Defined in header <ctime> | ||
---|---|---|
char* asctime( const std::tm* time_ptr ); |
Converts given calendar time std::tm
to a textual representation of the following fixed 25-character form: Www Mmm dd hh:mm:ss yyyy\n
.
-
Www
- three-letter English abbreviated day of the week fromtime_ptr->tm_wday
, one ofMon
,Tue
,Wed
,Thu
,Fri
,Sat
,Sun
. -
Mmm
- three-letter English abbreviated month name fromtime_ptr->tm_mon
, one ofJan
,Feb
,Mar
,Apr
,May
,Jun
,Jul
,Aug
,Sep
,Oct
,Nov
,Dec
. -
dd
- 2-digit day of the month fromtimeptr->tm_mday
as if printed bysprintf
using%2d
-
hh
- 2-digit hour fromtimeptr->tm_hour
as if printed bysprintf
using%.2d
-
mm
- 2-digit minute fromtimeptr->tm_min
as if printed bysprintf
using%.2d
-
ss
- 2-digit second fromtimeptr->tm_sec
as if printed bysprintf
using%.2d
-
yyyy
- 4-digit year fromtimeptr->tm_year + 1900
as if printed bysprintf
using%4d
The behavior is undefined if any member of *time_ptr
is outside its normal range.
The behavior is undefined if the calendar year indicated by time_ptr->tm_year
has more than 4 digits or is less than the year 1000.
The function does not support localization, and the newline character cannot be removed.
The function modifies static storage and is not thread-safe.
Parameters
time_ptr | - | pointer to a std::tm object specifying the time to print |
Return value
Pointer to a static null-terminated character string holding the textual representation of date and time. The string may be shared between std::asctime
and std::ctime
, and may be overwritten on each invocation of any of those functions.
Notes
This function returns a pointer to static data and is not thread-safe. POSIX marks this function obsolete and recommends std::strftime
instead.
POSIX limits undefined behaviors only to when the output string would be longer than 25 characters, when timeptr->tm_wday
or timeptr->tm_mon
are not within the expected ranges, or when timeptr->tm_year
exceeds INT_MAX-1990
.
Some implementations handle timeptr->tm_mday==0
as meaning the last day of the preceding month.
Example
#include <ctime> #include <iostream> int main() { std::time_t result = std::time(NULL); std::cout << std::asctime(std::localtime(&result)); }
Output:
Tue Dec 27 16:45:52 2011
See also
converts a time_t object to a textual representation (function) | |
converts a tm object to custom textual representation (function) | |
(C++11) | formats and outputs a date/time value according to the specified format (function template) |
C documentation for asctime |
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