C# interview questions and answers
- What debugging tools come with the .NET SDK? CorDBG – command-line debugger, and DbgCLR – graphic debugger. Visual Studio .NET uses the DbgCLR. To use CorDbg, you must compile the original C# file using the /debug switch.
- What does the This window show in the debugger? It points to the object that’s pointed to by this reference. Object’s instance data is shown.
- What does assert() do? In debug compilation, assert takes in a Boolean condition as a parameter, and shows the error dialog if the condition is false. The program proceeds without any interruption if the condition is true.
- What’s the difference between the Debug class and Trace class? Documentation looks the same. Use Debug class for debug builds, use Trace class for both debug and release builds.
- Why are there five tracing levels in System.Diagnostics.TraceSwitcher? The tracing dumps can be quite verbose and for some applications that are constantly running you run the risk of overloading the machine and the hard drive there. Five levels range from None to Verbose, allowing to fine-tune the tracing activities.
- Where is the output of TextWriterTraceListener redirected? To the Console or a text file depending on the parameter passed to the constructor.
- How do you debug an ASP.NET Web application? Attach the aspnet_wp.exe process to the DbgClr debugger.
- What are three test cases you should go through in unit testing? Positive test cases (correct data, correct output), negative test cases (broken or missing data, proper handling), exception test cases (exceptions are thrown and caught properly).
- Can you change the value of a variable while debugging a C# application? Yes, if you are debugging via Visual Studio.NET, just go to Immediate window.
- Explain the three services model (three-tier application). Presentation (UI), business (logic and underlying code) and data (from storage or other sources).
ADO.NET Entity Framework
The ADO.NET Entity Framework is an ORM (Object Relational Mapping) tool and is Microsoft’s main data access strategy moving forward. Microsoft released version 1 with Visual Studio 2008 SP1 with the .NET Framework 3.5 SP1. They released version 4 with Visual Studio 2010 and the .NET Framework version 4. The product team decided to sync the version number with the version of the .NET Framework. You may see references to v1 as Entity Framework v3.5 as well as v1 to reflect this.
ORM tools allow you to work with your relational database in a way that makes more sense to you as a developer and doesn’t require you to hand code SQL (which is something I don’t think many developers ever actually want to do on a regular basis). You work with a set of objects in your application that represent the database and an ORM tool will generate dynamic SQL that is sent to the database and executed. I have heard it said that ORM tools have an 80/20 use ratio, meaning that on average an ORM tool will solve 80% of your database access issues and the other 20% will likely need to be done with stored procedures or some other method. I think this is a solid ratio, but the ratio tends to be more like 95/5 for me. The real ratio will ultimately depend on the type of applications that you write. For quite a few of the projects I work on, the Entity Framework solves 100% of my data access problems. On average, I would say that just by using an ORM, my data access development time is cut by at least 75%. Since the ORM tool handles all of my CRUD (Create Read Update Delete) operations, I don’t have to write and debug SQL code for basic data access. This is, of course, the beauty of ORM in general and the Entity Framework fills this space nicely.
How to save data from dataset?
The modified data needs to be sent back to the database in order to save it. Therefore, to send the modified data to a database, the Update method of a TableAdapter or data adapter needs to be called. The Update method executes either of INSERT, UPDATE, or DELETE depending on the RowState in the table.
In Visual Studio a TableAdapterManager component is used for saving the proper order based on the foreign-key constraints of the database.
Although the procedure to save the data may change depending upon the applications, the following steps throw light on the generalized concept:
The code sends updates to the database should be written within a try/catch block.
The data row should be located to determine the problem area and the code should then be reattempted.
ASP.NET 2.0 Interview Questions
1. What is the name of the property of ASP.NET page that you can query to determine that a ASP.NET page is being requested not data being submitted to web server? A. FirstGet B. Initialized C. IncludesData D. IsPostBack
IsPostBack
2. While creating a Web site with the help of Visual Studio 2005 on a remote computer that does not have Front Page Server Extensions installed, which Web site type will you create in Visual Studio 2005? A. Remote HTTP B. File C. FTP D. Local HTTP
Hypertext Transfer Protocol (HTTP)
3. If you want to create a new Web site with the help of Visual Studio 2005 on a Web server that is hosted by your ISP (Internet Services provider) and the Web server has Front Page Server Extensions installed, what type of Web site type would you create in Visual Studio 2005? A. Local HTTP B. File C. FTP D. Remote HTTP
Hypertext Transfer Protocol (HTTP)
4. For separating server-side code from client-side code on a ASP.NET page, what programming model should you use? A. Separation model B. Code-Behind model C. In-Line model D. ClientServer model
5. Amit created a new Web site using Visual Studio 2005 in programming language C#. Later, Amit received an existing Web page from his boss, which consisted of the Contact.aspx file with the Contact.aspx.vb code-behind page. What must Amit do to use these files? A. Amit can simply add the files Contact.aspx, Contact.aspx.vb into the existing Web site, because ASP.NET 2.0 supports Web sites that have Web pages that were programmed with different languages. B. The Contact.aspx file will work, but Amit must rewrite the code-behind page using C#. C. Both files Contact.aspx and Contact.aspx.vb must be rewritten in C#. D. Amit must create a new Web site that contains these files Contact.aspx and Contact.aspx.vb. Set a Web reference to the new site.
6. If you want to make a configuration setting change in your server that will affect to all Web and Windows applications on the current machine. Where you will make the changes? A. Global.asax B. Web.config C. Machine.config D. Global.asax
7. If you want to make a configuration setting change that will affect only the current Web application. Which file will you change? A. Web.config that is in the same folder as the Machine.config file B. Web.config in the root of the Web application C. Machine.config D. Global.asax
8. For making a configuration setting change that will affect only the current Web application. Is there any tool that has a user-friendly Graphical User Interface (GUI)? A. The Microsoft Management Utility B. Microsoft Word C. Visual Studio, using the Tools > Options path D. Web Site Administration Tool
