time-formatting-parsing.go

package main

import (
	"fmt"
	"time"
)

// Go supports time formatting and parsing via pattern-based layouts.
func main() {
	p := fmt.Println

	// Here’s a basic example of formatting a time according to RFC3339,
	// using the corresponding layout constant.
	t := time.Now()
	p(t.Format(time.RFC3339))

	// Time parsing uses the same layout values as time.Format.
	t1, e := time.Parse(
		time.RFC3339,
		"2012-11-01T22:08:41+00:00")
	p(t1)

	/*
		Format and Parse use example-based layouts. Usually you’ll use a constant from time
		for these layouts, but you can also supply custom layouts. Layouts must use the
		reference time Mon Jan 2 15:04:05 MST 2006 to show the pattern with which to
		format/parse a 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.
	*/
	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)
}