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Access an Object using a Variable

Posted on 2007-11-15
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Last Modified: 2010-04-15
Just starting out on C# from VB and I want to know since there is no Object Arrays in C# that can I access an object by using a String.

Non Working Example:
TheObject("Button4").visible=false

That is the kind of Functionality I am looking for.

Thanks
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Question by:scogger1974
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15 Comments
 
LVL 7

Expert Comment

by:dctuck
Comment Utility
If you're wanting to reference controls in the form you can use:
this.Controls["Button4"].Visible = false;
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Author Comment

by:scogger1974
Comment Utility
I guess the Second Part of this Question would come in ...
Could I also Name an Object Based on a string....
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Expert Comment

by:vbturbo
Comment Utility

string mystring = "somename";

this.Button1.Location = new System.Drawing.Point(632, 412);
this.Button1.Name = mystring;
this.Button1.Size = new System.Drawing.Size(75, 23);
this.Button1.TabIndex = 41;
this.Button1.Text = "Update db ";
this.Button1.UseVisualStyleBackColor = true;
this.Button1.Visible = false;
this.Controls.Add(this.Button1);
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Author Comment

by:scogger1974
Comment Utility
Here is the code based on what you said.  but here is whats happening
// Create Button
            Button ButtonA = new Button();
            ButtonA.Location = new Point(7, 146);
            ButtonA.Size = new Size(94, 23);
            ButtonA.Text = "ADD ITEM";
            groupBox4.Controls.Add(ButtonA);
            this.Controls["ButtonA"].Visible = false;

Here is the error it returns
Object reference not set to an instance of an object.
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Author Comment

by:scogger1974
Comment Utility
vbturbo:
  I know I can chage the Name but I want to be able to use that name to access the Object.
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Expert Comment

by:vbturbo
Comment Utility
       private void Form1_Load(object sender, EventArgs e)
        {
            Button ButtonA = new Button();
            ButtonA.Location = new Point(7, 146);
            ButtonA.Size = new Size(94, 23);
            ButtonA.Text = "ADD ITEM";
            //groupBox4.Controls.Add(ButtonA);
            this.Controls.Add(ButtonA);
        }

vbturbo
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LVL 18

Expert Comment

by:vbturbo
Comment Utility
sorry

        private void Form1_Load(object sender, EventArgs e)
        {
            Button ButtonA = new Button();
            ButtonA.Location = new Point(7, 146);
            ButtonA.Size = new Size(94, 23);
            ButtonA.Text = "ADD ITEM";
            this.groupBox1.Controls.Add(ButtonA);
            //this.Controls.Add(ButtonA);
        }
0
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LVL 18

Expert Comment

by:vbturbo
Comment Utility
and use for docking the button to always be inside the groupbox

ButtonA.Location = new Point(this.groupBox1.Top + 10, this.groupBox1.Left + 20);
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Author Comment

by:scogger1974
Comment Utility
If I set the .Name Property ... the Object name remains the same... I want to do something like this
although this doesnt work

Button "SomeString"= new Button();

and then be able to do

Object("Somestring").Visible = false;

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LVL 18

Expert Comment

by:vbturbo
Comment Utility
Im not quite sure what you mean

but here you create a button array object and add button objects, where you are able to set the properties of the buttons before adding them into the array

Button[] ButtonArray = new Button[9];

    public void AddButtons() {
        for (int x = 0; (x <= 9); x++) {
            ButtonArray[x] = new Button();
            ButtonArray[x] .Tag = x;
            ButtonArray[x].Text = ("Button " + x);
            ButtonArray[x].Size = new Size(60, 20);
            ButtonArray[x].Location = new Point(20, ((x * 20) + 4));
            ButtonArray[x].Parent = this;
            ButtonArray[x].Visible = true;
            .Click +=  new System.EventHandler(this.ButtonHandler);
           
        }
    }
   
private void Button2_Click(object sender, System.EventArgs e)
{
    MessageBox.Show("Button number " + ((Button)sender).Tag + " was clicked");
}

vbturbo
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Accepted Solution

by:
vbturbo earned 500 total points
Comment Utility
sorry minor conversion error

        public void AddButtons() {
            for(int x=0;x<9;x++)
   {
            ButtonArray[x] = new Button();
            ButtonArray[x] .Tag = x;
            ButtonArray[x].Text = ("Button " + x);
            ButtonArray[x].Size = new Size(60, 20);
            ButtonArray[x].Location = new Point(20, ((x * 20) + 4));
            ButtonArray[x].Parent = this;
            ButtonArray[x].Visible = true;
            this.ButtonArray[x].Click += new System.EventHandler(this.ButtonHandler);
           
        }
    }

        public void ButtonHandler(object sender, System.EventArgs e)
        {
            MessageBox.Show(("Button number "
                            + (((Button)(sender)).Tag + " was clicked")));
        }
0
 
LVL 1

Author Comment

by:scogger1974
Comment Utility
Exactly!!
I thought there was not the option to have an object Array in here but I guess I was wrong
Thanks..
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LVL 18

Expert Comment

by:vbturbo
Comment Utility
just glad it suited you, sorry for the many post's but im getting a bit rusty in c#
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LVL 1

Author Comment

by:scogger1974
Comment Utility
Its one thing to learn how to do something
but its another to learn how ask the right questions
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LVL 18

Expert Comment

by:vbturbo
Comment Utility
i suppose so -;)

thanks for the grade
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