Genericize access to variables

[Ennis Ray Lynch Jr]

Yes, however, you may not like it.

foreach(Control control in Controls){
if(control is Label){
((Label)control).Text = "Something";
}
}

Unfortunately this will set all labels. If you are in Windows forms you can use the Tag option to set a tag, or you can subclass your Label control to give it a type. The other option is, after Initialize component, place all Labels you care about looping through in a collection.

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[Chris Trelawny Ross]

Here's a refinement that will only touch all labels you care about:

foreach (Control control in Controls)
{
if (control is Label && label.Name.StartsWith("labelNamePrefixToModifyAsAGroup"))
{
((Label)control).Text = "Something";
}
}

[Lost User]

Hax..

[Luc Pattyn]

which can be reduced to

foreach (Control c in Controls) if (c.Name.StartsWith("labela")) c.Text = "Something";

as every Control has a Name and a Text property. :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles] Nil Volentibus Arduum

Please use <PRE> tags for code snippets, they preserve indentation, and improve readability.

[Chris Trelawny Ross]

Slaps self on head for missing that one. :doh:

[realJSOP]

Reference parameters are your friend:

private void SetLabelText(ref Label label, string text)
{
label.Text = text;
}

private void SomeFunction()
{
SetLabelText(ref label1, "something1");
SetLabelText(ref label2, "something2");
SetLabelText(ref label3, "something3");
}

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-----
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[Ian Shlasko]

No need for 'ref', unless you want to change what the label1, label2, and label3 variables point to.

Proud to have finally moved to the A-Ark. Which one are you in?
Author of the Guardians Saga (Sci-Fi/Fantasy novels)

[The Man from U N C L E]

for (int i=1;1<4;i++){
this.Controls[string.Concat("labela", i.ToString())].Text = "something";
}

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[Lost User]

No-one with a LINQ version yet?

class Form1
{
IEnumerable<Control> summingLabels;

public Form1()
{
InitializeComponent();

summingLabels =
	from c in Controls.Cast().AsQueryable()
	where c.Name.StartsWith("sumLabel")
	select c;

// later on, when you need them
foreach(Control l in summingLabels)
	l.Text = l.Name;
}

}

Keep a pointer around to the controls that you found; no need to iterate them every time :)

I are Troll :suss:

[Daniel Grunwald]

The correct answer is: don't do that If you need multiple storage locations (variables) and access them by index, use an array. If you really have multiple variables (e.g. because they are generated by the VS forms designer), then you can still put those into an array:

Label[] labels = { labela1, labela2, labela3 };

[PIEBALDconsult]

Hear hear!

[Paul Michalik]

David Knechtges wrote:

Is there a way to do that?

No, at least if I understand what you want... However, why would you want to do that? What's wrong with:

Label[] labela = {
labela0,
labela1,
labela2,
labela3,
};
//...
for (int i=0;i<4;i++)
labela[i].Text = "something";

modified on Wednesday, September 1, 2010 5:55 PM

[AspDotNetDev]

This answer was already posted hours ago.

[Forum Guidelines]

[Lukasz Nowakowski]

You can also try reflection if you really really really really really really really really must do it this way and not using array/collection (depending on a situation).

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[Alexander Voronin]

Try to use this construction:

this.GetType().GetField("variablename")

This should work for c# but better try to avoid such kind of code. Other languages has different RTTI, for example in c/c++ this is impossible at all.

[ExportedNorwegian]

Not sure about the performance implications of FindControl.. But this one is pretty close to what you originally wrote

for (int i=1;i<4;i++)
(Controls.FindControl("labela" + i.ToString()) as Label).Text = "something";

[BC3Tech]

how about lambda? :)

foreach (Control l in Controls.Cast().Where(c => c.Name.StartsWith("sumLabel")))
l.Text = l.Name;

[Dave Buhl]

This is not exactly what you were asking for but is an alternative using binding. This may be overkill for what you are trying to do but it would be more elegant. Bind your labels as you create them to an object of a class that implements INotifyChanged then when you change the property of the object each label will be updated without having to work loops. http://stackoverflow.com/questions/639894[^] Dave

[JaceTheAce]

Array.ForEach(new Control[] { labela1, labela2, labela3 }, delegate(Control c) { c.Text = "something"; });

[Lost User]

Lambda's look cool :cool: It's either searching through the collection and keeping the result around, or hardcoding them in advance. Attributes that mark a set of fields as a group might be another option, but that would add a bit more complexity. No, I think I like the lambda better. Would also be cool combined with a regex :) Nearly forgot, but that cast in my original query would be redundant, as we'd only need to store labels;

class Form1
{
IEnumerable summingLabels;
public Form1()
{
InitializeComponent();

	summingLabels =
		from c in Controls.Cast().AsQueryable()
		where c.GetType() == typeof(Label)
		&& c.Name.StartsWith("label")
		select c as Label;

	// later on, when you need them
	foreach(Label l in summingLabels)
		l.Text = l.Location.ToString();
}

}

I are Troll :suss: