C - Winforms - Global Variables

Question

I want some variables to be global across the project and accessible in every form  How can I do this

User · Answer

If you re using Visual C   all you need to do is add a class in Program cs inheriting Form and change all the inherited class from Form to your class in every Form  cs     Program cs public class Forms   Form         Declare your global valuables here       Form1 cs public partial class Form1   Forms      Change from Form to Forms                 Of course  there might be a way to extending the class Form without modifying it  If that s the case  all you need to do is extending it  Since all the forms are inheriting it by default  so all the valuables declared in it will become global automatically  Good luck

User · Answer

You can use static class or Singleton pattern

User · Answer

yes you can by using static class  like this   static class Global       private static string  globalVar            public static string GlobalVar               get   return  globalVar            set    globalVar   value              and for using any where you can write   GlobalClass GlobalVar    any string value

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public static class MyGlobals     public static string Global1    Hello     public static string Global2    World      public class Foo        private void Method1                string example   MyGlobals Global1           etc

User · Answer

They have already answered how to use a global variable   I will tell you why the use of global variables is a bad idea as a result of this question carried out in stackoverflow in Spanish      Explicit translation of the text in Spanish    Impact of the change  The problem with global variables is that they create hidden dependencies  When it comes to large applications  you yourself do not know   remember   you are clear about the objects you have and their relationships   So  you can not have a clear notion of how many objects your global variable is using  And if you want to change something of the global variable  for example  the meaning of each of its possible values  or its type  How many classes or compilation units will that change affect  If the amount is small  it may be worth making the change  If the impact will be great  it may be worth looking for another solution   But what is the impact  Because a global variable can be used anywhere in the code  it can be very difficult to measure it   In addition  always try to have a variable with the shortest possible life time  so that the amount of code that makes use of that variable is the minimum possible  and thus better understand its purpose  and who modifies it   A global variable lasts for the duration of the program  and therefore  anyone can use the variable  either to read it  or even worse  to change its value  making it more difficult to know what value the variable will have at any given program point     Order of destruction  Another problem is the order of destruction  Variables are always destroyed in reverse order of their creation  whether they are local or global   static variables  an exception is the primitive types  int enums  etc   which are never destroyed if they are global   static until they end the program    The problem is that it is difficult to know the order of construction of the global  or static  variables  In principle  it is indeterminate   If all your global   static variables are in a single compilation unit  that is  you only have a  cpp   then the order of construction is the same as the writing one  that is  variables defined before  are built before    But if you have more than one  cpp each with its own global   static variables  the global construction order is indeterminate  Of course  the order in each compilation unit  each  cpp  in particular  is respected  if the global variableA is defined before B A will be built before B  but It is possible that between A andB variables of other  cpp are initialized  For example  if you have three units with the following global   static variables   Image1  In the executable it could be created in this order  or in any other order as long as the relative order is respected within each  cpp    Image2  Why is this important  Because if there are relations between different static global objects  for example  that some use others in their destructors  perhaps  in the destructor of a global variable  you use another global object from another compilation unit that turns out to be already destroyed   have been built later    Hidden dependencies and   test cases    I tried to find the source that I will use in this example  but I can not find it  anyway  it was to exemplify the use of singletons  although the example is applicable to global and static variables   Hidden dependencies also create new problems related to controlling the behavior of an object  if it depends on the state of a global variable   Imagine you have a payment system  and you want to test it to see how it works  since you need to make changes  and the code is from another person  or yours  but from a few years ago   You open a new main  and you call the corresponding function of your global object that provides a bank payment service with a card  and it turns out that you enter your data and they charge you  How  in a simple test  have I used a production version  How can I do a simple payment test   After asking other co-workers  it turns out that you have to  mark true   a global bool that indicates whether we are in test mode or not  before beginning the collection process  Your object that provides the payment service depends on another object that provides the mode of payment  and that dependency occurs in an invisible way for the programmer   In other words  the global variables  or singletones   make it impossible to pass to  test mode   since global variables can not be replaced by  testing  instances  unless you modify the code where said code is created or defined   global variable  but we assume that the tests are done without modifying the mother code    Solution  This is solved by means of what is called   dependency injection    which consists in passing as a parameter all the dependencies that an object needs in its constructor or in the corresponding method  In this way  the programmer    sees    what has to happen to him  since he has to write it in code  making the developers gain a lot of time   If there are too many global objects  and there are too many parameters in the functions that need them  you can always group your  global objects  into a class  style   factory    that builds and returns the instance of the  global object   simulated  that you want   passing the factory as a parameter to the objects that need the global object as dependence   If you pass to test mode  you can always create a testing factory  which returns different versions of the same objects   and pass it as a parameter without having to modify the target class   But is it always bad   Not necessarily  there may be good uses for global variables  For example  constant values    the PI value   Being a constant value  there is no risk of not knowing its value at a given point in the program by any type of modification from another module  In addition  constant values   tend to be primitive and are unlikely to change their definition   It is more convenient  in this case  to use global variables to avoid having to pass the variables as parameters  simplifying the signatures of the functions   Another can be non-intrusive  global  services  such as a logging class  saving what happens in a file  which is usually optional and configurable in a program  and therefore does not affect the application s nuclear behavior   or std    cout std    cin or std    cerr  which are also global objects   Any other thing  even if its life time coincides almost with that of the program  always pass it as a parameter  Even the variable could be global in a module  only in it without any other having access  but that  in any case  the dependencies are always present as parameters   Answer by  Peregring-lk

User · Answer

The consensus here is to put the global variables in a static class as static members  When you create a new Windows Forms application  it usually comes with a Program class  Program cs   which is a static class and serves as the main entry point of the application  It lives for the the whole lifetime of the app  so I think it is best to put the global variables there instead of creating a new one   static class Program       public static string globalString    This is a global string              lt summary gt          The main entry point for the application           lt  summary gt       STAThread      static void Main                 Application EnableVisualStyles            Application SetCompatibleTextRenderingDefault false           Application Run new Form1               And use it as such   public partial class Form1   Form       public Form1                 Program globalString    Accessible in Form1             InitializeComponent

User · Answer

Or you could put your globals in the app config

User · Answer

One way    Solution Explorer   Your Project   Properties   Settings Settings  Click on this file and add define your settings from the IDE   Access them by  Properties Settings Default MySetting    hello world

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