Chinh's semi-random thoughts on software development, gadgets, and other things.

I was looking for the most efficient way to remove excess white space from a string and wrote the following benchmark. Guess which algorithm is faster?

const int iterations = 200000;
const string expr = " Hello    world! Why    are so    many spaces?  Testing One   two three    four    five.";

// Remove excess space using Regex
var doRegex = new Action(() =>
{
    for (int i = 0; i < iterations; i++)
    {
        var newStr = Regex.Replace(expr, @"\s{2,}", " ");
    }
});


// Remove excess space using Split/Join
var doSplit = new Action(() =>
{
    for (int i = 0; i < iterations; i++)
    {
        var newStr = String.Join(" ", expr.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries));
    }
});

var benchMark = new Func<string, Action, long>((name, a) => {
    var sw = Stopwatch.StartNew();
    a();
    sw.Stop();
    Console.WriteLine(name + ": " + sw.ElapsedMilliseconds);
    return sw.ElapsedMilliseconds;
});

// Warming up
Console.WriteLine("Warming up.");
doRegex();
doSplit();

// Run benchmark
long regexElapsed = benchMark("Regex", doRegex);
long splitElapsed = benchMark("Split", doSplit);

On my PC, the Split method is about 7.5 times faster than Regex.

Version 1.2 of Transactional File Manager is now available on CodePlex.

Here’s the release notes:

Release Notes

This is a minor bug-fix/minor refactor release.
Fixes:

• Copy now uses the overwrite parameter correctly.
• Fixes crashing problem on some machines due to use of GetsequentialGuid.
• CreateDirectory now supports rolling back nested directories.
• RollbackFile Rollback() may throw exception when original directory has been deleted.
• Security issue when writing to event logs.

Enhancements:

• Upgrade solution/project files to Visual Studio 2010
• Use NUnit instead of VSTS framework
• Changes to support Visual Studio Express

Thanks to karbuke and dorong for their contributions.

From my code snippets, here’s a function that will return the starting day of the week for any date:

/// <summary>
/// Gets the start of the week that contains the specified date.
/// </summary>
/// <param name="date">The date.</param>
/// <param name="weekStartsOn">The day that each week starts on.</param>
/// <returns>The start date of the week.</returns>
public static DateTime GetStartOfWeek(DateTime date, DayOfWeek weekStartsOn)
{
    int days = date.DayOfWeek - weekStartsOn;
    DateTime startOfWeek = days>=0 ? date.AddDays(-days) : date.AddDays(-7 - days);
    return startOfWeek;
}

It’s my first open source project! I’ve gone open source with my Transactional File Manager. Check out the CodePlex link here.

Use any file system as a transactional file system! Transactional File Manager is a .NET API that supports including file system operations such as file copy, move, delete in a transaction. It’s an implementation of System.Transaction.IEnlistmentNotification (works with System.Transactions.TransactionScope).

More on Transactional File Manager in my original blog post on it. If you are interested in contributing to the project, let me know.