Is And As In C#

It has a simple hierarchy and quite easy to understand.Default access SpecifierPublic in C++ for Struct. Private for classesPrivate in C# .net.PlatformC++ is a language that runs on all sorts of platforms. (Range-based for loop in C++ is added since C++ 11)C# supports for each loop.Use of pointersYou can use pointers anywhere in the program.

Therefore, it is flexible language, but you may cause serious damage running OS.C# is highly protected. While I do feel that the article may be a bit biased its does present a lot of gotchas that new C# developers should keep and eye out for. Some of the mistakes listed are not C# exclusive and avoidable by simply educating ones self on how the language behaves (ex. value vs reference, types). Some solutions need to be prefaced with "depending on the case".

I also feel that the #9 may have missed the mark a little bit, they are there for catching errors IF one occurs and returning you to a "safe" place where you are able to safely recover. However, it is correct in saying that exceptions should not be used as a normal control statement. Even though I know better, I too, am guilty of using them incorrectly from time to time. The mistake would also benefit from having a bit more on how to use exceptions correctly.

LINQ like any language feature can be abused and used in such ways that it does make things harder to understand but it is a powerful tool that should not be overlooked. I like to use it when accessing data sources, and then prefer other control loops for any processing on the data. This separates processing code from data access visually and helps keep things easy to spot and understand. LINQ allows for the ability to create complex "SQL like" statements that MAY be more difficult to implement in the SQL flavor of choice.

LINQ vs Extension methods, it is key to keep your understanding of these clear. LINQ is not extension methods, LINQ is not Extension methods, LINQ is not extension methods. Extension methods allow for extending types that you don't necessarily have access to, such as third party dll's.

Linq is just really a syntactic sugar that allows for a different approach which may make things conceptually simpler to understand. For example, a few years ago Microsoft decided to add features to C# to make database access feel well integrated with the language. The resulting technology, Language Integrated Query , certainly supports that goal, but Microsoft achieved this without adding any direct support for data access to the language. Instead, Microsoft introduced a series of quite diverse-seeming capabilities. The last of these has an obvious connection to data access, but the rest are harder to relate to the task at hand. Nonetheless, these can be used collectively in a way that makes certain data access tasks significantly simpler.

But the features are all useful in their own right, so as well as supporting data access, they enable a much wider range of scenarios. Any operation performed on types sbyte, byte, short, or ushort return int values. To assign the result into the bitNot variable we had to use a cast, , operator, where Type is the type you wish to convert to (in this case – sbyte). The cast operator is shown as the Unary operator, x, in table 2-4.

Cast operators must be performed explicitly when you go from a larger type to a smaller type because of the potential for lost data. Generally speaking, assigning a smaller type to a larger type is no problem since the larger type has room to hold the entire value. Also, be aware of the dangers of casting between signed and unsigned types. You want to be sure to preserve the integrity of your data.

Many basic programming texts contain good descriptions of bit representations of variables and the dangers of explicit casting. While this simple example has just one, it's common to see a list of directives here. These state the namespaces of the types a source file intends to use. You will normally edit this list to match your file's requirements.

In this example, Visual Studio added using System; when I created the project. If you add a class representing a UI element, for example, Visual Studio would include various UI-related namespaces in the list. "I saw the LINQ statement first and I totally got what it was doing immediately" — it means you saw simple LINQ statements, in the cases where the decision to use LINQ was wise. "descriptors like very hard are highly subjective". You cannot step in/step over, which becomes problem e.g. if the LINQ contains non-MS extension methods — you can't just step in to find out what it does. You cannot use intermediate IDE window with statements that have lambdas.

Unlike imperative code, you can't review intermediate results as they're not kept in variables but lost in the call stack. Intermediate data is very often implicitly typed and unnamed. I saw a funny article entitled "What if Visual Studio had Achievements? The relevant item is #2 that says "Job Security – Written a LINQ query with over 30 lines of code".

In my previous comment, I was talking about _that_ kind of LINQ. While there certainly are advantages to using extension methods, they can cause problems and a cry for C# programming help for those developers who aren't aware of them or don't properly understand them. This is especially true when looking at code samples online, or at any other pre-written code.

A lot of time can be spent searching for a new version, or phantom "missing library", that doesn't exist. If you are writing libraries that you intend to share, you should target .NET Standard instead. In any case, the development tools will ensure that you only use APIs available in whichever version of .NET Standard you declare support for. Of course, languages do not exist in a vacuum—high-quality libraries with a broad range of features are essential. Some elegant and academically beautiful languages are glorious right up until you want to do something prosaic, such as talking to a database or determining where to store user settings. No matter how powerful a set of programming idioms a language offers, it also needs to provide full and convenient access to the underlying platform's services.

C# is on very strong ground here, thanks to its runtime, the class library, and extensive third-party library support. Another common reason to pass a variable by reference is to let the called method modify its value. Because this is allowed, C# always enforces specifying that a value is passed by reference even in the method call, something many other programming languages don't. This let developers reading the code easily spot places that can imply a type has had its value changed in a method, which is useful when analyzing the program flow. You've now seen the basic structure of C# programs. I created a solution containing two projects, one for tests and one for the program itself.

This was a simple example, so each project had only one source file of interest. Each began with using directives indicating which types the file uses. A namespace declaration stated the namespace that the file populates, and this contained a class containing one or more methods or other members, such as fields. The Mono project was launched in 2001, and did not originate from Microsoft.

That crucial move helped Mono find its niche, because it is now mainly used to create cross-platform mobile device applications in C#. It was open source from the start, and has been supported by a variety of companies over its existence. At the time of writing this, Mono is under the stewardship of a company called Xamarin, and has been since 2011.

Microsoft acquired Xamarin in 2016, and for now retains it as a distinct brand, positioning its Mono runtime as the way to run C# code on mobile devices. One illustration of this philosophy of generality was a language feature that was prototyped for C#, but which its designers ultimately chose not to go ahead with. The feature would have enabled you to write XML directly in your source code, embedding expressions to calculate values for certain bits of content at runtime. The prototype compiled this into code that generated the completed XML at runtime. Embedded XML expressions are a relatively narrow facility, only useful when you're creating XML documents. As for querying XML documents, C# supports this functionality through its general-purpose LINQ features, without needing any XML-specific language features.

XML's star has waned since this language concept was mooted, having been usurped in many cases by JSON . Had embedded XML made it into C#, it would by now feel like a slightly anachronistic curiosity. The language is actually a hybrid taken from C and C++. Comparable to Java, C# is an object-based language that is designed to help coders improve productivity when developing web applications.

These features make arriving at solutions to application and software issues faster and easier. C# continues its enforcement of type safety into runtime. This allows you to pinpoint many types of errors in C# much more quickly than in languages such as C++, where faulty type conversions can result in arbitrary values being assigned to an object's fields. However, once again, programmers can squander this great feature, leading to C# problems. They fall into this trap because C# provides two different ways of doing things, one which can throw an exception, and one which won't.

Some will shy away from the exception route, figuring that not having to write a try/catch block saves them some coding. The runtime part is called the Common Language Runtime because it supports not just C#, but any .NET language. Microsoft also offers Visual Basic, F#, and .NET extensions for C++, for example. The CLR environment employs a garbage collector, so you don't need to explicitly free the memory created for any object.

There's no equivalent of the C++ delete operator or the free() function in C . But that doesn't mean that you can just forget about all objects after you're done using them. Many types of objects encapsulate some other type of system resource (e.g., a disk file, database connection, network socket, etc.). Leaving these resources open can quickly deplete the total number of system resources, degrading performance and ultimately leading to program faults.

When compared with C++ templates, C# generics can provide enhanced safety, but also have somewhat limited capabilities. For example, it is not possible to call arithmetic operators on a C# generic type. Unlike C++ templates, .NET parameterized types are instantiated at runtime rather than by the compiler; hence they can be cross-language whereas C++ templates cannot. They support some features not supported directly by C++ templates such as type constraints on generic parameters by use of interfaces. On the other hand, C# does not support non-type generic parameters. Although classes and structures are similar in both the way they are declared and how they are used, there are some significant differences.

Classes are reference types and structs are value types. A structure is allocated on the stack when it is declared and the variable is bound to its address. Classes are different because the memory is allocated as objects on the heap. Variables are rather managed pointers on the stack which point to the objects. The is and as operators are two good ways of doing the cast of the objects, and they also help us to avoid exception in case of some failure during the cast.

"AS" keyword helps to do conversion from one type to other type. For instance in the below code we are converting object to a string data type. If the "AS" keyword is not able to type cast it returns NULL.

Executables typically have an .exe file extension in Windows, while libraries use .dll . Starting with .NET Core 3.0, it can generate a bootstrapping executable (with an .exe extension on Windows), but this just starts the runtime and then loads the .dll containing the main compiled output. In either case, the only difference between the main compiled output of an application and a library is that the former specifies an application entry point. Both file types can export features to be consumed by other components. These are both examples of assemblies, the subject of Chapter 12.

The static keyword is used to specify a static member, which means static members are common to all the objects and they do not tie to a specific object. This keyword can be used with classes, fields, methods, properties, operators, events, and constructors, but it cannot be used with indexers, destructors, or types other than classes. We also have explicit and implicit operators, meaning some operators require an explicit cast and some operators don't. LINQPad uses this technique to speed up the creation of new queries. A variation is to run a number of different algorithms in parallel that all solve the same task.

More bugs than a New York kitchen and slower than continental drift. If I wanted an environment hated and blocked by MSFT AAPL and GOOG equally I would definitely chose mono. You clearly don't like pointers (even if all C# classes are implemented as pointers to objects under the hood). No problem, many IT trainees are not good enough to handle pointers. Compared to Java of course, C# does not take much away from C++.

To make a soup analogy, the result is a mix of tomato soup, chocolate marshmallows, and clam chowder perfumed with skunk essence served in tin cans with proprietary locks. C++ is still the only way to write code once and easily run it across all the incompatible platforms out there. Like in C and C++ there are functions that group reusable code. The main difference is that functions, just like in Java, have to reside inside of a class. A method has a return value, a name and usually some parameters initialized when it is called with some arguments. It can either belong to an instance of a class or be a static member.

When you define nested namespaces, the convention is to create a matching folder hierarchy. If you create a project called MyApp, as you've seen, by default Visual Studio will put new classes in the MyApp namespace when you add them to the project. But if you create a new folder in the project called, say, Storage, Visual Studio will put any new classes you create in that folder into the MyApp.Storage namespace.

Again, you're not required to keep this—Visual Studio just adds a namespace declaration when creating the file, and you're free to change it. The compiler does not need the namespace to match your folder hierarchy. But since the convention is supported by Visual Studio, life will be easier if you follow it. Earlier, you saw that a project's References describe which libraries it uses.