You can grab [the COM component that uses Google&#39;s Diff/Patch/Match][1].  It works from .NET. 

**Update, 2010 Oct 17**: The [Google Diff/Patch/Merge code][2] has been ported to C#.  The COM component still works, but if you&#39;re coming from .NET, you&#39;ll wanna use the .NET port directly. 


  [1]: https://stackoverflow.com/questions/848246/how-can-i-use-javascript-within-an-excel-macro
  [2]: http://code.google.com/p/google-diff-match-patch/

I think the &quot;Generic - Reusable Diff Algorithm in C#&quot; on Codeproject is the best you can find as a .NET-Engine for diff/patch/merge. I made a project on my own with it and it fits my needs with most scenarios. There are one or two worst-case scencario when the algorithm made the patch-file larger than it have to be. But in most of the cases it works just fine for me (textfiles with a size of &gt;30 MB).

I&#39;m currently testing another Codeproject-Project you can find here: http://www.codeproject.com/KB/applications/patch.aspx
It&#39;s using some DLLs from Microsoft for patching, so it looks interesting. But those DLLs are unmanaged and this project is only some sort of wrapper for it. But maybe it can help you

**Edit:**
Just found another project, **DiffPlex**: http://diffplex.codeplex.com/
It&#39;s *a combination of a .NET Diffing Library with both a Silverlight and HTML diff viewer*. As stated [there][1], DiffPlex is the library that CodePlex leverages to generate the diffs of files.

 [1]: https://docs.microsoft.com/en-us/archive/blogs/codeplex/net-4-and-change-set-listing

GitSharp includes a diff engine based on meyers diff. Take a look at the demo which implements a simple wpf diff viewer based on the Diff.Sections collection: http://www.eqqon.com/index.php/GitSharp#GitSharp.Demo

None of the answers so far (except possibly the GitSharp reference) deal with 3-way merge, so in case it helps anyone I recently ported Tony Garnock-Jones&#39; javascript diff3 implementation (from the  [synchrotron][1] project, based on Hunt and McIlroy 1976) to C#.

It&#39;s a simplistic single-file port of diff and three-way merge methods, but it&#39;s the standard algorithm and so far works very well for me: https://gist.github.com/2633407

  [1]: http://homepages.kcbbs.gen.nz/tonyg/projects/synchrotron.html


Sometimes it feels that my company is the only company in the world using Ruby but not Ruby on Rails, to the point that Rails has almost become synonymous with Ruby.

I&#39;m sure this isn&#39;t really true, but it&#39;d be fun to hear some stories about non-Rails Ruby usage out there.

Ruby off the rails

I&#39;ve done some research into server push with javascript and have found the general consensus to be that what I&#39;m looking for lies in the &quot;Comet&quot; design pattern. Are there any good implementations of this pattern built on top of jQuery? If not, are there any good implementations of this pattern at all? And regardless of the answer to those questions, is there any documentation on this pattern from an implementation stand-point?

Comet and jQuery

Requirements:

  - free, preferably open-source
  - implemented in one of the .NET managed langs


Google found these:

  - [A Generic, Reusable Diff
    Algorithm][1] on codeproject
  - [An O(ND) Difference Algorithm for C#][2]
  - [Diff/Merge/Patch Library for C#/.NET][3] by Joshua Tauberer


EDIT:

No apps please, only libraries.

  [1]: http://www.codeproject.com/KB/recipes/diffengine.aspx
  [2]: http://www.mathertel.de/Diff/
  [3]: http://razor.occams.info/code/diff/

Any decent text diff/merge engine for .NET?

Requirements:
<ul>
<li>free, preferably open-source</li>
<li>implemented in one of the .NET managed langs</li>
</ul>
Google found these:
<ul>
<li><a href="http://www.codeproject.com/KB/recipes/diffengine.aspx" target="_blank" rel="noopener noreferrer">A Generic, Reusable Diff
Algorithm</a> on codeproject</li>
<li><a href="http://www.mathertel.de/Diff/" target="_blank" rel="noopener noreferrer">An O(ND) Difference Algorithm for C#</a></li>
<li><a href="http://razor.occams.info/code/diff/" target="_blank" rel="noopener noreferrer">Diff/Merge/Patch Library for C#/.NET</a> by Joshua Tauberer</li>
</ul>
EDIT:
No apps please, only libraries.

I&#39;ve seen both done in some code I&#39;m maintaining, but don&#39;t know the difference. Is there one?

let me add that myCustomer is an instance of Customer

What is the difference between myCustomer.GetType() and typeof(Customer) in C#?

I have a need to convert Pixels to Points in C#. I&#39;ve seen some complicated explanations about the topic, but can&#39;t seem to locate a simple formula. Let&#39;s assume a standard 96dpi, how do I calulate this conversion?

Convert Pixels to Points

This question is not so much programming related as it is deployment related.

I find myself conversing a lot with the group in my company whose job it is to maintain our production Windows servers and deploy our code on them. For legal and compliance reasons, I do not have direct visibility or any control over the servers so the only way I can tell which version(s) of .NET are installed on any of them is through directions I give to that group. 

So far, all of the methods I can think of to tell which version(s) are installed (check for Administrative Tools matching 1.1 or 2.0, check for the entries in the &quot;Add/Remove Programs&quot; list, check for the existence of the directories under c:\Windows\Microsoft.NET) are flawed (I&#39;ve seen at least one machine with 2.0 but no 2.0 entries under Administrative Tools - and that method tells you nothing about 3.0+, the &quot;Add/Remove Programs&quot; list can get out of sync with reality, and the existence of the directories doesn&#39;t necessarily mean anything).

Given that I generally need to know these things are in place in advance (discovering that &quot;oops, this one doesn&#39;t have all the versions and service packs you need&quot; doesn&#39;t really work well with short maintenance windows) and I have to do the checking &quot;by proxy&quot; since I can&#39;t get on the servers directly, what&#39;s the foolproof way to tell which version(s) of .NET are installed on a production Windows Server? Preferably some intrinsic way to do so using what the framework installs since it will be quicker and not need some sort of utility to be loaded and also a method which will definitely fail if the frameworks are not properly installed but still have files in place (i.e., there&#39;s a directory and gacutil.exe is inded there but that version of the framework is not really &quot;installed&quot;)

**EDIT:** In the absence of a good foolproof intrinsic way to do this built into the Framework(s), does anyone know of a good, lightweight, no-install-required program that can find this out? I can imagine someone could easily write one but if one already exists, that would be even better.

What&#39;s the foolproof way to tell which version(s) of .NET are installed on a production Windows Server?

I need to use InstallUtil to install a C# windows service. I need to set the service logon credentials (username and password). All of this needs to be done silently.

Is there are way to do something like this:

    installutil.exe myservice.exe /customarg1=username /customarg2=password



Using InstallUtil and silently setting a windows service logon username/password

If something goes wrong in a WCF REST call, such as the requested resource is not found, how can I play with the HTTP response code (setting it to something like HTTP 404, for example) in my OperationContract method?

How can I return a custom HTTP status code from a WCF REST method?

Is it possible to embed a pre-existing DLL into a compiled C# executable (so that you only have one file to distribute)? If it is possible, how would one go about doing it?

Normally, I&#39;m cool with just leaving the DLLs outside and having the setup program handle everything, but there have been a couple of people at work who have asked me this and I honestly don&#39;t know.

Embedding DLLs in a compiled executable

My motivation for trying out git-svn is the effortless merging and branching. Then I noticed that man git-svn(1) says: 

&gt; Running git-merge or git-pull is NOT recommended on a branch you plan
&gt; to dcommit from. Subversion does not represent merges in any
&gt; reasonable or useful fashion; so users using Subversion cannot see any
&gt; merges you&#39;ve made. Furthermore, if you merge or pull from a git
&gt; branch that is a mirror of an SVN branch, dcommit may commit to the
&gt; wrong branch.

Does this mean I cannot create a local branch from svn/trunk (or a branch), hack away, merge back into svn/trunk, then dcommit? I understand that svn users will see the same mess that merges in svn pre 1.5.x have always been, but are there any other drawbacks? That last sentence worries me, too. Do people routinely do these kinds of things?

Is git-svn dcommit after merging in git dangerous?

The UPSERT operation either updates or inserts a row in a table, depending if the table already has a row that matches the data:

    if table t has a row exists that has key X:
        update t set mystuff... where mykey=X
    else
        insert into t mystuff...

Since Oracle doesn&#39;t have a specific UPSERT statement, what&#39;s the best way to do this?

Oracle: how to UPSERT (update or insert into a table?)

How do you reverse the effect of a merge on polarised branches without dying of agony?

This problem has been plaguing me for **months** and I have finally given up. 


You have 1 Repository, with 2  **Named** Branches.  A and B. 

Changes that occur to A will inevitably occur on B. 

Changes that occur directly on B MUST NEVER occur on A. 

In such a configuration, merging &quot;B&quot; into &quot;A&quot; produces a dire problem in the repository, as all the changes to B appear in A as if they were made in A. 

The only &quot;normal&quot; way to recover from this situation appears to be &quot;backing out&quot; the merge, ie: 

     hg up -r A 
     hg backout -r BadMergeRev --parent BadMergerevBeforeOnA 

Which looks all fine and dandy, until you decide to merge later in the correct direction, and you end up with all sorts of nasty things happening and code that was erased / commented out on specifically branch B suddenly becomes unerased or uncommented. 

There has not been a working viable solution to this so far other than &quot;let it do its thing, and then hand fix all the problems&quot; and that to be honest is a bit fubar.  

Here is an image clarifying the problem: 

*[Original image lost]*

Files C &amp; E ( or changes C &amp; E ) must appear only on branch b, and not on branch a.
Revision A9 here ( branch a, revno 9 ) is the start of the problem. 

Revisions A10 and A11 are the &quot;Backout merge&quot; and &quot;merge the backout&quot; phases. 

And revision B12 is mercurial, erroneously repeatedly dropping a change that was intended  not to be dropped. 

This Dilemma has caused much frustration and blue smoke and I would like to put an end to it. 

&lt;h3&gt;Note&lt;/h3&gt; 
It may be the obvious answer to try prohibiting the reverse merge from occurring, either with hooks or with policies, I have found the ability to muck this up is rather high and the chance of it happening so likely that even with countermeasures, you *must* still assume that inevitably, it *will* happen so that you can solve it when it does.

&lt;h3&gt;To Elaborate&lt;/h3&gt;
In the model I have used Seperate files. These make the problem sound simple. These merely represent *arbitrary changes* which could be a separate line. 

Also, to add insult to injury, there have been substantial changes on branch A which leaves the standing problem &quot;do the changes in branch A conflict with the changes in branch B which just turned up ( and got backed out ) which looks like a change on branch A instead &quot; 

&lt;h3&gt;On History Rewriting Tricks:&lt;/h3&gt;
The problem with all these retro-active solutions is as follows:

   1. We have 9000 commits. 
   2. Cloning freshly thus takes half an hour
   3. If there exists *even one* bad clone of the repository *somewhere*, there is a liklihood of it comming back in contact with the original repository, and banging it up all over again. 
   4. Everyone has cloned this repository already, and now several days have passed with on-going commits.
   5. One such clone, happens to be a live site, so &quot;wiping that one and starting from scratch&quot; = &quot;big nono&quot; 

( I admit, many of the above are a bit daft, but they are outside of my control ). 

The only solutions that are viable are the ones that assume that people *can* and *will* do everything wrong, and that there is a way to &#39;undo&#39; this wrongness. 



Backing Out a backwards merge on Mercurial

What&#39;s the best way to merge 2 or more dictionaries (`Dictionary&lt;T1,T2&gt;`) in C#?
(3.0 features like LINQ are fine).

I&#39;m thinking of a method signature along the lines of:

    public static Dictionary&lt;TKey,TValue&gt;
                     Merge&lt;TKey,TValue&gt;(Dictionary&lt;TKey,TValue&gt;[] dictionaries);

or

    public static Dictionary&lt;TKey,TValue&gt;
                     Merge&lt;TKey,TValue&gt;(IEnumerable&lt;Dictionary&lt;TKey,TValue&gt;&gt; dictionaries);

**EDIT:** Got a cool solution from JaredPar and Jon Skeet, but I was thinking of something that handles duplicate keys. In case of collision, it doesn&#39;t matter which value is saved to the dict as long as it&#39;s consistent.

Merging dictionaries in C#

I&#39;m currently developing an application using a MySQL database.

The database-structure is still in flux and changes while development progresses (I change my local copy, leaving the one on the test-server alone).

Is there a way to compare the two instances of the database to see if there were any changes?

While currently simply discarding the previous test server database is fine, as testing starts entering test data it could get a bit tricky.  
The same though more so will happen again later in production...

Is there an easy way to incrementally make changes to the production database, preferably by automatically creating a script to modify it? 

---

Tools mentioned in the answers:

  - [Red-Gate&#39;s MySQL Schema &amp; Data Compare](https://www.red-gate.com/products/mysql/mysql-compare/) (Commercial)
  - [Maatkit (now Percona)](https://launchpad.net/percona-toolkit)
  - [liquibase](http://www.liquibase.org)
  - [Toad](http://www.quest.com/toad-for-mysql/)
  - [Nob Hill Database Compare](http://nobhillsoft.com/NHDBCompare.aspx) (Commercial)
  - [MySQL Diff](http://adamspiers.org/computing/mysqldiff/)
  - [SQL EDT](http://www.sqledt.com) (Commercial)

Compare two MySQL databases

Every time I do an `hg diff file.ext` I end up using a console diff application. I would like to use Kdiff3 or WinMerge (I&#39;m using Windows).

Is there a way to change that? I can&#39;t find a reference in Mercurial documentation (**I&#39;m not talking about merge!**). 


Is possible to change the default diff tool in Mercurial?

When I type `git diff`, I want to view the output with my visual diff tool of choice (SourceGear &quot;diffmerge&quot; on Windows). How do I configure git to do this?



How do I view &#39;git diff&#39; output with my preferred diff tool/ viewer?

The scenario is:

 1. svn cp or mv some file
 2. modify that file
 3. svn diff &gt; mypatch

On other machine (same working copy, but no changes):

 4. Try to apply mypatch.
 5. Fail -&gt; tries to modify unexistant file.

How can I make svn diff produce patch-appliable patch, or cleanly apply patch produced by svn diff in this case? I can&#39;t commit. I would like to preserve mergeinfo (because the obvious workaround is to add the file as totally new, without connection to the previous one).

How to make svn diff produce file that patch would apply, when svn cp or svn mv was used?

What is the easiest way to highlight the difference between two strings in PHP?

I&#39;m thinking along the lines of the Stack Overflow edit history page, where new text is in green and removed text is in red. If there are any pre-written functions or classes available, that would be ideal.

Content Type	Original Author	Original Content on Stackoverflow
Question	aku	View Question on Stackoverflow
Solution 1 - .Net	Cheeso	View Answer on Stackoverflow
Solution 2 - .Net	Anheledir	View Answer on Stackoverflow
Solution 3 - .Net	henon	View Answer on Stackoverflow
Solution 4 - .Net	Tao	View Answer on Stackoverflow

Any decent text diff/merge engine for .NET?

.Net Problem Overview

.Net Solutions

Solution 1 - .Net

Solution 2 - .Net

Solution 3 - .Net

Solution 4 - .Net

Comet and jQuery

Ruby off the rails

Attributions