timefmt-go's Introduction

timefmt-go

Efficient time formatting library (strftime, strptime) for Golang

This is a Go language package for formatting and parsing date time strings.

package main

import (
	"fmt"
	"log"

	"github.com/itchyny/timefmt-go"
)

func main() {
	t, err := timefmt.Parse("2020/07/24 09:07:29", "%Y/%m/%d %H:%M:%S")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(t) // 2020-07-24 09:07:29 +0000 UTC

	str := timefmt.Format(t, "%Y/%m/%d %H:%M:%S")
	fmt.Println(str) // 2020/07/24 09:07:29

	str = timefmt.Format(t, "%a, %d %b %Y %T %z")
	fmt.Println(str) // Fri, 24 Jul 2020 09:07:29 +0000
}

Please refer to man 3 strftime and man 3 strptime for formatters. As an extension, %f directive is supported for zero-padded microseconds, which originates from Python. Note that E and O modifier characters are not supported.

Comparison to other libraries

This library
- provides both formatting and parsing functions in pure Go language,
- depends only on the Go standard libraries not to grow up dependency.
Format (strftime) implements glibc extensions including
- width specifier like %6Y %10B %4Z (limited to 1024 bytes),
- omitting padding modifier like %-y-%-m-%-d,
- space padding modifier like %_y-%_m-%_d,
- upper case modifier like %^a %^b,
- swapping case modifier like %#Z,
- time zone offset modifier like %:z %::z %:::z,
- and its performance is very good.
AppendFormat is provided for reducing allocations.
Parse (strptime) allows to parse
- composed directives like %F %T,
- century years like %C %y,
- week names like %A %a (parsed results are discarded).
ParseInLocation is provided for configuring the default location.