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When writing ATL components, one of the hardest things to overcome for Windows
programmers, in my opinion, is the dependency on the MFC library. For dates and strings,
MFC simplifies the programmer's job by handling memory allocations and type conversions
within its class encapsulation. However, with that simplification comes the price of
having to distribute the MFC DLL's with your component.
This article focuses on the issues surrounding the use of dates within an ATL
component. I developed the DateLib
component as part of a project for my
company and, as such, the methods of this component are specific to my company's
requirements (I do not have an intellectual property agreement with this company).
However, the DateLib
component does illustrate how to build an ATL component
that has no MFC dependencies, is thread-safe, and will compile as either ANSI or UNICODE.
The methods within the DateLib component are as follows:
Date Formatting Routines:
Now
- Returns the current system date in a DATE
variable.
OLE2Oracle
- For a given DATE
, returns a formatted string
using the DD-Mon-YYYY representation.
Int2Oracle
- For a given month, day, and year, returns a formatted string
using the DD-Mon-YYYY representation.
Int2OLE
- For a given month, day, and year, returns the date in a
DATE
variable.
OLE2String
- For a given DATE
, returns a formatted string
using the MM/DD/YYYY representation.
Date Parsing Routines:
ParseOracle2OLE
- For a given date given in a M/D/YY format, returns the
date in a DATE
variable.
ParseOracle2String
- For a given date given in a M/D/YY format, returns a
formatted string using the MM/DD/YYYY representation.
ParseOracle2Oracle
- For a given date given in a M/D/YY format, returns a
formatted string using the DD-Mon-YYYY representation.
Date Math Routines:
GetFirstDay
- For a given DATE
, returns the first day of the
month in a DATE
variable.
GetLastDay
- For a given DATE
, returns the last day of the
month in a DATE
variable.
GetNextDay
- For a given DATE
, returns the next day's date
in a DATE
variable.
GetNextWeek
- For a given DATE
, returns the next week's date in a
DATE
variable.
GetNextMonth
- For a given DATE
, returns the next month's date in a
DATE
variable.
GetNextYear
- For a given DATE
, returns the next year's date in a
DATE
variable.
GetPreviousDay
- For a given DATE
, returns the previous day's date in
a DATE
variable.
GetPreviousWeek
- For a given DATE
, returns the previous week's date
in a DATE
variable.
GetPreviousMonth
- For a given DATE
, returns the previous month's
date in a DATE
variable.
GetPreviousYear
- For a given DATE, returns the previous year's date
in a DATE
variable.