Global varible

[Jim McGivney]

I am a C# newbie.
I believe I need a Global variable or shared variable or universal variable,
but do not know how to create it.
As an example. I have a function that places a circle on a picturebox when
a button is pushed. I would like to change the position of the circle with
each button push, but do not know how to create a global variable to store
the last position of the circle.
As a work around I store the value in a textbox.
How do I create a variable that can be shared between functions and whose
scope is not ended when the function has ended?
This must be easy, but I can't figure it out.
Thanks,
Jim

 

[Jon Skeet [C# MVP]]

I am a C# newbie.
I believe I need a Global variable or shared variable or universal variable,
but do not know how to create it.
As an example. I have a function that places a circle on a picturebox when
a button is pushed. I would like to change the position of the circle with
each button push, but do not know how to create a global variable to store
the last position of the circle.

You don't need a global variable for that. You need an instance
variable.

As a work around I store the value in a textbox.
How do I create a variable that can be shared between functions and whose
scope is not ended when the function has ended?
This must be easy, but I can't figure it out.

Just declare it as an instance variable, the same as any other. If you
don't know about instance variables, I suggest getting a book or C#
tutorial. I know this *sounds* rude, and I don't *want* to be rude, but
newsgroups aren't the best place to learn a language from the basics -
they're better for specific questions.

The good news is that there are plenty of C# tutorials available for
free on the net.

 

[Mark Broadbent]

You need to seriously question your design. With OOP, global vars should be
absolutely kept to a minimum because they should not be necessary in 99.9%
of the time.
If you need to access an item across classes then expose the item via a
public property.
For the record, Global variables can be achieved using public static
variables.

The fact that you have asked this question leads me to think that you should
spend a little time in the C# /OOP books and read the language and OOP
essentials (and more) before attempting to implement something, otherwise
you are heading down a slippery path to a bad program and programming.

BTW it just sounds like you need to use a private class level variable to
store the circle position. This would then be available to all functions
within the class instance.

Br,

Mark.

 

[Mark Broadbent]

Just a follow-up from my original post, and to add to Jon's; getting a good
book and reading from page 1 to the end and re-reading is really the best
way to get started. Its really one of the best ways that you could find out
about information and practices that you would probably not come across
otherwise. It also helps you realise other topics and books you need to
read.
My .Net library just seems to get bigger and bigger -the subject (including
OOP) is just huge, but the thirst for knowledge is too.

A few books for you...
1. A programmer's Introduction to C# by Eric Gunnerson (I've got the Second
Edition but there might be a newer edition now). It's very informative and
Eric is a big player to C# and .NET at microsoft.
2. C# A complete reference by Herbert Schildt. I just loved this book, it
was my bible to learning C# and I still go back to it to this day. Some
people don't like this book, but for me it answered nearly all my initial
questions and got me on my way to where I am now.
3. An Introduction to Object-Orientated Programming 3rd Edition by Timothy
Budd. You will probably find this book a little to advanced to start with,
but once you are ready for it, it is unsurpassed in my opinion. It discusses
many different OOP questions (using multi language examples) which I am
constantly wondering about and questioning myself. It is simply brilliant.

Also check out Jon's website, he has got a nice set of FAQ's, examples and
is imo one of the best ng posters here. Stay with the ng and keep an eye out
for questions that might interest you -and mark and read the thread. It is
great way to pick up things.

Br,

Mark.

 

[A C# programmer]

I use global variable as following:

//Global.cs
namespace my_name
{
public class G
{
public static int g_var;
...
public G() { }
}
}

//other.cs
namespace my_name
{
public class my_class
{
G.g_var = 5;
...
Console.WriteLine(G.g_var.ToString());
...
}
}

I don't know if this answer your question. Good luck!


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