ganshani.com » C#

Ten Traps in C# for C++ Programmers

Punit Ganshani — Fri, 24 Jul 2009 12:03:19 +0000

Though this boils down to basics, these are most often missed out in projects and hence are performance issues.

http://ondotnet.com/pub/a/oreilly/dotnet/news/programmingCsharp_0801.html

The author has very beautifully touched on topics like:

Destructors
Dispose and Finalize
Value & Reference Types
Boxing
Structures
Virtual methods
and many more…

A must read for newbies…

Interface vs Object vs Aspect Oriented Programming

Punit Ganshani — Tue, 30 Jun 2009 12:14:44 +0000

Interface oriented is something like having contract-based approach, means whatsoever be there under the Contract you have to implement all of it. A good example of this is : WCF.

Object oriented is based on

1. abstraction – which means making things loosely coupled so that in future they can be easily handled without affecting the system.

2. encapsulation(data hiding) – categorizing data as per their role i.e private, public, etc.

3. inheritance – provides the real world genetic mechanism as what’s there in the parent would be there in the child too(or not).

4. and polymorphism – means same look and feel but different functional abiltity.

Aspect oriented programming can be done either on Interface oriented or an Object oriented code. It can not exist alone. AOP is another method of reducing the redundant code and its impact. Let’s see an example:

You have a class ResultGraph in a Stock Application, which has say 5 methods (like MethodA, MethodB, MethodC, MethodD, UpdateGraphics).

Assume that just after a method (say, MethodX) is executed, the stock price changes – hence the graph needs to be re-rendered. In such case, UpdateGraphics needs to be called. Which means all 5 functions will call UpdateGraphics.

This appears to be simple since the number of functions is less. In a real time scenario, there are 100’s of methods and implementing this becomes tough.

AOP enables doing it in an easier manner. We write something like:-

after() : set() {
ResultGraph.UpdateGraphics();
}

pointcut set() : execution(* set*(*) ) && this(StockClass) && within(com.company.*);

The first code means, whenever any set is called, call ResultGraph.UpdateGraphics()

The second code interprets as,

if a method is named set*:(* means any name might follow after set), regardless of what the method returns (first asterisk) or what parameters it takes (third asterisk) and it is a method of StockClass and this class is part of the package “com.company.*”, then this is a set() pointcut. And our first code says “after running any method that is a set pointcut, run the following code”.

I hope now the difference is clear…

Exception Message Box in C#

Punit Ganshani — Tue, 24 Feb 2009 09:01:47 +0000

Its time to forget the old traditional message box with limited functionalities. buttons, icons, text area and what not! Microsoft has unleashed a new message box – new, yet not so new.

For those who have used SQL Sever 2005 GUI, might have probably noticed a message box that shows additional information, copying the text to clipboard, a checkbox on message box, different set of buttons and many more features. This message box is now open for reuse in your applications.

This is not a ‘big-bang’ release made by Microsoft. It has come out very quietly. Yes the name ‘ExceptionMessageBox’ is confusing – but you can still use it in your applications. This standalone exception dialog box can be used in applications just like any other managed APIs.

Probably, you never know the next version of myTracker may use this message box too

Let’s hear it from Microsoft:

The exception message box is a programmatic interface that you can use in your applications for any tasks for which MessageBox may be used. The exception message box is a supported managed assembly designed to elegantly handle managed code exceptions. It provides significantly more control over the messaging experience and gives your users the options to save error message content for later reference and to get help on messages.

Download Link:

http://download.microsoft.com/download/f/7/4/f74cbdb1-87e2-4794-9186-e3ad6bd54b41/SQLServer2005_EMB.msi

Using Smart Client with Enterprise Library 4

Punit Ganshani — Sat, 29 Nov 2008 15:09:08 +0000

Wow! Compatibility between SCSF and EL 4 has troubled me many a times in some of my critical projects. Visual Studio 2008 does not allow installation of EL 3.1 and SCSF is based on EL 3.1.

To install EL 4.0 and to make it compatible with SCSF on VS2008 – here are the steps:

1. Rebuild Block Assemblies
2. Update Guidance Package
3. Update SCSF Application

Rebuild Block Assemblies

1. Extract the Smart Client Software Factory Source Code.

2. Open the SmartClient.Offline solution located at the source code installation folder.

3. Remove from the SmartClient.EnterpriseLibrary and SmartClient.EnterpriseLibrary.Tests projects the references to the following assemblies:

   – Microsoft.Practices.EnterpriseLibrary.Common
   -  Microsoft.Practices.EnterpriseLibrary.Data
   – SmartClient.EnterpriseLibrary.Data.SqlCe

4. Add, In the SmartClient.EnterpriseLibrary and SmartClient.EnterpriseLibrary.Tests projects, references to the following Enterprise Library assemblies (located at Enterprise Library assemblies located at %Enterprise Library 4 installation folder%\Bin):

   – Microsoft.Practices.EnterpriseLibrary.Common.dll
   – Microsoft.Practices.EnterpriseLibrary.Data.dll
   – Microsoft.Practices.EnterpriseLibrary.Data.SqlCe.dll

5. In the SmartClient.EnterpriseLibrary project, open SmartClientDatabase.cs file and replace the following using statement:

using Microsoft.Practices.SmartClient.EnterpriseLibrary.Data.SqlCe;

with:

using Microsoft.Practices.EnterpriseLibrary.Data.SqlCe;

Updating the Guidance Package

1. Open the GuidancePackage solution located at the SC-SF source folder.

2. Open the App.config.template located under the folders located at Templates\Solutions\Projects\Shell.*.* (Shell.Basic.CS, Shell.Basic.VB, Shell.Extended.CS and Shell.Extended.VB) in the SmartClientFactoryPackage project.

3. Find and replace on each App.config.template file the string “Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a” with “Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35”.

4. Create a folder to store the new assemblies (e.g. at %SC-SF installation folder%\Lib with EntLib 4.0). In this folder, copy the Enterprise Library 4.0 assemblies and the Smart Client assemblies generated in Step 1. You should have the same assemblies you have at %SC-SF installation folder%\Lib but updated to use Enterprise Library 4.0.

5. Open the file CreateSmartClientFactorySolutionCommon.xml file located at Recipes\Common folder of the SmartClientFactoryPackage project. You will change the path where the Create Solution recipe looks for the required assemblies by default.

6. Find the SupportLibrariesPath argument and replace it with the following:

7. Save all.

8. Register the custom Guidance Package. To do this, right click the SmartClientFactoryPackage project and select Register Guidance Package.

Update existing SCSF Application

1. If your solution uses the Microsoft.Practices.SmartClient.EnterpriseLibrary.dll assembly, follow the steps described in the Rebuilding the Block Assemblies section to update this assembly and perform the following sub-steps:

1. Find the Microsoft.Practices.SmartClient.EnterpriseLibrary.dll generated assembly located at %Source code installation folder%\Blocks\Offline\Source\DataAccess.EnterpriseLibrary\bin\Debug.
2. Copy the previous assembly and replace them in the Lib folder of your solution.
3. Update the references of your projects to use the updated Microsoft.Practices.SmartClient.EnterpriseLibrary.dll assembly
4. Remove the reference to Microsoft.Practices.SmartClient.EnterpriseLibrary.Data.SqlCe.dll (it was replaced with the one provided by Enterprise Library 4) and add a reference to Microsoft.Practices.EnterpriseLibrary.Data.SqlCe.dll assembly located at %Enterprise Library 4 installation folder%\Bin.

2. Copy the Enterprise Library 4.0 assemblies (located at %Enterprise Library 4 installation folder%\Bin) and replace them in the Lib folder of your solution.

3. Update the references to the Enterprise Library assemblies in all the projects in your solution using the new assemblies copied into the Lib folder.

4. Open the App.config file and find and replace the string “Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a” with “Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35”.

5. Save all

Bluetooth with C#

Punit Ganshani — Sat, 28 Jun 2008 18:25:18 +0000

Bluetooth Manager has following functionalities:

1. Discovery of devices

2. Finding out MAC address

3. Sending a File through Bluetooth

You can search the device, select one of the available ones and then send a text file to the user. The application uses In The Hand APIs. For more information about APIs: http://inthehand.com/

Click here to download the example

Regex: To match C#, Java, VB.Net Comments

Punit Ganshani — Tue, 29 Apr 2008 15:41:08 +0000

Ever worked on removing comments from a C#, Java, VB and VB.Net code?

Well, just adding 2 reg-ex to your library…

Click Regexlib.com to navigate to the actual page

C#/Java Matches: /* multi-line */ | // comment | /// XML Comment

VB/VB.Net Matches: REM comment | ‘comment | ”’ XML comment

Validation

Punit Ganshani — Wed, 23 Apr 2008 14:38:01 +0000

Let’s today understand Data Validation

The first principle: Assume no data to be valid.
Second principle : The rigidness of your rules will testify the validness of the data.

First, decide the parameters that you need to weigh your inputs on:

1. Range of Value
2. Value precision
3. Format
4. Length
5. Type

Third principle: Decide your strategy and follow it.

Now there are two philosophies in validating the data:
1. Negative test cases i.e. all those values for which validation test should fail.
2. Positive test cases i.e. all those values for which validation test should pass. (I recommend this )

Some key points to keep in mind:

1. Strong-data-typing: Numbers should be stored in Integer, Double, Float or a relevant data type rather than storing in a Generic data type. This besides validating the data, also enhances the performance (read memory allocation).

2. Not just client side validation: Validating at client side (using JavaScript/VbScript) is not just sufficient. Use appropriate server-side validations. However, this does not mean not validating at client side – it helps reducing server-side round trips.

3. Free-text Fields: Multiline fields (or free-text fields) should be checked before storing. They may contain some unwanted code like C# snippet, or a SQL query itself. Test it against SQL Injection. Also in ASP.NET applications, make sure that HTML inputs do not crash the application. An input like may do disasters. Prefer to HTML encode data before processing it.

1. In the page directive, add ValidateRequest = “false”
2. Encode using HtmlEncode
3. Use RegEx to remove Html Content

4. Upload/Download Paths: While making a Chat Engine (using WCF & WPF) that uses username/password and photograph of a user to log in, you may take path of the photograph placed on his machine. While someone wants to view it, it may not be accessible (since its on a network). Make sure a correct strategy is used and paths are validated before processing.

5. Special Characters in WebServices: WebServices do not allow special characters (like heart, diamonds) to be passed through the wire even when stored inside a string. Make sure that they are converted into Binary/Hex or other format before transmitting.

6. URLs: Urls/Cookies/QueryStrings should not be without encoding. Validation needs to be done for length, range, format and types.

Related posts:
Ajax – what not to do!

.NET 4.0 Unleashed

ASP.NET Best Practices

Only Numbers in TextBox

Punit Ganshani — Thu, 10 Apr 2008 16:06:11 +0000

Requirement: TextBox in C# should accept only numbers as input.

Solution:

Raise an event KeyPress and paste following line of code.

private void txtInput_KeyPress(object sender, KeyPressEventArgs e)
{
if (!Char.IsNumber(e.KeyChar))
e.Handled = true;
}

Here, e stands for the arguments of the function and e contains several attributes and methods like:

e.KeyChar : Character that has been pressed
e.Handled : Whether it is an acceptable character or not.

Related posts:
Interface vs Object vs Aspect Oriented Programming

VS 2008 : Plugin Pop-up issue

Using Smart Client with Enterprise Library 4