Chapter 5. Questions and Answers

Tools named KDiff and KDiff2 (now called Kompare) already exist. Also KDiff3 should suggest that it can merge like the diff3 tool in the Diff-Tool collection.

I'm using GPL programs for a very long time now and learned very much by having a look at many of the sources. Hence this is my "Thank You" to all programmers that also did so or will do the same.

You compiled from source but you probably didn't specify the correct prefix for the installation. By default cmake wants to install in /usr/local but then the user-interface resource file (i.e. kdiff3ui.rc) can't be found. The README file contains more information about the correct prefix.

Lines where only the amount of white space characters is different are treated as "equal" at first, while just one different non-white character causes the lines to be "different". If similar lines appear next to each other, this actually is coincidence but this fortunately is often the case. See also Manual Diff Help.

For each equal or different section the editor in the merge result window remembers where it begins or ends. This is needed so that conflicts can be solved manually by simply selecting the source button (A, B or C). This information is lost while saving as text and it is too much effort to create a special file format that supports saving and restoring all necessary information.

Click into the summary column left of the text. (See also here.)

This is a side effect of git's internal workings. If you try to compare a previous revision to the current work tree git will compare actually files representing the past commit to symlinks pointing to the worktree. As of 1.9 KDiff3 defaults to having Follow file links and Follow folder links on. Prior to this they were off by default. This did not matter when not doing if "Full analysis" was also off. However, with Full analysis on KDiff3 would initially attempt to compare the path pointed to by a link rather than follow it. Prior to 1.8 the resulting error was ignored. However, 1.8 began reporting the error.

This was too much effort until now. You can always restore a version from one source (A, B or C) by clicking the respective button. For big editing the use of another editor is recommended anyway.

For each equal or different section the editor in the merge result window remembers where it begins or ends. "<No src line>" means that there is nothing left in a section, not even a new line character. This can happen either while merging automatically or by editing. This is no problem, since this hint won't appear in the saved file. If you want the orignal source back just select the section (click on the left summary column) and then click the source button with the needed contents (A/B or C).

KDiff3 already uses many colors for difference highlighting. More highlighting would be confusing. Use another editor for this.

Although KDiff3 will analyse any kind of file the result will probably not be very satisfactory for you.

KDiff3 was made to compare pure text files. OpenOffice.org®, Microsoft® Word, Microsoft® Excel, etc. store much more information in the files (about fonts, pictures, pages, colors, etc.) which KDiff3 doesn't know about. So KDiff3 will show you the contents of the file interpreted as pure text, but this might be unreadable or at least it will look very odd.

Since most programs nowadays store their contents in XML format, you might be able to read it as pure text. So if the change was only small, KDiff3 still might help you.

The best solution if you only want to compare the text (without embedded objects like pictures) is to use Edit → Select All and Edit → Copy menu items in your program to copy the interesting text to the clipboard and then in KDiff3 paste the text into either diff input window. (See also Select, Copy And Paste.)

There are now several "Show" options in the Folder menu. Disabling Show Identical Files will achieve what enabling List only deltas used to do.

Start the selection as usual (click and hold the left mouse button). Then use the navigation keys (e.g. PgUp, PgDn) while holding the left mouse button down. (See also Select, Copy And Paste.)

Please send me your question. I appreciate every comment.