Formatted Date and Time Strings

Glossary

• Cultural convention: Data or data formats that are specific to a language, local dialect, or geographic location. Examples are currency symbols, date formats, calendars, numeric separators, and sorting orders.
• Date picture string/time picture string: A string used to represent a date or time format—for example, "MMMM dddd yyyy".
• LCTYPE: A constant defined by Windows that specifies a particular type of locale information.

One of the most useful sets of NLSAPI calls—GetDateFormat, GetTimeFormat, EnumDateFormats, EnumTimeFormats, and EnumCalendarInfo—returns formatted date and time picture strings. EnumDateFormats and EnumTimeFormats, as their names suggest, enumerate the date and time picture strings that the system carries for a particular locale. With these two functions, you can build a list of possible date and time strings to present to the user, such as the one in Figure 5-1 below.

Figure 5-1 The Date and Time dialog box from Microsoft Word 6 for Windows.

GetDateFormat and GetTimeFormat return a single string each. When you use GetDateFormat, your application can request a string containing the correct date in the default short-date format (DATE_SHORTDATE) or the default long-date format (DATE_LONGDATE) for a particular locale, as in the following sample code:

DWORD dwRC = ERROR_SUCCESS
LPTSTR pszDate = (LPTSTR) GlobalAlloc(GPTR, MEMSIZE(nLen + 1));

if ( !pszDate )
return (GetLastError());

int nLen = GetDateFormat(GetThreadLocale(), // Use this thread's
// locale.
DATE_LONGDATE, // Flags are passed
// into this function.
NULL, // Use current system
// time.
pszDateFormat, // format selected by
// user
pszDate, // used for formatted
// date
nLen); // used for date buffer
// length

if ( nLen == 0 )
{
dwRC = GetLastError();
GlobalFree(pszDate);
return (dwRC);
}