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Posted 25 Nov 2008


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How To Update Assembly Version Number Automatically

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4.46/5 (37 votes)
28 Jan 2009CPOL2 min read
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)

Written By
Ukraine Ukraine
Software developer and entrepreneur.

Main projects:
* EasyQuery - ad-hoc data filtering UI for .NET applications;
* Localizer - localization tool kit for Delphi projects;

Comments and Discussions

GeneralMy vote of 5 Pin
David A. Gray18-Jun-22 21:50
MemberDavid A. Gray18-Jun-22 21:50 
I have been seriously remiss in rating your excellent article and the accompanying tool, which has, at long last, become the sole tool that I employ for maintaining AssemblyInfo.cs files in my many C# projects.

Not only have I completely replaced the homegrown program that I used until I discovered yours, but I have significantly improved it to support updating the AssemblyCopyright attribute and to refrain from updating AssemblyInfo.cs when the associated project is unchanged since the last update. The objectives of the latter change are twofold.

1. Reduce build churn that causes assemblies that have many dependents from being unnecessarily rebuilt, causing all of those dependencies to be marked as outdated and rebuilt.

2. Prevent unwarranted and easily avoidable merge conflicts that may arise when two or more people attempt to check code into the same Git repository.

It is past time that I give this code back to the community. To that end, the update is published on GitHub at GitHub - txwizard/AssemblyInfoUtil: This repository incorporates a vastly improved implementation of AssemblyInfoUtil.exe, originally published in 2009 by Sergiy Korzh.[^], with much gratitude to you, @Sergiy Korzh.
GeneralMy vote of 5 Pin
mishrsud5-Sep-16 21:04
professionalmishrsud5-Sep-16 21:04 
QuestionI had modified to allow change InstallShield LE setup Pin
gemese7-Nov-15 7:31
Membergemese7-Nov-15 7:31 
GeneralHelp me lot Pin
panditvishal884-May-15 20:41
Memberpanditvishal884-May-15 20:41 
SuggestionJust an improvement Pin
Thyrador10-Jun-14 23:58
MemberThyrador10-Jun-14 23:58 
GeneralRe: Just an improvement Pin
BostjanSkok6-Nov-14 8:12
MemberBostjanSkok6-Nov-14 8:12 
GeneralRe: Just an improvement Pin
Sergiy Korzh6-Nov-14 10:55
professionalSergiy Korzh6-Nov-14 10:55 
GeneralMy vote of 5 Pin
DeadlyEmbrace2-Sep-13 23:47
MemberDeadlyEmbrace2-Sep-13 23:47 
GeneralMy Vote of 5 Pin
Member 101962197-Aug-13 12:52
MemberMember 101962197-Aug-13 12:52 
GeneralMy vote of 5 Pin
rickist22-Nov-12 5:48
Memberrickist22-Nov-12 5:48 
GeneralMy vote of 5 Pin
_jazz22-Jun-12 2:43
Member_jazz22-Jun-12 2:43 
SuggestionMake it fully automatic with build events Pin
_jazz22-Jun-12 2:33
Member_jazz22-Jun-12 2:33 
QuestionThank you for sharing Pin
mikeperetz14-Mar-12 3:28
Membermikeperetz14-Mar-12 3:28 
SuggestionVersioning Controlled Build Pin
TobiasP7-Mar-12 6:58
MemberTobiasP7-Mar-12 6:58 
AnswerThanks a lot Pin
Sudarsan Srinivasan13-Apr-11 1:39
MemberSudarsan Srinivasan13-Apr-11 1:39 
GeneralBig thanks man Pin
=Quaqmire=13-Mar-11 17:55
Member=Quaqmire=13-Mar-11 17:55 
GeneralMy vote of 5 Pin
lparkd4-Oct-10 6:33
Memberlparkd4-Oct-10 6:33 
GeneralWorks great for me Pin
Michael Elly10-Aug-10 13:52
MemberMichael Elly10-Aug-10 13:52 
GeneralMy vote of 5 Pin
Michael Elly10-Aug-10 13:49
MemberMichael Elly10-Aug-10 13:49 
GeneralTry using regular expressions to parse Pin
mekansm29-Jan-09 7:37
Membermekansm29-Jan-09 7:37 
GeneralSynchronize version number across assemblies Pin
Marc Scheuner29-Jan-09 3:52
professionalMarc Scheuner29-Jan-09 3:52 
GeneralRe: Synchronize version number across assemblies Pin
Don DenUyl3-Feb-09 4:10
MemberDon DenUyl3-Feb-09 4:10 
GeneralNice article Pin
Jeffrey Cameron27-Jan-09 6:04
MemberJeffrey Cameron27-Jan-09 6:04 
GeneralRe: Nice article Pin
Sergiy Korzh27-Jan-09 21:41
professionalSergiy Korzh27-Jan-09 21:41 
QuestionHow To Update Assembly Version Number Automatically Pin
SergiuMD20-Jan-09 23:14
MemberSergiuMD20-Jan-09 23:14 

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