When you use the TZ environment variable, the Microsoft Visual C++ .NET 2003 C runtime (CRT) localtime and _localtime64 functions incorrectly recognize daylight saving time (DST). These functions recognize DST as starting on the first Sunday of April and ending on the last Sunday of October for all dates. These functions do not recognize DST as starting on the second Sunday of March and ending on the first Sunday of November according to the U.S. Energy Policy Act of 2005.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

To download this hotfix from the MSDN Code Gallery, visit the following Microsoft Web site:

Note The MSDN Code Gallery displays the languages for which the hotfix is available. If you do not see your language listed, it is because the Code Gallery resource page is not available for that language.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:

Prerequisites

You must have Visual Studio .NET 2003 installed before you apply this hotfix.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

For more information, click the following article number to view the article in the Microsoft Knowledge Base: When you use the TZ environment variable, this hotfix changes DST to start on the second Sunday of March and end on the first Sunday of November for dates in 2007 and in later years. For 2006 and for earlier years, DST starts on the first Sunday of April and ends on the last Sunday of October.

Note This hotfix only applies to applications that set the TZ environment variable.

For more information about the TZ environment variable, visit the following Microsoft Developer Network (MSDN) Web site:The following CRT and Microsoft Foundation Classes (MFC) functions call the localtime and _localtime64 functions and may also be affected by this change:

• ctime
• _wctime
• _tctime
• _ctime64
• _wctime64
• _tctime64
• mktime
• _mktime64
• _utime
• _wutime
• _tutime
• _utime64
• _wutime64
• _tutime64
• COleDateTime::operator=
• CTime::GetLocalTm
• CTime::Format