curl_getdate

Section: libcurl Manual (3)
Updated: November 05, 2020
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NAME

curl_getdate - Convert a date string to number of seconds

SYNOPSIS

#include <curl/curl.h>

time_t curl_getdate(char *datestring, time_t *now );

DESCRIPTION

curl_getdate(3) returns the number of seconds since the Epoch, January 1st 1970 00:00:00 in the UTC time zone, for the date and time that the datestring parameter specifies. The now parameter is not used, pass a NULL there.

PARSING DATES AND TIMES

A "date" is a string containing several items separated by whitespace. The order of the items is immaterial. A date string may contain many flavors of items:

calendar date items: Can be specified several ways. Month names can only be three-letter english abbreviations, numbers can be zero-prefixed and the year may use 2 or 4 digits. Examples: 06 Nov 1994, 06-Nov-94 and Nov-94 6.
time of the day items: This string specifies the time on a given day. You must specify it with 6 digits with two colons: HH:MM:SS. To not include the time in a date string, will make the function assume 00:00:00. Example: 18:19:21.
time zone items: Specifies international time zone. There are a few acronyms supported, but in general you should instead use the specific relative time compared to UTC. Supported formats include: -1200, MST, +0100.
day of the week items: Specifies a day of the week. Days of the week may be spelled out in full (using english): `Sunday', `Monday', etc or they may be abbreviated to their first three letters. This is usually not info that adds anything.
pure numbers: If a decimal number of the form YYYYMMDD appears, then YYYY is read as the year, MM as the month number and DD as the day of the month, for the specified calendar date.

EXAMPLES

Sun, 06 Nov 1994 08:49:37 GMT
Sunday, 06-Nov-94 08:49:37 GMT
Sun Nov  6 08:49:37 1994
06 Nov 1994 08:49:37 GMT
06-Nov-94 08:49:37 GMT
Nov  6 08:49:37 1994
06 Nov 1994 08:49:37
06-Nov-94 08:49:37
1994 Nov 6 08:49:37
GMT 08:49:37 06-Nov-94 Sunday
94 6 Nov 08:49:37
1994 Nov 6
06-Nov-94
Sun Nov 6 94
1994.Nov.6
Sun/Nov/6/94/GMT
Sun, 06 Nov 1994 08:49:37 CET
06 Nov 1994 08:49:37 EST
Sun, 12 Sep 2004 15:05:58 -0700
Sat, 11 Sep 2004 21:32:11 +0200
20040912 15:05:58 -0700
20040911 +0200

STANDARDS

This parser was written to handle date formats specified in RFC 822 (including the update in RFC 1123) using time zone name or time zone delta and RFC 850 (obsoleted by RFC 1036) and ANSI C's asctime() format. These formats are the only ones RFC 7231 says HTTP applications may use.

RETURN VALUE

This function returns -1 when it fails to parse the date string. Otherwise it returns the number of seconds as described.

On systems with a signed 32 bit time_t: if the year is larger than 2037 or less than 1903, this function will return -1.

On systems with an unsigned 32 bit time_t: if the year is larger than 2106 or less than 1970, this function will return -1.

On systems with 64 bit time_t: if the year is less than 1583, this function will return -1. (The Gregorian calendar was first introduced 1582 so no "real" dates in this way of doing dates existed before then.)