# timefmt-go
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### Efficient time formatting library (strftime, strptime) for Golang
This is a Go language package for formatting and parsing date time strings.

```go
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`](https://linux.die.net/man/3/strftime) and
[`man 3 strptime`](https://linux.die.net/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 directives like `%W %a` and `%G-W%V-%u`.
- `ParseInLocation` is provided for configuring the default location.

![](https://user-images.githubusercontent.com/375258/88606920-de475c80-d0b8-11ea-8d40-cbfee9e35c2e.jpg)

## Bug Tracker
Report bug at [Issues・itchyny/timefmt-go - GitHub](https://github.com/itchyny/timefmt-go/issues).

## Author
itchyny (<https://github.com/itchyny>)

## License
This software is released under the MIT License, see LICENSE.