---
name: "fmt_iso8601"
section: "3"
platform: "linux"
package: "libowfat-dev"
version: "0.32-5"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/fmt_iso8601"
---

# fmt\_iso8601(3)

write a date in ASCII conforming to ISO-8601

## NAME

fmt\_iso8601 - write a date in ASCII conforming to ISO-8601

## SYNTAX

**#include \<libowfat/fmt.h\>**

size\_t **fmt\_iso8601**(char \**dest*,time\_t *source*);

## DESCRIPTION

fmt\_iso8601 writes a date in ASCII representation as ISO-8601 defines it: "2014-05-27T19:22:16Z". ISO-8601 also allows to store a sub-second part and a time zone, but fmt\_iso8601 does not support that.

fmt\_iso8601 does not append \\0.

If *dest* equals FMT\_LEN (i.e. is zero), fmt\_iso8601 returns the number of bytes it would have written.

The return value of fmt\_iso8601 is 20 until Jan 1st 10000.