Go by Example: Time Formatting / Parsing

Go supports time formatting and parsing via pattern-based layouts.

 
package main

import "fmt"
import "time"

func main() {
    p := fmt.Println

Here’s a basic example of formatting a time according to RFC3339, using the corresponding format constant.

 
    t := time.Now()
    p(t.Format(time.RFC3339))

Time parsing uses the same format values as Format does.

 
    t1, e := time.Parse(
        time.RFC3339,
        "2012-11-01T22:08:41+00:00")
    p(t1)

Format and Parse uses example-based formats. They take a formatted version of the reference time Mon Jan 2 15:04:05 MST 2006 to determine the general pattern with which to format/parse the given time/string. The example time must be exactly as shown: the year 2006, 15 for the hour, Monday for the day of the week, etc. Usually you’ll use a constant from time for these formats, but you can also supply custom formats.

 
    p(t.Format("3:04PM"))
    p(t.Format("Mon Jan _2 15:04:05 2006"))
    p(t.Format("2006-01-02T15:04:05.999999-07:00"))
    form := "3 04 PM"
    t2, e := time.Parse(form, "8 41 PM")
    p(t2)

For purely numeric representations you can also use standard string formatting with the extracted components of the time value.

 
    fmt.Printf("%d-%02d-%02dT%02d:%02d:%02d-00:00\n",
        t.Year(), t.Month(), t.Day(),
        t.Hour(), t.Minute(), t.Second())

Parse will return an error on malformed input explaining the parsing problem.

 
    ansic := "Mon Jan _2 15:04:05 2006"
    _, e = time.Parse(ansic, "8:41PM")
    p(e)
}

$ go run time-formatting-parsing.go 
2014-04-15T18:00:15-07:00
2012-11-01 22:08:41 +0000 +0000
6:00PM
Tue Apr 15 18:00:15 2014
2014-04-15T18:00:15.161182-07:00
0000-01-01 20:41:00 +0000 UTC
2014-04-15T18:00:15-00:00
parsing time "8:41PM" as "Mon Jan _2 15:04:05 2006": \
  cannot parse "8:41PM" as "Mon"

Next example: Random Numbers.

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