CAPTCHA Generator for .NET July 25, 2007
Posted by suniljagadish in .NET, C#.4 comments
I needed a CAPTCHA generator for some stuff I’ve been doing. I looked around and did find some assemblies for .NET. I thought of coding my own CAPTCHA generator and decided to do this using C#. The result – You can download/contribute here. You can even download a sample usage of this in a Windows Forms application form the “Releases” section. This can even be used in ASP.NET applications. This assembly will need permission to write to disk (to store the CAPTCHA image generated).
Usage
using CAPTCHA;
CaptchaGenerator cgen;
Single custom coloured CAPTCHA
cgen.CaptchaColor = Color.FromArgb(130, 120, 130);
CaptchaText = cgen.GenerateCaptcha(@”G:\test1.gif”);
pictureBox1.ImageLocation = @”G:\test1.gif”;
Default Random Coloured CAPTCHA
cgen.ResetCaptchaColor();
CaptchaText = cgen.GenerateCaptcha(@”G:\test1.gif”);
pictureBox1.ImageLocation = @”G:\test1.gif”;
Click-O-Matic July 18, 2007
Posted by suniljagadish in .NET, Applications, C#.add a comment
I’ve been downloading software from my MSDN Subscription account. MSDN provides a custom download application which (un)fortunately does not have the feature to schedule downloads to begin at a particular time. Also, I’m not allowed to use DAP or any other download accelrator to download from MSDN. Sharath had pointed me to this sometime back. PTFB is a trial version software, so, here is a free version of a similar (but much more simpler, lesser features & less jing-bang) application which does the same job. I’ve called it Click-O-Matic (for the lack of a better name 
)
A ”just-works” version is ready. In case you are intrested to use this, leave a comment here with your e-mail ID and I can mail the setup file to you.
For the geekier ones here, I wrote this in C# using simple PInvoke to simulate the mouse clicks.
LINQ – Language INtegrated Query June 4, 2006
Posted by suniljagadish in .NET, C#, Programming.add a comment
Language INtegrated Query (LINQ) is an extension to the capabilities of .NET languages (currently C# 3.0 and VB 9.0) to perform SQL-like operations on any source of data. The conventional data sources that we’ve been using today are databases, flat files, XML documents etc. LINQ defines certain standard query operators that enable set operations, traversal, projection, selection, join (the relational algebra stuff) to be performed on non-conventional sources of data, which is IEnumerable<T>-based. This means that you can use LINQ to query data from sources such as the enumeration of the list of processes running on your machine. I found this neat example here.
To get started with LINQ, you need to download the LINQ SDK (May 2006). I delivered a session on LINQ at the BDotNETStudent UG meet.
One of my demos included querying a String collection.
Code:
string[] names = {"Burke", "Connor", "Frank", "Everett", "Albert", "George", "Harris", "David"};
var q = names
.Where(s => s.Length > 4)
.OrderBy(s => s.Length)
.Select(s => s);
foreach(var i in q)
Console.WriteLine(i);
A simple query which selects those names from the collection which have a length greater than 4 and the same is then ordered based on the length of each string (in ascending order).
The output:
Frank
David
Burke
George
Harris
Connor
Albert
Everett
Here you’d observe that though “Burke” appears before “Frank” in the original collection, after the execution of the query, the order isn’t preserved. This is because; the OrderBy operator implements an unstable sort algorithm to order the elements.The subtle difference between OrderBy in LINQ and SQL is that, in case of SQL, a query like-
select * from tab_names order by len(sname)
would result in:
Burke
Frank
David
Albert
George
Harris
Connor
Everett
Links:
LINQ Project on MSDN
Download LINQ SDK
LINQ Samples
Anders Hejlsberg on LINQ [Channel9 video]
LINQ Intro
