asctime_r(), asctime64_r() — Convert date and time to a character string

Standards

Format

#define _XOPEN_SOURCE 500
#include <time.h>

char *asctime_r(const struct tm *__restrict__ tm, char *__restrict__ buf);

#define _LARGE_TIME_API
#include <time.h>

char *asctime64_r(const struct tm *__restrict__ tm, char *__restrict__ buf);

General description

The asctime_r() function converts the broken-down time in the structure pointed to by tm into a character string that is placed in the user-supplied buffer pointed to by buf (which contains at least 26 bytes) and then returns buf.

The function asctime64_r() will behave exactly like asctime_r() except it will support a structured date beyond 03:14:07 UTC on January 19, 2038 with a limit of 23:59:59 UTC on December 31, 9999.

Returned value

If successful, asctime_r() returns a pointer to a character string containing the date and time. This string is pointed to by the argument buf.

If unsuccessful, asctime_r() returns NULL.

There are no documented errno values.

Related information

• time.h
• asctime(), asctime64() — Convert time to character string
• ctime(), ctime64() — Convert time to character string
• ctime_r(), ctime64_r() — Convert time value to date and time character string
• gmtime(), gmtime64() — Convert time to broken-down UTC time
• gmtime_r(), gmtime64_r() — Convert a time value to broken-down UTC time
• localdtconv() — Date and time formatting convention inquiry
• localtime(), localtime64() — Convert time and correct for local time
• localtime_r(), localtime64_r() — Convert time value to broken-down local time
• mktime(), mktime64() — Convert local time
• strftime() — Convert to formatted time
• time(),time64() — Determine current UTC time
• tzset() — Set the time zone