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C# Increment for loop every time button is pressed

I googled a few things before posting, but I couldn't find anything like this. Basically, I want to take text from a textbox, save as a variable (say history1) to then be able to call that in the future to display the text. I can do that, but what I'm stuck with is that I want 3 variables (history1, history2 and history3, for example) and each time the button is pressed the string is moved to the next variable.
For example, the button is pressed, the text is saved as variable history1. The text is changed and the button is pressed again, the text from history1 is moved to variable history2, and the new text is saved as history1. This would only need to work for 3 instances though, not infinitely, so when text is stored in history3 and the button is pressed the text is just overwritten.
The way I had thought of approaching this was:
string history1;
string history2;
string history3;
for (int i = 1; i < 4; i++)
{
history1 = txtOutput.Text;
btnToFile_Click()
{
history2=history1;
btnToFile_Click()
{
history3=history2;
}
}
}
However, this isn't going to work because the btnToFile_Click doesn't take any arguements. Is there an easier way to go about this or just a way to fix the method not taking arguements ?
Thanks in advance!

Make sure that you delcare history1, history2, and history3 on the form level (not inside any method).
Then, have the following code inside the handler of the click event of the button:
history3 = history2;
history2 = history1;
history1 = txtOutput.Text;

You don't need to call the btnToFile_Click() method multiple times in your loop, just move the text from end textbox to another in reverse order. Nor do you need a loop because you only have three textboxes.
Why reverse order? So you move the value to the next textbox before it is overwritten by the new value.
So:
history3 = history2;
history2 = history1;
history1 = txtOutput.Text;

btnToFile_Click() is a Click event handler for btnToFile (a button). You're not supposed to call that method yourself, it's called by the UI framework (say WPF or WinForms etc.). By the way, it does receive a parameter, then event source (since you can assign the same event handler to multiple buttons and do something based on which one sent the event)

You can try saving in a string array and move the strings within it when you call the button clicked event

Is there a way to append output to a text field without taking focus?

I'm trying to add text to a RichTextBox using the AppendText method, and would like to find a way to Not take focus of the text box in this motion - reason being that I have an event response to the text box getting focus, that causes a conflict in my overall scheme...
Again, the question here is effectively; How can I use the AppendText method without triggering focus on a rich text box.
As I'm typing this I've almost decided that I can remove my event response method before the append and add it in again after; but if anyone has a better suggestion I'm all ears.
Thanks. And if I can submit any code to spur suggestions I'm open to it; I just assume that most anyone using this site can visualize what I'm portraying.

You can use a boolean variable to determine if it was you who fired the event (or the user)
bool firedByUser ;
When calling the AppendText method do something like this
firedByUser = false ;
rtb.AppendText("sample") ;
firedByUser = true ;
And in the method that you are handling the Focus on the RichTextBox
if(firedByUser)
{
//keep doing what you are doing now
}

Second TextBox showing same Text Selection as first

Long time listener, first time caller here. I'm having a strange issue with the TextBox in WinRT C#/XAML that I hope someone may be able to help me with.
Basically, I'm working on creating a Custom Control that essentially requires a second TextBox to be a copy of the first, including showing the same Text, and showing the same Selected Text. Obviously for the Text requirement I simply respond to the TextChanged event on the first TextBox and set the Text of the second TextBox to the Text from the first, which works great.
For the Selected Text requirement I started with a similar solution, and my code for this is as follows:
void TextBox1_SelectionChanged(object sender, RoutedEventArgs e)
{
this.TextBox2.Select(this.TextBox1.SelectionStart, this.TextBox1.SelectionLength);
}
This seemed to work pretty well when initially used with a mouse:
But I'm having a problem when selecting text with Touch. I double-tap within the TextBox to create the first "anchor" as you do in Touch, then drag to begin the selection; but I only ever manage to select a single character normally before the selection stops. The TextBox doesn't lose focus exactly, but the behaviour is similar to that; the selection anchors disappear and I can't continue selecting anything unless I re-double-tap to start a new selection. If I remove the code to select text in TextBox2 then the Touch selection behaves perfectly in TextBox1.
I've been trying to fix this for a while and cannot, I'm not sure if I can get the desired behaviour with WinRT TextBoxes. Does anyone have any ideas? Or perhaps another way to implement a solution with two TextBoxes with this behaviour?
Thanks a lot.

So this is far from an answer, but discovered a few things that maybe will help you or others come up with a potential workaround. Apologies if these are things you've already seen and noted.
First, it's not the call to TextBox2.Select() that's the problem per se. This for instance, works fine for me
private void txt1_SelectionChanged(object sender, RoutedEventArgs e)
{
var start = TextBox1.SelectionStart;
var length = TextBox1.SelectionLength;
TextBox2.Select(3, 5);
}
unfortunately, using start and length versus the hard-coded 3 and 5, that is, the following, DOES NOT WORK:
private void txt1_SelectionChanged(object sender, RoutedEventArgs e)
{
var start = TextBox1.SelectionStart;
var length = TextBox1.SelectionLength;
TextBox2.Select(start, length);
}
I also discovered that I could select TWO characters if I started from the end, but only one from the beginning. That got me to thinking about dispatching the call to set the second selection:
private void txt1_SelectionChanged(object sender, RoutedEventArgs e)
{
var start = TextBox1.SelectionStart;
var length = TextBox1.SelectionLength;
Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Low,
() => TextBox2.Select(start, length));
}
Now I can select 2 from the front and 3 and sometimes 4 from the back. Took it a step further, and was able to select as many as six or seven with a really fast swipe.
private void txt1_SelectionChanged(object sender, RoutedEventArgs e)
{
var start = TextBox1.SelectionStart;
var length = TextBox1.SelectionLength;
Dispatcher.RunIdleAsync((v) => Highlight());
}
public void Highlight()
{
TextBox2.Select(TextBox1.SelectionStart, TextBox1.SelectionLength);
}
Seems like the trick to working around this is not setting TextBox2 until whatever vestiges of the TextBox1 SelectionChanged event have completed.
This may be worth registering on Connect.

Mine is only a partial solution as well.
I did some debugging and noticed that the SelectionChanged event is fired throughout the text selection process. In other words, a single finger "swipe" will generate multiple SelectionChanged events.
As you found out, calling TextBox.Select during a text selection gesture affects the gesture itself. Windows seems to stop the gesture after the programmatic text selection.
My workaround is to delay as long as possible calling the TextBox.Select method. This does work well, except for one edge case. Where this method fails is in the following scenario:
The user begins a select gesture, say selecting x characters. The user, without taking their finger off the screen, pauses for a second or two. The user then attempts to select more characters.
My solution does not handle the last bit in the above paragraph. The touch selection after the pause does not actually select anything because my code will have called the TextBox.Select method.
Here is the actual code. As I mentioned above, there are multiple selection changed events fired during a single selection gesture. My code uses a timer along with a counter to only do the programmatic selection when there are no longer any pending touch generated selection changed events.
int _selectCounter = 0;
const int SELECT_TIMER_LENGTH = 500;
async private void TextBox1_SelectionChanged(object sender, RoutedEventArgs e)
{
// _selectCounter is the number of selection changed events that have fired.
// If you are really paranoid, you will want to make sure that if
// _selectCounter reaches MAX_INT, that you reset it to zero.
int mySelectCount = ++_selectCounter;
// start the timer and wait for it to finish
await Task.Delay(SELECT_TIMER_LENGTH);
// If equal (mySelectCount == _selectCounter),
// this means that NO select change events have fired
// during the delay call above. We only do the
// programmatic selection when this is the case.
// Feel free to adjust SELECT_TIMER_LENGTH to suit your needs.
if (mySelectCount == _selectCounter)
{
this.TextBox2.Select(this.TextBox1.SelectionStart, this.TextBox1.SelectionLength);
}
}

C# breaking out of a loop from separate class/method

I have a block of code that repeats using a "for" loop, and each loop constructs a form to display some text. Some thing like the shorthand code below.
Main()
{
For (int x: x<=20; x++)
{
createform(string[x]);
}
}
So for each loop a different string is passed to a method that will construct a form as below.
createform void (string input_)
{
...
code to build form and add a button "cancelbutton"
form.text = intput_
....
form.cancelbutton.Click += // and I want this to cause the original loop to end....
}
No I know I could use the button to make int x greater than 20 and that would end the loop, but I don't actually know what the max value will be as this is dynamic. Again I could work this out and do he same thing but it seems a bit "messy".
Is there a neater way to cause the button click to exit the loop. How about if the Createform method is in a separate class to main, does that make any difference?

If your loop runs from 0 to 20 (or even over 9000) the user won't be able to click the cancel button in time. In fact, since it is all on one thread, the loop will finish before the UI responds to the click, but maybe I have misunderstood. Could you just have a boolean flag which you check each time you enter the loop and set it to false once the user clicks the button?

Just add a variable and code the click event:
static bool clicked;
Main()
{
clicked = false;
For (int x: (x<=20) && !clicked; x++)
{
createform(string[x]);
}
}
public static void Click_Detector(object sender, EventArgs e) {
clicked = true;
}
Your routine would need to do something like this:
createform void (string input_)
{
...
code to build form and add a button "cancelbutton"
form.text = intput_
....
form.cancelbutton.Click += MainClass.Click_Detector;
}

You shouldn't be using a loop to create each form. Assuming you have a submit button. Every time the user clicks submit, you should explicitly show the next form. That way, if a user clicks cancel, you don't have to worry about the rest of the forms.

The first solution that comes to my mind is: return value of the method True/False and in foreach check for its return value, if False=> break.

Your psuedo code isn't indicating how you are showing the form in CreateForm(). Is this going to be a modal or non modal? It would have to be modal, otherwise, you'd just keep creating forms until the cows come home. Remember, adding a handler to the click button doesn't actually execute the handler method until the click button is clicked.
Presumably your click event handler could set the value of x to be greater than 20, but since you said you're not sure what the maximum is, you could have a do loop governed by a boolean flag, and your createform() could set the state of the flag.
I'd recommend rethinking your problem space, as this overall approach seems really convoluted. I don't understand your UI, but it seems like your intent is to have the user control the exit of an infinite loop, like those old RPGs that ask you "Do you want to go on an adventure Yes/No", and it would continue asking you until you hit "Yes". These are pointless and confusing.

Add a boolean to the class and have the click event set the boolean value. Then you can break from the loop. However, if your real world use is the question above I would agree with the answer given by mikerobi.

One good solution would be to use the CancelAsync() method of the BackgroundWorker class: http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.cancelasync.aspx
If you don't want to work with a separate thread to improve the performance, that I don't recommend, is to set a class level boolean value when the button clicked, then the for loop checks that boolean value in each next process.

How to detect previous state of text field in C#?

I'm coding a simple text editor using Windows Forms. As in many editors, when the text changes the title bar displays an asterisk next to the title, showing that there is unsaved work. When the user saves, this goes away.
However, there is a problem. This is handled in the change event of the main text box. But this gets called too when a file is opened or the user selects "New file", so that if you open the editor and then open a file, the program says that there are unsaved changes. What is a possible solution?
I thought of having a global variable that says whether the text changed in a way that shouldn't trigger the asterisk, but there has to be a better way.

before loading data to a textbox, unassociate first the eventhandler for change
uxName.TextChanged -= uxName_TextChanged;
uxName.Text = File.ReadAllText("something.txt");
uxName.TextChanged += uxName_TextChanged;

This is a horrible solution, but every time the text change event fires, compare the value of the textbox to some variable, and if they are different store the contents on the textbox in a variable and add the asterisk. When the method is invoked via the New File dialog or any other such event that is NOT changing the text, the asterisk won't appear.
This is not a viable solution for a real text editor since the memory would quickly get out of hand on even medium-sized files. Using a finger tree or whatever data structure text editors use to compare "versions" of the text is the only real efficient solution, but the premise is the same.
http://scienceblogs.com/goodmath/2009/05/finally_finger_trees.php
Below the second picture he mentions the use of finger trees in text editors to implement an extremely cheap "undo" feature, but I'm sure you can see the validity of the tree for your problem as well.

There are no global variables in C#. You should have such an variable as an instance variable in your form (or better yet, in a model for which your form is a view), and that is perfectly fine.

This is a very simple and stupid solution. I would use a MVP design pattern for this but here the fastest and simple solution:
//Declare a flag to block the processing of your event
private bool isEventBlocked = false;
private void OnTextChanged(object sender, EventArgs e)
{
if(!isEventBlocked)
{
//do your stuff
}
}
private void OnNewFile() //OR OnOpenFile()
{
try
{
isEventBlocked = true;
CreateFile();
}
catch
{
//manage exception
}
finally
{
isEventBlocked = false;
}
}