C# Global Variable ExamplesUse a global variable, implemented as public static property. Store globals in a static class.
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Global variables. These are useful. But they can lead to problems that are hard to debug. Global variables can cause errors in software development.
Many programs can benefit from global variables if used in a controlled manner. We use the static keyword. A separate static class can also be used.
Static, Singleton
An example. The static keyword describes something that is part of a type, not an instance of the type. This word was chosen for historical reasons—it was used in C and C++.
Next We see 2 files: one that contains the global variables in a static class, and Program.cs, which uses the global class.
Const GlobalString is a public global variable. You must assign its value inline with its declaration at the class declaration space.
Property GlobalValue is a public static property with get and set accessors. This is an access routine of a backing store.
Field A global field could cause problems in your program because it does not use an access routine.
Global variables class, GlobalVar.cs: C#
/// <summary> /// Contains global variables for project. /// </summary> public static class GlobalVar { /// <summary> /// Global variable that is constant. /// </summary> public const string GlobalString = "Important Text"; /// <summary> /// Static value protected by access routine. /// </summary> static int _globalValue; /// <summary> /// Access routine for global variable. /// </summary> public static int GlobalValue { get { return _globalValue; } set { _globalValue = value; } } /// <summary> /// Global static field. /// </summary> public static bool GlobalBoolean; }
C# program that uses global variables, Program.cs
using System; class Program { static void Main() { // Write global constant string. Console.WriteLine(GlobalVar.GlobalString); // Set global integer. GlobalVar.GlobalValue = 400; // Set global boolean. GlobalVar.GlobalBoolean = true; // Write the 2 previous values. Console.WriteLine(GlobalVar.GlobalValue); Console.WriteLine(GlobalVar.GlobalBoolean); } }
Important Text 400 True
Access routines. Global variables are used most effectively when accessed through special methods called access routines. You can use access routines in nearly any programming language.
Tip These methods provide another layer of abstraction over how you use the global variables.
Threads. Static fields can introduce problems when using multithreading, which is used extensively in websites. An access routine could provide locking using the lock-statement.
Also This is a problem in many Windows Forms applications that use BackgroundWorker threads.
A summary. We used global variables by adding a static class with constants, properties and public fields. You can also define methods with parameters to access the static variables.
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