AssemblyVersion and AssemblyFileVersion

See here
and here

• AssemblyVersion is .NET version info whilst 'AssemblyFileVersion' is Windows version number, ie., what you see when you do view the file properties of an assembly in windows explorer. AssemblyVersion defines the version other assemblies are compiled against in their manifest.
• If 'AssemblyFileVersion' attribute is not present in 'AssemblyInfo.cs' then AssemblyFileVesrion takes the same value as AssemblyVersion.

Assembly Version Incrementor

Find and increment the assembly version info in an Assembly info file

public class AssemblyVersionIncrementor
{
    public void IncrementAssemblyVersionString(FileSystemInfo fileInfo)
    {
        string[] lines = File.ReadAllLines(fileInfo.FullName);
        lines = IncrementAssemblyVersionString(lines);
        File.WriteAllLines(fileInfo.FullName, lines);
    }

    internal string[] IncrementAssemblyVersionString(string[] lines)
    {
        string[] res = new string[lines.Length];
        int ix = 0;
        foreach (string line in lines)
        {
            res[ix++] = IncrementAssemblyVersionString(line);
        }
        return res;
    }

    // Could be modified to find other types of Version Info by
    // making the "AssemblyVersion" a parameter
    internal string IncrementAssemblyVersionString(string line)
    {
        string res = line;
        if (line.Contains("AssemblyVersion"))
        {
            string newLine = string.Empty;
            string str = line;
            // Check for comments
            int commentStart = line.IndexOf("//");
            // TODO /* ... */ style comments
            if (commentStart >= 0)
            {
                str = line.Substring(0, commentStart);
            }
            if (str.Contains("AssemblyVersion"))
            {
                int start = str.IndexOf('"') + 1;
                int end = str.IndexOf('"', start);
                string assemblyVerStr = str.Substring(start, end - start);
                Version av = new Version(assemblyVerStr);
                Version newVer = av.IncrementRevision();
                newLine = line.Substring(0, start) + newVer.ToString() + 
                    line.Substring(end, line.Length - end);
            }

            res = newLine.Length > 0 ? newLine : line;
        }

        return res;
    }
}

uses the following Version extension class:

internal static class VersionExtender
{
    public static Version Increment(this Version version)
    {
        return Increment(version, 0x1L);
    }

    public static Version IncrementMajor(this Version version)
    {
        return Increment(version, 0x1000000000000L);
    }

    public static Version IncrementMinor(this Version version)
    {
        return Increment(version, 0x100000000L);
    }

    public static Version IncrementBuild(this Version version)
    {
        return Increment(version, 0x10000L);
    }

    public static Version IncrementRevision(this Version version)
    {
        return Increment(version, 0x1L);
    }


    // Good demo of using >> and << operators as well
    private static Version Increment(this Version version, ulong inc)
    {
        ulong versnNum = (((ulong)version.Major & 0xFFFF) << 48) +
            (((ulong)version.Minor & 0xFFFF) << 32) +
            (((ulong)version.Build & 0xFFFF) << 16) +
            ((ulong)version.Revision & 0xFFFF);

        versnNum += inc;

        UInt16 major = (UInt16)(versnNum >> 48);
        UInt16 minor = (UInt16)((versnNum >> 32) & 0xFFFF);
        UInt16 build = (UInt16)((versnNum >> 16) & 0xFFFF);
        UInt16 revision = (UInt16)(versnNum & 0xFFFF);

        return new Version(major, minor, build, revision);
    }
}