ctime_r() — Convert Time to Character String (Restartable)

Format

#include <time.h>
char *ctime_r(const time_t *time, char *buf);

Language Level: XPG4

Threadsafe: Yes.

Locale Sensitive: The behavior of this function might be affected by the LC_TOD category of the current locale. For more information, see Understanding CCSIDs and Locales.

Description

This function is the restartable version of the ctime() function.

The ctime_r() function converts the time value pointed to by time to local time in the form of a character string. A time value is usually obtained by a call to the time() function.

The string result that is produced by the ctime_r() function contains exactly 26 characters and has the format:

   "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n"

For example:

   Mon Jul 16 02:03:55 1987\n\0

The ctime_r() function uses a 24-hour clock format. The days are abbreviated to: Sun, Mon, Tue, Wed, Thu, Fri, and Sat. The months are abbreviated to: Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, and Dec. All fields have a constant width. Dates with only one digit are preceded with a zero. The new-line character (\n) and the null character (\0) occupy the last two positions of the string.

Return Value

The ctime_r() function returns a pointer to the character string result. If the function is unsuccessful, it returns NULL. A call to ctime_r() is equivalent to:

   asctime_r(localtime_r(&anytime, buf2), buf)

where buf is a pointer to char.

Example that uses ctime_r()

This example polls the system clock using ctime_r(). It then prints a message giving the current date and time.

#include <time.h>
#include <stdio.h>
 
int main(void)
{
   time_t ltime;
   char buf[50];
 
   time(&ltime);
	printf("the time is %s", ctime_r(&ltime, buf));
}

Related Information

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