[c#] pass variable between functions

[heffer86]

I have two functions. How do I pass variables between the two?

    public void StudentBtt1_Click(object sender, EventArgs e)
    {
        _var1 = 5+5;
    }

    public void StudentBtt2_Click(object sender, EventArgs e)
    {
        Literal1.Text = _var1;
    }

[Gangsta]

Meaning access a variable in one from another function? that would be a scope trick. Use a variable declared outside...

if not, I have no idea what you're asking.

[heffer86]

  On 29/03/2010 at 05:54, Gangsta said:

Meaning access a variable in one from another function? that would be a scope trick. Use a variable declared outside...

if not, I have no idea what you're asking.

I have the variables declared outside of the functions, but I still can't access them. This is just a simple example what I am doing. What I do is click StudentBtt1 and update the variable to ten. Then with StudentBtt2 I want to show that updated variable. When I click StudentBtt2 I still get "1".

public int _var1 = 1;

    public void StudentBtt1_Click(object sender, EventArgs e)
    {
     //update to ten
        _var1 = 5+5;
    }

    public void StudentBtt2_Click(object sender, EventArgs e)
    {
        //show the updated variable
        Literal1.Text = _var1;
    }

[BGM]

you need to make the variable static, like..

static int x;   			

protected void Button1_Click(object sender, EventArgs e)
{
    x = x+5;
}

protected void Button2_Click(object sender, EventArgs e)
{
    Label1.Text = x.ToString();
}

however, the limitation with this is that is that a static variable is shared across all instances of the page and may will cause you issues if / when you have multiple users accessing the page.

a slightly better approach would be to use a session variable.. but global variables are not really 'supported' in c# and i think a best method would be to use a class

[Antaris Veteran]

Are you using WinForms/Desktop development, or ASP.NET?

It's quite important, as ASP.NET will require you to somehow persist your variables from one page view to the next, if that is what you need.

Your original solution would work perfectly fine for WinForms development, but not for ASP.NET, as when you view a page in ASP.NET the whole page class is instantiated, thus your variables would be instantiated as well.

Using a static instance as BGM suggested works for ASP.NET, again with the limitations he has expressed.

You could take advantage of either Session of ViewState too.

private int val;

protected void Page_Load(object sender, EventArgs e) {
    if (Session["myVal"] != null)
      val = (int)Session["myVal"];
}

public void StudentBtt1_Click(object sender, EventArgs e) {
  val = 5 + 5;
  Session["myVal"] = val;
}

public void StudentBtt2_Click(object sender, EventArgs e) {
  Literal1.Text = val.ToString();
}

private int val;

protected void Page_Load(object sender, EventArgs e) {
    if (ViewState["myVal"] != null)
      val = (int)ViewState["myVal"];
}

public void StudentBtt1_Click(object sender, EventArgs e) {
  val = 5 + 5;
  ViewState["myVal"] = val;
}

public void StudentBtt2_Click(object sender, EventArgs e) {
  Literal1.Text = val.ToString();
}

For this simple example, I'd recommend using ViewState.

Edited March 29, 2010 by Antaris
Reworded so I don't sound like a 'tard.

[+Majesticmerc MVC]

  On 29/03/2010 at 05:46, heffer86 said:

I have two functions. How do I pass variables between the two?

    public void StudentBtt1_Click(object sender, EventArgs e)
    {
        _var1 = 5+5;
    }

    public void StudentBtt2_Click(object sender, EventArgs e)
    {
        Literal1.Text = _var1;
    }

Assuming you're using ASP.NET, you could store the variable in the ViewState. For example:

    public void StudentBtt1_Click(object sender, EventArgs e)
    {
        _var1 = 5+5;
        ViewState["_var1"] = _var1;
    }

    public void StudentBtt2_Click(object sender, EventArgs e)
    {
        _var1 = ViewState["_var1"];
        Literal1.Text = _var1;
    }

This allows you to store the contents of "_var1" inside the actual content of the page, and retrieve it on when you click the second button. Do bear in mind that there is a performance cost associated with keeping things inside the ViewState, but in this case, the cost is negligible.

If this is all confusing, then it might be worth reading up on the ASP.NET Lifecycle, since how pages work can be quite strange for those that aren't familiar.

EDIT: Decryptor beat me to it :)

[Antaris Veteran]

He did? :p

[+Majesticmerc MVC]

  On 29/03/2010 at 07:54, Antaris said:

He did? :p

Its early, and its my day off :blush:

Sorry dude :p

[Antaris Veteran]

I know the feeling, but it's not my day off :(

[Mike]

  On 29/03/2010 at 07:32, Antaris said:

The solution heffer86 gave you ...

Take a look at the OP's name :p

[Antaris Veteran]

^ Rofl, I'm with Majesticmerc, it's too early :p

Edited :p