t.MarshalText, t.MarshalBinary, or t.Format with an explicit format string. Example Code: 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 (Time) Sub func (t Time) Sub(u Time) Duration Sub returns the duration t-u. If the result exceeds the maximum (or minimum) value that can be stored in a Duration, the maximum (or minimum) duration will be returned. To compute t-d for a duration d, use t.Add(-d). Example Code: 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 (Time) Truncate 1.1 func (t Time) Truncate(d Duration) Time Truncate returns the result of rounding t down to a multiple of d (since the zero time). If d <= 0, Truncate returns t stripped of any monotonic clock reading but otherwise unchanged. Truncate operates on the time as an absolute duration since the zero time; it does not operate on the presentation form of the time. Thus, Truncate(Hour) may return a time with a non-zero minute, depending on the time's Location. Example Code: 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 (Time) UTC func (t Time) UTC() Time UTC returns t with the location set to UTC. func (Time) Unix func (t Time) Unix() int64 Unix returns t as a Unix time, the number of seconds elapsed since January 1, 1970 UTC. The result does not depend on the location associated with t. Unix-like operating systems often record time as a 32-bit count of seconds, but since the method here returns a 64-bit value it is valid for billions of years into the past or future. Example Code: // 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 (Time) UnixMicro 1.17 func (t Time) UnixMicro() int64 UnixMicro returns t as a Unix time, the number of microseconds elapsed since January 1, 1970 UTC. The result is undefined if the Unix time in microseconds cannot be represented by an int64 (a date before year -290307 or after year
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