How to use Global Variables in C

Question

How do I declare a variable so that every class    cs  can access its content  without an instance reference

User · Answer

In C  you cannot define true global variables  in the sense that they don t belong to any class    This being said  the simplest approach that I know to mimic this feature consists in using a static class  as follows   public static class Globals       public const Int32 BUFFER SIZE   512     Unmodifiable     public static String FILE NAME    Output txt      Modifiable     public static readonly String CODE PREFIX    US-      Unmodifiable     You can then retrieve the defined values anywhere in your code  provided it s part of the same namespace    String code   Globals CODE PREFIX   value ToString      In order to deal with different namespaces  you can either    declare the Globals class without including it into a specific namespace  so that it will be placed in the global application namespace   insert the proper using directive for retrieving the variables from another namespace

User · Answer

First examine if you really need a global variable instead using it blatantly without consideration to your software architecture    Let s assuming it passes the test  Depending on usage  Globals can be hard to debug with race conditions and many other  bad things   it s best to approach them from an angle where you re prepared to handle such bad things  So     Wrap all such Global variables into a single static class  for manageability    Have Properties instead of fields   variables    This way you have some mechanisms to address any issues with concurrent writes to Globals in the future    The basic outline for such a class would be   public class Globals       private static bool  expired      public static bool Expired                get                          Reads are usually simple             return  expired                    set                          You can add logic here for race conditions                 or other measurements              expired   value                         Perhaps extend this to have Read-Modify-Write static methods        for data integrity during concurrency  Situational      Usage from other classes  within same namespace      Read bool areWeAlive   Globals Expired      Write    past deadline Globals Expired   true

User · Answer

There s no such thing as a global variable in C   Period   You can have static members if you want   public static class MyStaticValues      public static bool MyStaticBool  get set

User · Answer

A useful feature for this is using static  As others have said  you have to create a class for your globals   public static class Globals       public const float PI   3 14      But you can import it like this in order to no longer write the class name in front of its static properties   using static Globals        Console WriteLine  Pi is     PI

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