RFC 3339 time parser and formatter

A single C header utility to parse and format RFC 3339 timestamps.

This small library uses struct tm and some function in time.h to store and manipuate the timestamp, so it should be easy to extend and integrate it.

Dependencies

• libc

Installation

This is a single header lib, so just copy rfc3339.h in your project. In the main you have to include it and define RFC3339_IMPL like this:

#define RFC3339_IMPL
#include "rfc3339.h"

int main() {
	...

Examples

Print the current timestamp in rfc3339 format:

#include <stdio.h>
#define RFC3339_IMPL
#include "rfc3339.h"

int main() {
	rfc3339time t = {0};
	char now_str[50] = {0};
	rfc3339time_from_secs(time(0), &t);
	rfc3339time_fmt(now_str, sizeof(now_str), &t);
	printf("Current time: %s\n", now_str);
	return 0;
}

Parse a rfc3339 formatted timestamp:

#include <stdio.h>
#define RFC3339_IMPL
#include "rfc3339.h"

int main() {
	const char* str = "2024-05-01T10:47:40Z";
	rfc3339time t = {0};
	rfc3339time_parse(str, &t);
	printf("Parsed date: %d/%d/%d\n", t.datetime.tm_mday, t.datetime.tm_mon + 1, t.datetime.tm_year + 1900);
	return 0;
}

Parse and convert the timestamp in unix timestamp (with fracsec and timezone support):

#include <stdio.h>
#define RFC3339_IMPL
#include "rfc3339.h"

int main() {
	const char* str = "2024-05-01T10:47:40.123456+01:00";
	rfc3339time t = {0};
	rfc3339time_parse(str, &t);
	printf("Unix timestamp: %ld\n", rfc3339time_as_secs(&t));
	printf("Unix timestamp (microseconds): %ld\n", rfc3339time_as_us(&t));
	return 0;
}