Why isn’t point1 null? The answer is that Point is a value type, and theĭefault value for a Point is (0,0), not null. The following, usually unexpected result when checking if a variable isĬonsole.WriteLine(point1 = null) // False (huh?) This is called the default value for that type. Value, and even uninitialized variables of value types must have a Common C# Programming Mistake #2: Misunderstanding default values for uninitialized variables Sure that you’re dealing with the correct type of object to avoid C# programming problems. Parameter and have that method change the state of the object – make If you’re going to depend on some behavior which differs between valueĪnd reference types – such as the ability to pass an object as a method Security by the many similarities between C++ and C# keywords, thisīehavior likely comes as a surprise that may have you asking for help from a C# tutorial. Those with a C++ background, who were lulled into a false sense of Type, while the class keyword is used to define a reference type. The object type and pressing F12): public struct Point // defines a “reference” typeĪs shown above, in C# programming, the struct keyword is used to define a value The answer is to look at the definitions of the object types (which youĬan easily do in Visual Studio by placing your cursor over the name of But how can we know that without doing this experiment? We can therefore deduce that point1 and point2 each contain their own copy of a Point object, whereas pen1 and pen2 contain references to the same Pen object. For example: Point point1 = new Point(20, 30) Ĭonsole.WriteLine(point1.X) // 20 (does this surprise you?)Ĭonsole.WriteLine(pen1.Color) // Blue (or does this surprise you?)Īs you can see, both the Point and Pen objects were created the exact same way, but the value of point1 remained unchanged when a new X coordinate value was assigned to point2, whereas the value of pen1 was modified when a new color was assigned to pen2. Reference type, you could run into some surprises. If you don’t know whether the object you’re using is a value type or “gotcha” for those trying to learn C# programming. Instantiates the object and assigns it to a variable. Made by the programmer who wrote the object, not by the programmer who In C Sharp programming, however, that decision is Programmers of C++, and many other languages, are accustomed to being inĬontrol of whether the values they assign to variables are simply values Common C# Programming Mistake #1: Using a reference like a value or vice versa While most of the mistakes discussed in this article are C# specific, some are also relevant to other languages that target the CLR or make use of the Framework Class Library (FCL). This tutorial describes 10 of the most common C# programming mistakes made, or problems to be avoided, by C# programmers and provide them with help. However, a lot of C# coders unwittingly (or carelessly) throwĪway the benefits of this detection, which leads to some of the issuesĭiscussed in this C# tutorial. Place in languages which are more liberal with their enforcement of type This can save a lot of time in C Sharp programming, compared to tracking down the cause of puzzling errors which can occur long after the offending operation takes Their locations pinpointed quite accurately. Of typical C# programming errors being reported as early as possible, and The strict typeĬhecking in C#, both at compile and run times, results in the majority Of today’s CLR languages, C# is the most widely used forĬomplex, professional development projects that target the WindowsĬ# is an object oriented, strongly-typed language. Simplified model for component interaction, and debugging and profiling Languages that target the CLR benefit from features such asĬross-language integration and exception handling, enhanced security, a C# is one of several languages that target the Microsoft Common Language Runtime (CLR).
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