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The Fc.exe command does not work correctly in Windows XP when the command compares files that differ every 128th byte of a character string

Support for Windows XP has ended

Microsoft ended support for Windows XP on April 8, 2014. This change has affected your software updates and security options. Learn what this means for you and how to stay protected.

On a Windows XP-based computer, you use the Fc.exe command to compare two files. If the two files both contain a character string that has more than 128 bytes, the Fc.exe command may not check the character that appears at every multiple of 128 bytes. Therefore, when you use the Fc.exe command to compare files that differ only at the 128th byte, the 256th byte, the 384th byte, and so on, the Fc.exe command will find no differences. This result is incorrect.

For example, assume that you have two files that both contain a character string of 200 bytes. Also assume that only the character at the 128th byte differs from one file to the other. When you use the Fc.exe command to compare the two files, the command does not display the differences between the two files, and you receive the following output:
Comparing files FileName1 and FileName2
FC: no differences encountered

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.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

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: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


To apply this hotfix, you must have Windows XP Service Pack 2 (SP2) or a later service pack installed. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
322389 How to obtain the latest Windows XP service pack

Restart requirement

You must 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.
Windows XP with Service Pack 2, x86-based versions
File nameFile versionFile sizeDateTimePlatform
Windows XP with Service Pack 3, x86-based versions
File nameFile versionFile sizeDateTimePlatform
To work around this problem, run the Fc.exe command together with the /b (binary) switch.

Note Binary mode does not show the location of the differences between the two files.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Fc.exe is a command that compares two files or two sets of files and then displays the differences between them.

Id. de artículo: 953929 - Última revisión: 10/08/2011 06:49:00 - Revisión: 2.0

Microsoft Windows XP Professional, Microsoft Windows XP Home Edition

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