How to refer to a variable with a string format?

Question

A lot of times i want to automate some statements by using string formatting, but unfortunately it doesn't work !

for example if i have this code :

Textbox1.Text = "";
Textbox2.Text = "";
Textbox3.Text = "";

how can i achieve the same results by doing something like this :

for ( int i = 1; i < 4; ++i )
    string.Format( "Textbox{0}.Text", i ) = "";

the code above is completely wrong, my goal was to make the question clear .

Update : basically referring to a variable with a string

@stuartd : thanks for the reply, anything even if it's a console application — Focus, Mar 26 '15 at 20:54
Nobody seems to understand the question. All he wants is to refer to a variable with a string. That string could be built with string.Format. As far as I know, it's not possible. But I don't know everything. Maybe some shenanigans with reflection would make it possible. I don't know. — Pluc, Mar 26 '15 at 21:03
You've obfuscated for security too much - to tell us you want to mess with textboxes and then say it's a console application. Programming's all about automating - what do you want exactly and why can't you achieve it? — CindyH, Mar 26 '15 at 21:04
BTW, for strings the assignments could be chained: `Textbox1.Text = Textbox2.Text = Textbox3.Text = "Some string";`. But if you have quite a few controls to work with then I'd go with a `List<>` and call `ForEach` — Setsu, Mar 26 '15 at 21:05
You can access fields by using reflection, and check their names that way, but it would be awfully slow. — CindyH, Mar 26 '15 at 21:08
@CindyH - fields, but not variables. So reflection will not help OP according to "i want is to refer to a variable with a string" comment. — Alexei Levenkov, Mar 26 '15 at 21:10
If suggested duplicate not enough - this search http://www.bing.com/search?q=c%23+refer+to+variable+by+index will give you more options. — Alexei Levenkov, Mar 26 '15 at 21:16

score 1 · Answer 1 · answered Mar 26 '15 at 20:50

1

In asp.net, you can use the FindControl method of the parent control to these textboxes. Such as:

for ( int i = 1; i < 4; ++i )
    (Page.FindControl("Textbox" + i) as Textbox).Text = "";

answered Mar 26 '15 at 20:50

Tyler Day

1,690
12
12

great, what about if they were not textBoxes ? i mean something else not of type Control ! – Focus Mar 26 '15 at 20:55
Well everything in asp.net inherits from Control. If it's not a textbox then you can cast it to whatever you want. – Tyler Day Mar 26 '15 at 20:57
Is as operator better than a simple cast in this case? – D. Ben Knoble Mar 26 '15 at 20:59
2

Great solution. But when using the FindControl, remember that it's recursive - you have to start with the outermost control, then loop through all of its children, etc. If there's a textbox inside a panel, it won't be found when you just look at the controls on the window. But you can do great stuff with a recursive control formatter - I have in the past but no longer have access to the code. – CindyH Mar 26 '15 at 21:00
@CindyH - Yes, good to point this out. Usually I put my controls in a parent panel. Then I do Panel1.FindControl("txt1") etc. if you want to skip the recursive route. – Tyler Day Mar 26 '15 at 21:02
@Ben - "as" vs a cast would be about the same in this situation. "as" will return null if the cast operation fails, rather than raising an exception. – Tyler Day Mar 26 '15 at 21:05
Ok. I wasnt aware of the difference; thanks. – D. Ben Knoble Mar 26 '15 at 21:06
For WinForms, see [this answer](http://stackoverflow.com/a/4483962/1378739) – Setsu Mar 26 '15 at 21:09

ie. · Answer 2 · 2015-03-26T21:05:28.897

You can use dynamic:

    class Whatever { public string Text { get; set; } }
    class It { public string Text { get; set; } }
    class Can { public string Text { get; set; } }
    class Be { public string Text { get; set; } }

    static void Main()
    {
        var whatever = new Whatever();
        var it = new It();
        var can = new Can();
        var be = new Be();

        foreach (var item in new dynamic[] {whatever, it, can, be})
            item.Text = item.ToString();
    }

But you should enumerate processing items in any case and know property/method names in the compile time. Otherwise, go ahead and use reflection.

How to refer to a variable with a string format?

2 Answers2