std::asctime

 

C++

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Technical Specifications

 

Utilities library

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Date and time utilities

duration (C++11) time_point (C++11) time_of_day (C++20)	clock_time_conversion (C++20) clock_cast (C++20)
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Calendars
day (C++20) month (C++20) year (C++20) weekday (C++20) operator/ (C++20) year_month_day (C++20) year_month_day_last (C++20) year_month_weekday (C++20) year_month_weekday_last (C++20)	weekday_indexed (C++20) weekday_last (C++20) month_day (C++20) month_day_last (C++20) month_weekday (C++20) month_weekday_last (C++20) year_month (C++20)
Time zones
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C-style date and time

 

C-style date and time utilities

Functions

Time manipulation

difftime

time

clock

timespec_get (C++17)

Format conversions

asctime

ctime

strftime

wcsftime

gmtime

localtime

mktime

Constants

CLOCKS_PER_SEC

Types

tm

time_t

clock_t

timespec (C++17)

 

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 from time_ptr->tm_wday, one of Mon, Tue, Wed, Thu, Fri, Sat, Sun.
• Mmm - three-letter English abbreviated month name from time_ptr->tm_mon, one of Jan, Feb, Mar, Apr, May, Jun, Jul, Aug, Sep, Oct, Nov, Dec.
• dd - 2-digit day of the month from timeptr->tm_mday as if printed by sprintf using %2d
• hh - 2-digit hour from timeptr->tm_hour as if printed by sprintf using %.2d
• mm - 2-digit minute from timeptr->tm_min as if printed by sprintf using %.2d
• ss - 2-digit second from timeptr->tm_sec as if printed by sprintf using %.2d
• yyyy - 4-digit year from timeptr->tm_year + 1900 as if printed by sprintf 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

Run this code

#include <ctime>
#include <iostream>
 
int main()
{
    std::time_t result = std::time(nullptr);
    std::cout << std::asctime(std::localtime(&result));
}

Output:

Mon Apr  3 20:26:26 2017

See also

ctime	converts a time_t object to a textual representation (function)
strftime	converts a tm object to custom textual representation (function)
put_time (C++11)	formats and outputs a date/time value according to the specified format (function template)