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How To Update Assembly Version Number Automatically

, 28 Jan 2009 CPOL
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A small utility which allows to modify AssemblyVersion attribute specified in AssemblyInfo.cs files

The Problem

I suppose I am not the only one who does not like the version numbers automatically generated by Visual Studio when you specify something like the following in your AssemblyInfo.cs file:

[assembly: AssemblyVersion("2.7.*.*")] 

In the other hand, I would like to specify those numbers automatically during the build process. Moreover it would be great to have an ability to change the whole version number or just increase the latest part of it (build number).  

Of course, you may say that such an operation can simply be done manually. It is true for one or two assemblies. But our usual project contains about 10-15 different assemblies and we would like to have a version number in all of them synchronized.

The Solution

So we need some utility which will perform all the described tasks automatically and which we can call from our build script. The presented simple program allows to change the whole version number in AssemblyInfo files or just increase the number of the build.

To use this program, just call AssemblyInfoUtil.exe with two parameters. The first parameter is the path to AssemblyInfo.cs file that you would like to modify. The second parameter tells the program how to modify the version number attribute. It can be one of the following options:

-set:<New Version Number>

Set the version number to the specified one.

-inc:<Parameter Index>

Simply increase the number of one parameter in version string by 1. Here "Parameter Index" can be any number from 1 to 4. For 1 - the major version number will be increased, for 2 - the minor one and so on.


AssemblyInfoUtil.exe -set: "C:\Program Files\MyProject1\AssemblyInfo.cs"

Set the version string to "".

AssemblyInfoUtil.exe -inc:4 AssemblyInfo.cs

Increase the last (revision) number. So in our case it will become 54.

The Code

So here is the code of this utility. I have published only the content of the Main.cs file. Other project files (like *.csprj) can be found in the attached archive.

using System;
using System.IO;
using System.Text;

namespace AssemblyInfoUtil
    /// <summary>
    /// Summary description for Class1.
    /// </summary>
    class AssemblyInfoUtil
	private static int incParamNum = 0;

	private static string fileName = "";
	private static string versionStr = null;

	private static bool isVB = false;

	/// <summary>
	/// The main entry point for the application.
	/// </summary>
	static void Main(string[] args)
	    for (int i = 0; i < args.Length; i++) {
	        if (args[i].StartsWith("-inc:")) {
		   string s = args[i].Substring("-inc:".Length);
		   incParamNum = int.Parse(s);
	        else if (args[i].StartsWith("-set:")) {
		   versionStr = args[i].Substring("-set:".Length);
		   fileName = args[i];

	    if (Path.GetExtension(fileName).ToLower() == ".vb")
		isVB = true;

	    if (fileName == "") {
		System.Console.WriteLine("Usage: AssemblyInfoUtil 
		    <path to AssemblyInfo.cs or AssemblyInfo.vb file> [options]");
		System.Console.WriteLine("Options: ");
		System.Console.WriteLine("  -set:<new version number> - 
				set new version number (in NN.NN.NN.NN format)");
		System.Console.WriteLine("  -inc:<parameter index>  - 
		   increases the parameter with specified index (can be from 1 to 4)");

	    if (!File.Exists(fileName)) {
			("Error: Can not find file \"" + fileName + "\"");

	    System.Console.Write("Processing \"" + fileName + "\"...");
	    StreamReader reader = new StreamReader(fileName);
             StreamWriter writer = new StreamWriter(fileName + ".out");
	    String line;

	    while ((line = reader.ReadLine()) != null) {
		line = ProcessLine(line);

	    File.Move(fileName + ".out", fileName);

	private static string ProcessLine(string line) {
	    if (isVB) {
		line = ProcessLinePart(line, "<Assembly: AssemblyVersion(\"");
		line = ProcessLinePart(line, "<Assembly: AssemblyFileVersion(\"");
	    else {
		line = ProcessLinePart(line, "[assembly: AssemblyVersion(\"");
		line = ProcessLinePart(line, "[assembly: AssemblyFileVersion(\"");
	    return line;

	private static string ProcessLinePart(string line, string part) {
	    int spos = line.IndexOf(part);
	    if (spos >= 0) {
		spos += part.Length;
		int epos = line.IndexOf('"', spos);
		string oldVersion = line.Substring(spos, epos - spos);
		string newVersion = "";
		bool performChange = false;

		if (incParamNum > 0) {
	  	    string[] nums = oldVersion.Split('.');
		    if (nums.Length >= incParamNum && nums[incParamNum - 1] != "*") {
			Int64 val = Int64.Parse(nums[incParamNum - 1]);
			nums[incParamNum - 1] = val.ToString();
			newVersion = nums[0]; 
			for (int i = 1; i < nums.Length; i++) {
			    newVersion += "." + nums[i];
			performChange = true;
		else if (versionStr != null) {
		    newVersion = versionStr;
		    performChange = true;

		if (performChange) {
		    StringBuilder str = new StringBuilder(line);
		    str.Remove(spos, epos - spos);
		    str.Insert(spos, newVersion);
		    line = str.ToString();
	    return line;


  • 25th November, 2008: Initial post
  • 27th January, 2009: Article update


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Sergiy Korzh
Ukraine Ukraine
Software developer and entrepreneur.
Main projects:
* EasyQuery - ad-hoc data filtering UI for .NET applications;
* Localizer - localization tool kit for Delphi projects;
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Comments and Discussions

SuggestionJust an improvement PinmemberThyrador10-Jun-14 23:58 
GeneralRe: Just an improvement PinmemberBostjanSkok6-Nov-14 8:12 
GeneralRe: Just an improvement PinprofessionalSergiy Korzh6-Nov-14 10:55 
GeneralMy vote of 5 PinmemberCuteD34th2-Sep-13 23:47 
GeneralMy Vote of 5 PinmemberMember 101962197-Aug-13 12:52 
GeneralMy vote of 5 Pinmemberrickist22-Nov-12 5:48 
GeneralMy vote of 5 Pinmember_jazz22-Jun-12 2:43 
SuggestionMake it fully automatic with build events [modified] Pinmember_jazz22-Jun-12 2:33 
QuestionThank you for sharing Pinmembermikeperetz14-Mar-12 3:28 
SuggestionVersioning Controlled Build PinmemberTobiasP7-Mar-12 6:58 
AnswerThanks a lot PinmemberSudarsan Srinivasan13-Apr-11 1:39 
GeneralBig thanks man Pinmemberkfx66613-Mar-11 17:55 
GeneralMy vote of 5 Pinmemberlparkd4-Oct-10 6:33 
GeneralWorks great for me PinmemberMichael Elly10-Aug-10 13:52 
GeneralMy vote of 5 PinmemberMichael Elly10-Aug-10 13:49 
GeneralTry using regular expressions to parse Pinmembermekansm29-Jan-09 7:37 
GeneralSynchronize version number across assemblies PinmemberMarc Scheuner29-Jan-09 3:52 
GeneralRe: Synchronize version number across assemblies PinmemberDon DenUyl3-Feb-09 4:10 
GeneralNice article PinmemberJeffrey Cameron27-Jan-09 6:04 
GeneralRe: Nice article PinmemberSergiy Korzh27-Jan-09 21:41 
QuestionHow To Update Assembly Version Number Automatically PinmemberSergiuMD20-Jan-09 23:14 
GeneralGood article PinmemberDonsw8-Jan-09 11:34 
GeneralThe simple solution PinmemberMike Lang26-Nov-08 10:20 
GeneralAddition to the simple solution PinmemberUrs Enzler1-Dec-08 20:57 
GeneralSearch for similar articles PinmemberCam Birch26-Nov-08 6:56 

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