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Q168635: INFO: Explanation of Diff_Ignore

Article: Q168635
Product(s): Microsoft SourceSafe
Version(s): 
Operating System(s): 
Keyword(s): kbSSafe400 kbSSafe500 kbSSafe600
Last Modified: 04-MAY-2001

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The information in this article applies to:

- Microsoft Visual SourceSafe, 16-bit, for Windows, version 4.0 
- Microsoft Visual SourceSafe, 32-bit, for Windows 4.0 
- Microsoft Visual SourceSafe, 16-bit, for Windows, version 4.0a 
- Microsoft Visual SourceSafe, 32-bit, for Windows 4.0a 
- Microsoft Visual SourceSafe for Windows, versions 5.0, 6.0 
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SUMMARY
=======

The Diff_Ignore entry controls the factors that are considered or ignored when
you use the Show Differences (File) command on the Tools menu.

MORE INFORMATION
================

The Visual SourceSafe Show Differences (File) command is used to display all the
relevant changes to a file. The Diff_Ignore variable defines what is a relevant
change. You can control the following four issues in this variable:

  C - case sensitivity
  E - end-of-line characters
  S - small differences* (See explanation of the "S" switch below)
  W - white-space changes

The arguments for the Diff_Ignore variable contain a list of these four letters
with a dash after any variable that you don't want ignored. In the following
example (also the default), E is the only letter that does not have a dash after
it. As a result, end-of-line characters are the only items that will be ignored
when two files are compared.

The following example ignores end-of-line differences, and displays all others:

  Diff_Ignore = c-es-w-

If you change the Diff_Ignore variable, as in the following example, then any
differences in white space would be ignored and any differences in the
end-of-line characters would not be ignored.

The following example ignores white space differences, and displays all others:

  Diff_Ignore = c-e-s-w

* Explanation of the "S" switch: The small differences switch "S" is misnamed.
This option affects small similarities between files, not small differences.

When you run a Show Differences (File) on two files, the diff algorithm tries to
match up everything it can. Therefore, if you have two files with a lot of
differences and a few similarities (both have some blank lines, or lines with
curly braces only, etc.), performing a Show Difference (File) produces a diff
file that shows a number of matching items amidst a larger set of differences.
However, all you really have is a few random matches amidst a larger set of
differences.

Setting the Small Differences switch with a dash after it (Diff_Ignore=c-es- w)
should cause the Show Differences (File) operation to ignore the spurious
similarities between the files.

The Small Differences switch doesn't really affect the output of the Show
Differences (File) when you use the 'Visual' option, but it can make a huge
difference when you are using the 'Unix' option.

REFERENCES
==========

Visual SourceSafe Help: Diff_Ignore

Additional query words:

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Keywords          : kbSSafe400 kbSSafe500 kbSSafe600 
Technology        : kbSSafeSearch kbAudDeveloper kbSSafe600 kbSSafe400 kbSSafe400a kbSSafe500 kbSSafe16bitSearch kbSSafe32bitSearch
Issue type        : kbinfo

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