Use value in a string as variable name

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1.00/5 (1 vote)

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Let say I have
string a = "hallo"
and have a combo-box with items "a", "b" and "c".

Let say that the selected item is "a"

Now my purpose is to use the value "a" (or "b" or "c") as variable name,
so some function GetVarFromString("a") returns "hallo".

Posted 12-Nov-13 8:39am

Member 10321326

Updated 12-Nov-13 9:27am

Kornfeld Eliyahu Peter

v3

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Maciej Los 12-Nov-13 16:58pm

Not enough information!
Please, be more specific and provide more details, for example about data binding.

3 solutions

Solution 4

Since FrameWork 1.1, the ComboBox Control exposes DisplayMember, and ValueMember, Properties which you can use with a DataSource to handle exactly the type of problem you describe here. MS has a complete example here:[^].

Another, simpler, technique you can use is to create a generic Dictionary of the form:

C#

private Dictionary<int,> dctComboXRef = new Dictionary<int,>
{
    {0, "hallo"},
    {1, "goodbye"},
    {2, "whatever"}
};

private void YourForm_Load(object sender, EventArgs e)
{
    foreach (var kvp in dctComboXRef)
    {
        comboBox1.Items.Add(kvp.Key);
    }
}

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    string selectedAsString = dctComboXRef[comboBox1.SelectedIndex];

    Console.WriteLine("selected " + selectedAsString);
}

Why did I use integers as the key in the Dictionary, rather than a string ? Because a ComboBoxItems collection is, by definition, a list which guarantees every Item has a unique index, and a Dictionary must have unique indexes, and because it's so simple to fetch the string from the Dictionary using the integer index of the Item selected.

The two techniques mentioned above are not the only ways (besides Reflection) you could handle the task of cross-referencing a string based on the selection in a ComboBox.

experiment + observe + analyze + study == competence :)

Posted 12-Nov-13 11:10am

BillWoodruff

Solution 1

I don't understand your problem, if you want variable a to have the same value of variable c then make a = c;

Posted 12-Nov-13 9:07am

Arnaldo P. Castaño

Comments

Member 10321326 12-Nov-13 15:30pm

This was a example not in my solution.

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Kornfeld Eliyahu Peter · Accepted Answer · 2013-11-12T09:26:00

There is a way to use string value as variable name, but it's a performance heavy, and I believe, that if yo use it you have a design problem in your code. So just before I show you the way to use string value as variable I ask you to consider using name-value pairs to get value according to key...

http://msdn.microsoft.com/en-us/library/5tbh8a42(v=vs.110).aspx[^]

Now let see it. The keyword is reflection. And reflection - for this purpose - can be used only on public fields of a class...

C#

public class ErrorMessages
{
    public string Msg1 = "Message 1";
    public string Msg2 = "Message 2";
    public string Msg3 = "Message 3";
}

ErrorMessages oErrorMessages = new ErrorMessages ( );

string szVal = Convert.ToString ( typeof ( ErrorMessages ).GetField ( "Msg3" ).GetValue ( oErrorMessages ) );

szVal will get 'Message 3' as value...