The codes here are those of the standard C language library 'strftime'.
The format argument consists of one or more codes; as in printf, the formatting codes are preceded by a percent sign (%).
Characters that do not begin with % are copied unchanged. The LC_TIME category of the current locale affects the output formatting. (For more information on LC_TIME, see setlocale.) The formatting codes are listed below:
| %a | Abbreviated weekday name |
| %A | Full weekday name |
| %b | Abbreviated month name |
| %B | Full month name |
| %c | Date and time representation appropriate for locale |
| %d | Day of month as decimal number (01 û 31) |
| %H | Hour in 24-hour format (00 û 23) |
| %I | Hour in 12-hour format (01 û 12) |
| %j | Day of year as decimal number (001 û 366) |
| %m | Month as decimal number (01 û 12) |
| %M | Minute as decimal number (00 û 59) |
| %p | Current locale¢s A.M./P.M. indicator for 12-hour clock |
| %S | Second as decimal number (00 û 59) |
| %U | Week of year as decimal number, with Sunday as first day of week (00 û 53) |
| %w | Weekday as decimal number (0 û 6; Sunday is 0) |
| %W | Week of year as decimal number, with Monday as first day of week (00 û 53) |
| %x | Date representation for current locale |
| %X | Time representation for current locale |
| %y | Year without century, as decimal number (00 û 99) |
| %Y | Year with century, as decimal number |
| %z, %Z | Time-zone name or abbreviation; no characters if time zone is unknown |
| %% | Percent sign |
As in the printf function, the # flag may prefix any formatting code. In that case, the meaning of the format code is changed as follows.
Format Code Meaning
%#a, %#A, %#b, %#B, %#p, %#X, %#z, %#Z, %#% # flag is ignored.
%#c Long date and time representation, appropriate for current locale. For example: ôTuesday, March 14, 1995, 12:41:29ö.
%#x Long date representation, appropriate to current locale. For example: ôTuesday, March 14, 1995ö.
%#d, %#H, %#I, %#j, %#m, %#M, %#S, %#U, %#w, %#W, %#y, %#Y Remove leading zeros (if any).