strftime

Defined in header <time.h>

size_t strftime( char *         str, size_t count, 
                 const char *         format, const struct tm *         time );

(until C99)

size_t strftime( char *restrict str, size_t count, 
                 const char *restrict format, const struct tm *restrict time );

(since C99)

Converts the date and time information from a given calendar time time to a null-terminated multibyte character string str according to format string format. Up to count bytes are written.

Parameters

str	-	pointer to the first element of the char array for output
count	-	maximum number of bytes to write
format	-	pointer to a null-terminated multibyte character string specifying the format of conversion. The format string consists of zero or more conversion specifiers and ordinary characters (except %). All ordinary characters, including the terminating null character, are copied to the output string without modification. Each conversion specification begins with % character, optionally followed by E or O modifier (ignored if unsupported by the locale), followed by the character that determines the behavior of the specifier. The following format specifiers are available: Conversion specifier Explanation Used fields % writes literal %. The full conversion specification must be %%. n(C99) writes newline character t(C99) writes horizontal tab character Year Y writes year as a decimal number, e.g. 2017 tm_year EY(C99) writes year in the alternative representation, e.g.平成23年 (year Heisei 23) instead of 2011年 (year 2011) in ja_JP locale tm_year y writes last 2 digits of year as a decimal number (range [00,99]) tm_year Oy(C99) writes last 2 digits of year using the alternative numeric system, e.g. 十一 instead of 11 in ja_JP locale tm_year Ey(C99) writes year as offset from locale's alternative calendar period %EC (locale-dependent) tm_year C(C99) writes first 2 digits of year as a decimal number (range [00,99]) tm_year EC(C99) writes name of the base year (period) in the locale's alternative representation, e.g. 平成 (Heisei era) in ja_JP tm_year G(C99) writes ISO 8601 week-based year, i.e. the year that contains the specified week. In IS0 8601 weeks begin with Monday and the first week of the year must satisfy the following requirements: Includes January 4 Includes first Thursday of the year tm_year, tm_wday, tm_yday g(C99) writes last 2 digits of ISO 8601 week-based year, i.e. the year that contains the specified week (range [00,99]). In IS0 8601 weeks begin with Monday and the first week of the year must satisfy the following requirements: Includes January 4 Includes first Thursday of the year tm_year, tm_wday, tm_yday Month b writes abbreviated month name, e.g. Oct (locale dependent) tm_mon h(C99) synonym of b tm_mon B writes full month name, e.g. October (locale dependent) tm_mon m writes month as a decimal number (range [01,12]) tm_mon Om(C99) writes month using the alternative numeric system, e.g. 十二 instead of 12 in ja_JP locale tm_mon Week U writes week of the year as a decimal number (Sunday is the first day of the week) (range [00,53]) tm_year, tm_wday, tm_yday OU(C99) writes week of the year, as by %U, using the alternative numeric system, e.g. 五十二 instead of 52 in ja_JP locale tm_year, tm_wday, tm_yday W writes week of the year as a decimal number (Monday is the first day of the week) (range [00,53]) tm_year, tm_wday, tm_yday OW(C99) writes week of the year, as by %W, using the alternative numeric system, e.g. 五十二 instead of 52 in ja_JP locale tm_year, tm_wday, tm_yday V(C99) writes ISO 8601 week of the year (range [01,53]). In IS0 8601 weeks begin with Monday and the first week of the year must satisfy the following requirements: Includes January 4 Includes first Thursday of the year tm_year, tm_wday, tm_yday OV(C99) writes week of the year, as by %V, using the alternative numeric system, e.g. 五十二 instead of 52 in ja_JP locale tm_year, tm_wday, tm_yday Day of the year/month j writes day of the year as a decimal number (range [001,366]) tm_yday d writes day of the month as a decimal number (range [01,31]) tm_mday Od(C99) writes zero-based day of the month using the alternative numeric system, e.g 二十七 instead of 27 in ja_JP locale Single character is preceded by a space. tm_mday e(C99) writes day of the month as a decimal number (range [1,31]). Single digit is preceded by a space. tm_mday Oe(C99) writes one-based day of the month using the alternative numeric system, e.g. 二十七 instead of 27 in ja_JP locale Single character is preceded by a space. tm_mday Day of the week a writes abbreviated weekday name, e.g. Fri (locale dependent) tm_wday A writes full weekday name, e.g. Friday (locale dependent) tm_wday w writes weekday as a decimal number, where Sunday is 0 (range [0-6]) tm_wday Ow(C99) writes weekday, where Sunday is 0, using the alternative numeric system, e.g. 二 instead of 2 in ja_JP locale tm_wday u(C99) writes weekday as a decimal number, where Monday is 1 (ISO 8601 format) (range [1-7]) tm_wday Ou(C99) writes weekday, where Monday is 1, using the alternative numeric system, e.g. 二 instead of 2 in ja_JP locale tm_wday Hour, minute, second H writes hour as a decimal number, 24 hour clock (range [00-23]) tm_hour OH(C99) writes hour from 24-hour clock using the alternative numeric system, e.g. 十八 instead of 18 in ja_JP locale tm_hour I writes hour as a decimal number, 12 hour clock (range [01,12]) tm_hour OI(C99) writes hour from 12-hour clock using the alternative numeric system, e.g. 六 instead of 06 in ja_JP locale tm_hour M writes minute as a decimal number (range [00,59]) tm_min OM(C99) writes minute using the alternative numeric system, e.g. 二十五 instead of 25 in ja_JP locale tm_min S writes second as a decimal number (range [00,60]) tm_sec OS(C99) writes second using the alternative numeric system, e.g. 二十四 instead of 24 in ja_JP locale tm_sec Other c writes standard date and time string, e.g. Sun Oct 17 04:41:13 2010 (locale dependent) all Ec(C99) writes alternative date and time string, e.g. using 平成23年 (year Heisei 23) instead of 2011年 (year 2011) in ja_JP locale all x writes localized date representation (locale dependent) all Ex(C99) writes alternative date representation, e.g. using 平成23年 (year Heisei 23) instead of 2011年 (year 2011) in ja_JP locale all X writes localized time representation (locale dependent) all EX(C99) writes alternative time representation (locale dependent) all D(C99) equivalent to "%m/%d/%y" tm_mon, tm_mday, tm_year F(C99) equivalent to "%Y-%m-%d" (the ISO 8601 date format) tm_mon, tm_mday, tm_year r(C99) writes localized 12-hour clock time (locale dependent) tm_hour, tm_min, tm_sec R(C99) equivalent to "%H:%M" tm_hour, tm_min T(C99) equivalent to "%H:%M:%S" (the ISO 8601 time format) tm_hour, tm_min, tm_sec p writes localized a.m. or p.m. (locale dependent) tm_hour z(C99) writes offset from UTC in the ISO 8601 format (e.g. -0430), or no characters if the time zone information is not available tm_isdst Z writes locale-dependent time zone name or abbreviation, or no characters if the time zone information is not available tm_isdst
time	-	pointer to a struct tm object specifying the time to format

Return value

The number of bytes written into the character array pointed to by str not including the terminating '\0' on success. If count was reached before the entire string could be stored, 0 is returned and the contents are undefined.

Example

#include <stdio.h>
#include <time.h>
#include <locale.h>
 
int main(void)
{
    char buff[70];
    struct tm my_time = { .tm_year=112, // = year 2012
                          .tm_mon=9,    // = 10th month
                          .tm_mday=9,   // = 9th day
                          .tm_hour=8,   // = 8 hours
                          .tm_min=10,   // = 10 minutes
                          .tm_sec=20    // = 20 secs
    };
 
    if (strftime(buff, sizeof buff, "%A %c", &my_time)) {
        puts(buff);
    } else {
        puts("strftime failed");
    }
 
    setlocale(LC_TIME, "el_GR.utf8");
 
    if (strftime(buff, sizeof buff, "%A %c", &my_time)) {
        puts(buff);
    } else {
        puts("strftime failed");
    }
}

Output:

Sunday Sun Oct  9 08:10:20 2012
Κυριακή Κυρ 09 Οκτ 2012 08:10:20 πμ EST

References

C11 standard (ISO/IEC 9899:2011):

7.27.3.5 The strftime function (p: 394-397)

C99 standard (ISO/IEC 9899:1999):

7.23.3.5 The strftime function (p: 343-347)

C89/C90 standard (ISO/IEC 9899:1990):

4.12.3.5 The strftime function

asctimeasctime_s (C11)	converts a `tm` object to a textual representation (function)
ctimectime_s (C11)	converts a `time_t` object to a textual representation (function)
wcsftime (C95)	converts a `tm` object to custom wide string textual representation (function)

strftime

Contents

strftime

Parameters

Return value

Example

References

See also