Displaying the build date

Question

I currently have an app displaying the build number in its title window. That's well and good except it means nothing to most of the users, who want to know if they have the latest build - they tend to refer to it as "last Thursday's" rather than build 1.0.8.4321.

The plan is to put the build date there instead - So "App built on 21/10/2009" for example.

I'm struggling to find a programmatic way to pull the build date out as a text string for use like this.

For the build number, I used:

Assembly.GetExecutingAssembly().GetName().Version.ToString()

after defining how those came up.

I'd like something like that for the compile date (and time, for bonus points).

Pointers here much appreciated (excuse pun if appropriate), or neater solutions...

Answer 1

Jeff Atwood had a few things to say about this issue in Determining Build Date the hard way.

The most reliable method turns out to be retrieving the linker timestamp from the PE header embedded in the executable file -- some C# code (by Joe Spivey) for that from the comments to Jeff's article:

public static DateTime GetLinkerTime(this Assembly assembly, TimeZoneInfo target = null)
{
    var filePath = assembly.Location;
    const int c_PeHeaderOffset = 60;
    const int c_LinkerTimestampOffset = 8;

    var buffer = new byte[2048];

    using (var stream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
        stream.Read(buffer, 0, 2048);

    var offset = BitConverter.ToInt32(buffer, c_PeHeaderOffset);
    var secondsSince1970 = BitConverter.ToInt32(buffer, offset + c_LinkerTimestampOffset);
    var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

    var linkTimeUtc = epoch.AddSeconds(secondsSince1970);

    var tz = target ?? TimeZoneInfo.Local;
    var localTime = TimeZoneInfo.ConvertTimeFromUtc(linkTimeUtc, tz);

    return localTime;
}

Usage example:

var linkTimeLocal = Assembly.GetExecutingAssembly().GetLinkerTime();

UPDATE: The method was working for .Net Core 1.0, but stopped working after .Net Core 1.1 release(gives random years in 1900-2020 range)

Answer 2

Add below to pre-build event command line:

echo %date% %time% > "$(ProjectDir)\Resources\BuildDate.txt"

Add this file as resource, now you have 'BuildDate' string in your resources.

To create resources, see How to create and use resources in .NET.

Answer 3

The way

As pointed out by @c00000fd in the comments. Microsoft is changing this. And while many people don't use the latest version of their compiler I suspect this change makes this approach unquestionably bad. And while it's a fun exercise I would recommend people to simply embed a build date into their binary through any other means necessary if it's important to track the build date of the binary itself.

This can be done with some trivial code generation which probably is the first step in your build script already. That, and the fact that ALM/Build/DevOps tools help a lot with this and should be preferred to anything else.

I leave the rest of this answer here for historical purposes only.

The new way

I changed my mind about this, and currently use this trick to get the correct build date.

#region Gets the build date and time (by reading the COFF header)

// http://msdn.microsoft.com/en-us/library/ms680313

struct _IMAGE_FILE_HEADER
{
    public ushort Machine;
    public ushort NumberOfSections;
    public uint TimeDateStamp;
    public uint PointerToSymbolTable;
    public uint NumberOfSymbols;
    public ushort SizeOfOptionalHeader;
    public ushort Characteristics;
};

static DateTime GetBuildDateTime(Assembly assembly)
{
    var path = assembly.GetName().CodeBase;
    if (File.Exists(path))
    {
        var buffer = new byte[Math.Max(Marshal.SizeOf(typeof(_IMAGE_FILE_HEADER)), 4)];
        using (var fileStream = new FileStream(path, FileMode.Open, FileAccess.Read))
        {
            fileStream.Position = 0x3C;
            fileStream.Read(buffer, 0, 4);
            fileStream.Position = BitConverter.ToUInt32(buffer, 0); // COFF header offset
            fileStream.Read(buffer, 0, 4); // "PE\0\0"
            fileStream.Read(buffer, 0, buffer.Length);
        }
        var pinnedBuffer = GCHandle.Alloc(buffer, GCHandleType.Pinned);
        try
        {
            var coffHeader = (_IMAGE_FILE_HEADER)Marshal.PtrToStructure(pinnedBuffer.AddrOfPinnedObject(), typeof(_IMAGE_FILE_HEADER));

            return TimeZone.CurrentTimeZone.ToLocalTime(new DateTime(1970, 1, 1) + new TimeSpan(coffHeader.TimeDateStamp * TimeSpan.TicksPerSecond));
        }
        finally
        {
            pinnedBuffer.Free();
        }
    }
    return new DateTime();
}

#endregion

The old way

Well, how do you generate build numbers? Visual Studio (or the C# compiler) actually provides automatic build and revision numbers if you change the AssemblyVersion attribute to e.g. 1.0.*

What will happen is that is that the build will be equal to the number of days since January 1, 2000 local time, and for revision to be equal to the number of seconds since midnight local time, divided by 2.

see Community Content, Automatic Build and Revision numbers

e.g. AssemblyInfo.cs

[assembly: AssemblyVersion("1.0.*")] // important: use wildcard for build and revision numbers!

SampleCode.cs

var version = Assembly.GetEntryAssembly().GetName().Version;
var buildDateTime = new DateTime(2000, 1, 1).Add(new TimeSpan(
TimeSpan.TicksPerDay * version.Build + // days since 1 January 2000
TimeSpan.TicksPerSecond * 2 * version.Revision)); // seconds since midnight, (multiply by 2 to get original)

Answer 4

Add below to pre-build event command line:

echo %date% %time% > "$(ProjectDir)\Resources\BuildDate.txt"

Add this file as resource, now you have 'BuildDate' string in your resources.

After inserting the file into the Resource (as public text file), I accessed it via

string strCompTime = Properties.Resources.BuildDate;

To create resources, see How to create and use resources in .NET.

Answer 5

One approach which I'm amazed no-one has mentioned yet is to use T4 Text Templates for code generation.

<#@ template debug="false" hostspecific="true" language="C#" #>
<#@ assembly name="System.Core" #>
<#@ import namespace="System" #>
<#@ output extension=".g.cs" #>
using System;
namespace Foo.Bar
{
    public static partial class Constants
    {
        public static DateTime CompilationTimestampUtc { get { return new DateTime(<# Write(DateTime.UtcNow.Ticks.ToString()); #>L, DateTimeKind.Utc); } }
    }
}

Pros:

• Locale-independent
• Allows a lot more than just the time of compilation

Cons:

• Only applicable to libraries where you control the source
• Requires configuring your project (and build server, if that doesn't pick it up) to execute the template in a pre-build step. (See also T4 without VS).

Answer 6

Lots of great answers here but I feel like I can add my own because of simplicity, performance (comparing to resource-related solutions) cross platform (works with Net Core too) and avoidance of any 3rd party tool. Just add this msbuild target to the csproj.

<Target Name="Date" BeforeTargets="BeforeBuild">
    <WriteLinesToFile File="$(IntermediateOutputPath)gen.cs" Lines="static partial class Builtin { public static long CompileTime = $([System.DateTime]::UtcNow.Ticks) %3B }" Overwrite="true" />
    <ItemGroup>
        <Compile Include="$(IntermediateOutputPath)gen.cs" />
    </ItemGroup>
</Target>

and now you have Builtin.CompileTime in this project, e.g.:

var compileTime = new DateTime(Builtin.CompileTime, DateTimeKind.Utc);

ReSharper is not gonna like it. You can ignore him or add a partial class to the project too but it works anyway.

UPD: Nowadays ReSharper have an option in a first page of Options: "MSBuild access", "Obtain data from MSBuild after each compilation". This helps with visibility of generated code.

Answer 7

Regarding the technique of pulling build date/version info from the bytes of an assembly PE header, Microsoft has changed the default build parameters beginning with Visual Studio 15.4. The new default includes deterministic compilation, which makes a valid timestamp and automatically incremented version numbers a thing of the past. The timestamp field is still present but it gets filled with a permanent value that is a hash of something or other, but not any indication of the build time.

Some detailed background here

For those who prioritize a useful timestamp over deterministic compilation, there is a way to override the new default. You can include a tag in the .csproj file of the assembly of interest as follows:

  <PropertyGroup>
      ...
      <Deterministic>false</Deterministic>
  </PropertyGroup>

Update: I endorse the T4 text template solution described in another answer here. I used it to solve my issue cleanly without losing the benefit of deterministic compilation. One caution about it is that Visual Studio only runs the T4 compiler when the .tt file is saved, not at build time. This can be awkward if you exclude the .cs result from source control (since you expect it to be generated) and another developer checks out the code. Without resaving, they won't have the .cs file. There is a package on nuget (I think called AutoT4) that makes T4 compilation part of every build. I have not yet confronted the solution to this during production deployment, but I expect something similar to make it right.

Answer 8

I am just C# newbie so maybe my answer sound silly - I display the build date from the date the executable file was last written to:

string w_file = "MyProgram.exe"; 
string w_directory = Directory.GetCurrentDirectory();

DateTime c3 =  File.GetLastWriteTime(System.IO.Path.Combine(w_directory, w_file));
RTB_info.AppendText("Program created at: " + c3.ToString());

I tried to use File.GetCreationTime method but got weird results: the date from the command was 2012-05-29, but the date from the Window Explorer showed 2012-05-23. After searching for this discrepancy I found that the file was probably created on 2012-05-23 (as shown by Windows Explorer), but copied to the current folder on 2012-05-29 (as shown by File.GetCreationTime command) - so to be on the safe side I am using File.GetLastWriteTime command.

Zalek

Answer 9

For .NET Core projects, I adapted Postlagerkarte's answer to update the assembly Copyright field with the build date.

Directly Edit csproj

The following can be added directly to the first PropertyGroup in the csproj:

<Copyright>Copyright © $([System.DateTime]::UtcNow.Year) Travis Troyer ($([System.DateTime]::UtcNow.ToString("s")))</Copyright>

Alternative: Visual Studio Project Properties

Or paste the inner expression directly into the Copyright field in the Package section of the project properties in Visual Studio:

Copyright © $([System.DateTime]::UtcNow.Year) Travis Troyer ($([System.DateTime]::UtcNow.ToString("s")))

This can be a little confusing, because Visual Studio will evaluate the expression and display the current value in the window, but it will also update the project file appropriately behind the scenes.

Solution-wide via Directory.Build.props

You can plop the <Copyright> element above into a Directory.Build.props file in your solution root, and have it automatically applied to all projects within the directory, assuming each project does not supply its own Copyright value.

<Project>
 <PropertyGroup>
   <Copyright>Copyright © $([System.DateTime]::UtcNow.Year) Travis Troyer ($([System.DateTime]::UtcNow.ToString("s")))</Copyright>
 </PropertyGroup>
</Project>

Directory.Build.props: Customize your build

Output

The example expression will give you a copyright like this:

Copyright © 2018 Travis Troyer (2018-05-30T14:46:23)

Retrieval

You can view the copyright information from the file properties in Windows, or grab it at runtime:

var version = FileVersionInfo.GetVersionInfo(Assembly.GetEntryAssembly().Location);

Console.WriteLine(version.LegalCopyright);

Answer 10

The above method can be tweaked for assemblies already loaded within the process by using the file's image in memory (as opposed to re-reading it from storage):

using System;
using System.Runtime.InteropServices;
using Assembly = System.Reflection.Assembly;

static class Utils
{
    public static DateTime GetLinkerDateTime(this Assembly assembly, TimeZoneInfo tzi = null)
    {
        // Constants related to the Windows PE file format.
        const int PE_HEADER_OFFSET = 60;
        const int LINKER_TIMESTAMP_OFFSET = 8;

        // Discover the base memory address where our assembly is loaded
        var entryModule = assembly.ManifestModule;
        var hMod = Marshal.GetHINSTANCE(entryModule);
        if (hMod == IntPtr.Zero - 1) throw new Exception("Failed to get HINSTANCE.");

        // Read the linker timestamp
        var offset = Marshal.ReadInt32(hMod, PE_HEADER_OFFSET);
        var secondsSince1970 = Marshal.ReadInt32(hMod, offset + LINKER_TIMESTAMP_OFFSET);

        // Convert the timestamp to a DateTime
        var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
        var linkTimeUtc = epoch.AddSeconds(secondsSince1970);
        var dt = TimeZoneInfo.ConvertTimeFromUtc(linkTimeUtc, tzi ?? TimeZoneInfo.Local);
        return dt;
    }
}

Answer 11

In 2018 some of the above solutions do not work anymore or do not work with .NET Core.

I use the following approach which is simple and works for my .NET Core 2.0 project.

Add the following to your .csproj inside the PropertyGroup :

    <Today>$([System.DateTime]::Now)</Today>

This defines a PropertyFunction which you can access in your pre build command.

Your pre-build looks like this

echo $(today) > $(ProjectDir)BuildTimeStamp.txt

Set the property of the BuildTimeStamp.txt to Embedded resource.

Now you can read the time stamp like this

public static class BuildTimeStamp
    {
        public static string GetTimestamp()
        {
            var assembly = Assembly.GetEntryAssembly(); 

            var stream = assembly.GetManifestResourceStream("NamespaceGoesHere.BuildTimeStamp.txt");

            using (var reader = new StreamReader(stream))
            {
                return reader.ReadToEnd();
            }
        }
    }

Answer 12

For anyone that needs to get the compile time in Windows 8 / Windows Phone 8:

    public static async Task<DateTimeOffset?> RetrieveLinkerTimestamp(Assembly assembly)
    {
        var pkg = Windows.ApplicationModel.Package.Current;
        if (null == pkg)
        {
            return null;
        }

        var assemblyFile = await pkg.InstalledLocation.GetFileAsync(assembly.ManifestModule.Name);
        if (null == assemblyFile)
        {
            return null;
        }

        using (var stream = await assemblyFile.OpenSequentialReadAsync())
        {
            using (var reader = new DataReader(stream))
            {
                const int PeHeaderOffset = 60;
                const int LinkerTimestampOffset = 8;

                //read first 2048 bytes from the assembly file.
                byte[] b = new byte[2048];
                await reader.LoadAsync((uint)b.Length);
                reader.ReadBytes(b);
                reader.DetachStream();

                //get the pe header offset
                int i = System.BitConverter.ToInt32(b, PeHeaderOffset);

                //read the linker timestamp from the PE header
                int secondsSince1970 = System.BitConverter.ToInt32(b, i + LinkerTimestampOffset);

                var dt = new DateTimeOffset(1970, 1, 1, 0, 0, 0, DateTimeOffset.Now.Offset) + DateTimeOffset.Now.Offset;
                return dt.AddSeconds(secondsSince1970);
            }
        }
    }

For anyone that needs to get the compile time in Windows Phone 7:

    public static async Task<DateTimeOffset?> RetrieveLinkerTimestampAsync(Assembly assembly)
    {
        const int PeHeaderOffset = 60;
        const int LinkerTimestampOffset = 8;            
        byte[] b = new byte[2048];

        try
        {
            var rs = Application.GetResourceStream(new Uri(assembly.ManifestModule.Name, UriKind.Relative));
            using (var s = rs.Stream)
            {
                var asyncResult = s.BeginRead(b, 0, b.Length, null, null);
                int bytesRead = await Task.Factory.FromAsync<int>(asyncResult, s.EndRead);
            }
        }
        catch (System.IO.IOException)
        {
            return null;
        }

        int i = System.BitConverter.ToInt32(b, PeHeaderOffset);
        int secondsSince1970 = System.BitConverter.ToInt32(b, i + LinkerTimestampOffset);
        var dt = new DateTimeOffset(1970, 1, 1, 0, 0, 0, DateTimeOffset.Now.Offset) + DateTimeOffset.Now.Offset;
        dt = dt.AddSeconds(secondsSince1970);
        return dt;
    }

NOTE: In all cases you're running in a sandbox, so you'll only be able to get the compile time of assemblies that you deploy with your app. (i.e. this won't work on anything in the GAC).

Answer 13

I just do:

File.GetCreationTime(GetType().Assembly.Location)

Answer 14

The option not discussed here is to insert your own data into AssemblyInfo.cs, the "AssemblyInformationalVersion" field seems appropriate - we have a couple of projects where we were doing something similar as a build step (however I'm not entirely happy with the way that works so don't really want to reproduce what we've got).

There's an article on the subject on codeproject: http://www.codeproject.com/KB/dotnet/Customizing_csproj_files.aspx

Answer 15

I needed a universal solution that worked with a NETStandard project on any platform (iOS, Android, and Windows.) To accomplish this, I decided to automatically generate a CS file via a PowerShell script. Here is the PowerShell script:

param($outputFile="BuildDate.cs")

$buildDate = Get-Date -date (Get-Date).ToUniversalTime() -Format o
$class = 
"using System;
using System.Globalization;

namespace MyNamespace
{
    public static class BuildDate
    {
        public const string BuildDateString = `"$buildDate`";
        public static readonly DateTime BuildDateUtc = DateTime.Parse(BuildDateString, null, DateTimeStyles.AssumeUniversal | DateTimeStyles.AdjustToUniversal);
    }
}"

Set-Content -Path $outputFile -Value $class

Save the PowerScript file as GenBuildDate.ps1 and add it your project. Finally, add the following line to your Pre-Build event:

powershell -File $(ProjectDir)GenBuildDate.ps1 -outputFile $(ProjectDir)BuildDate.cs

Make sure BuildDate.cs is included in your project. Works like a champ on any OS!

Answer 16

A different, PCL-friendly approach would be to use an MSBuild inline task to substitute the build time into a string that is returned by a property on the app. We are using this approach successfully in an app that has Xamarin.Forms, Xamarin.Android, and Xamarin.iOS projects.

EDIT:

Simplified by moving all of the logic into the SetBuildDate.targets file, and using Regex instead of simple string replace so that the file can be modified by each build without a "reset".

The MSBuild inline task definition (saved in a SetBuildDate.targets file local to the Xamarin.Forms project for this example):

<Project xmlns='http://schemas.microsoft.com/developer/msbuild/2003' ToolsVersion="12.0">

  <UsingTask TaskName="SetBuildDate" TaskFactory="CodeTaskFactory" 
    AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v12.0.dll">
    <ParameterGroup>
      <FilePath ParameterType="System.String" Required="true" />
    </ParameterGroup>
    <Task>
      <Code Type="Fragment" Language="cs"><![CDATA[

        DateTime now = DateTime.UtcNow;
        string buildDate = now.ToString("F");
        string replacement = string.Format("BuildDate => \"{0}\"", buildDate);
        string pattern = @"BuildDate => ""([^""]*)""";
        string content = File.ReadAllText(FilePath);
        System.Text.RegularExpressions.Regex rgx = new System.Text.RegularExpressions.Regex(pattern);
        content = rgx.Replace(content, replacement);
        File.WriteAllText(FilePath, content);
        File.SetLastWriteTimeUtc(FilePath, now);

   ]]></Code>
    </Task>
  </UsingTask>

</Project>

Invoking the above inline task in the Xamarin.Forms csproj file in target BeforeBuild:

  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
       Other similar extension points exist, see Microsoft.Common.targets.  -->
  <Import Project="SetBuildDate.targets" />
  <Target Name="BeforeBuild">
    <SetBuildDate FilePath="$(MSBuildProjectDirectory)\BuildMetadata.cs" />
  </Target>

The FilePath property is set to a BuildMetadata.cs file in the Xamarin.Forms project that contains a simple class with a string property BuildDate, into which the build time will be substituted:

public class BuildMetadata
{
    public static string BuildDate => "This can be any arbitrary string";
}

Add this file BuildMetadata.cs to project. It will be modified by every build, but in a manner that allows repeated builds (repeated replacements), so you may include or omit it in source control as desired.

Answer 17

You can use this project: https://github.com/dwcullop/BuildInfo

It leverages T4 to automate the build date timestamp. There are several versions (different branches) including one that gives you the Git Hash of the currently checked out branch, if you're into that sort of thing.

Disclosure: I wrote the module.

Answer 18

A small update on the "New Way" answer from Jhon.

You need to build the path instead of using the CodeBase string when working with ASP.NET/MVC

    var codeBase = assembly.GetName().CodeBase;
    UriBuilder uri = new UriBuilder(codeBase);
    string path = Uri.UnescapeDataString(uri.Path);

Answer 19

I'm not sure, but maybe the Build Incrementer helps.

Answer 20

You could use a project post-build event to write a text file to your target directory with the current datetime. You could then read the value at run-time. It's a little hacky, but it should work.

Answer 21

I used Abdurrahim's suggestion. However, it seemed to give a weird time format and also added the abbreviation for the day as part of the build date; example: Sun 12/24/2017 13:21:05.43. I only needed just the date so I had to eliminate the rest using substring.

After adding the echo %date% %time% > "$(ProjectDir)\Resources\BuildDate.txt"to the pre-build event, I just did the following:

string strBuildDate = YourNamespace.Properties.Resources.BuildDate;
string strTrimBuildDate = strBuildDate.Substring(4).Remove(10);

The good news here is that it worked.

Answer 22

You could launch an extra step in the build process that writes a date stamp to a file which can then be displayed.

On the projects properties tab look at the build events tab. There is an option to execute a pre or post build command.

Answer 23

I just added pre-build event command:

powershell -Command Get-Date -Format 'yyyy-MM-ddTHH:mm:sszzz' > Resources\BuildDateTime.txt

in the project properties to generate a resource file that is then easy to read from the code.

Answer 24

I had difficulties with the suggested solutions with my project, a .Net Core 2.1 web application. I combined various suggestions from above and simplified, and also converted the date to my required format.

The echo command:

echo Build %DATE:~-4%/%DATE:~-10,2%/%DATE:~-7,2% %time% > "$(ProjectDir)\BuildDate.txt"

The code:

Logger.Info(File.ReadAllText(@"./BuildDate.txt").Trim());

It seems to work. The output:

2021-03-25 18:41:40,877 [1] INFO Config - Build 2021/03/25 18:41:37.58

Nothing very original, I just combined suggestions from here and other related questions, and simplified.

Answer 25

If this is a windows app, you can just use the application executable path: new System.IO.FileInfo(Application.ExecutablePath).LastWriteTime.ToString("yyyy.MM.dd")

Answer 26

it could be Assembly execAssembly = Assembly.GetExecutingAssembly(); var creationTime = new FileInfo(execAssembly.Location).CreationTime; // "2019-09-08T14:29:12.2286642-04:00"