This really suprised me. One of the simplest things doesn't work, making a counter. I'm making a kinda game application in c# and there is also a timer who counts the time. Very simple right? I know how to code this and this is something I did before but I don't understand why it isn't working now.
int i = 0;
i++;
label1.Text = i.ToString();
label1.Text turns in to 1 and nothing else happens. Also tryied this with a timer but it freeezes in 1. I know this post isn't really going to help other people but it is very frustrating.
Why you are always getting 1 in your label1 text?
The reason is very simple, each time you are getting to the first line, i is 0:
// Line 1
int i = 0; // declaring and setting i to 0
// Line 2
i++; // incrementing i to 1
// Line 3
label1.Text = i.ToString(); // displaying i (which is equal to 1)
and then again you are getting to the Line 1 and setting i=0, etc...
I presume you have a UI application (win form, web form etc...)
You already mentioned you have a timer that works fine and a label where you output the incremented i variable.
As already commented in order to see a change in your label you can use a loop as following:
int length = 100; // for example
for (int i = 0; i < length; i++)
{
label1.Text = i.ToString();
}
The output in label1 text will be 0, then 1, then 2 .... and finally 99.
Obviously you won't be able to see all those values except the last one 99 at run-time but you can debug and see how it works.
I presume, what you needed is to have your label text changing each time the timer will tick.
Following a code example how you could implement it:
private int i = 0; // initialized once in this UI class
private void timer1_Tick(object sender, EventArgs e)
{
label1.Text = i.ToString();
i++; // will increment by one each time the timer is ticking
}
Set your timer interval to ~1000 so you could clearly see how your text label increments at run-time.
If you want to increment it you have to add the incrementing logic in a loop like for or while loop:
If you want to use timer to count something please refer to this question : here
Related
When I do this for loop on a windows form app and I click a button to start this for loop, the label just changes to the last item in the array, how do I get it to go through the array one at a time?
for (int i = 0; i < WordsnQuestions.questions.Length; i++)
{
lblScrambled.Text = WordsnQuestions.questions [i++];
}
The loop is too fast... the label changes for every item in the loop (note: loop, not array, because of another issue), but the form doesn't have a chance to repaint anything until after the loop is already finished. By this time we're already up to the last item, so that's what we see.
The typical fix for this is move the index outside of the method, and only show one item for each event:
int currentPosition = 0;
public void btnNext_Click(object sender, EventArgs e)
{
lblScrambled.Text = WordsnQuestions.questions [currentPosition++];
if (currentPosition >= WordsnQuestions.questions.Length) currentPosition = 0;
}
Separate from this, the original code incremented the counter twice per loop iteration... but again, properly designing the interaction avoids this in the first place.
But let's say you wanted an animation effect. Then you might try something like this to slow things down (note only one increment operator is used):
for (int i = 0; i < WordsnQuestions.questions.Length; i++)
{
lblScrambled.Text = WordsnQuestions.questions [i];
Thread.Sleep(1000);
}
But this still won't work, because the code still does not yield control back to the form so it can repaint the window.
Now you might be tempted to do something like this:
for (int i = 0; i < WordsnQuestions.questions.Length; i++)
{
lblScrambled.Text = WordsnQuestions.questions [i];
Application.DoEvents();
Thread.Sleep(1000);
}
This will seem to (finally!) work, because it does allow an event loop to finally process each of WM_PAINT messages. However, there are still all kinds of problems with it. Again, the correct solution is really to think more carefully about how the interaction should work in the first place.
There are two issues here:
i++ is twice so your skipping items #2, 4, 6... and looping over 1, 3, 5 ... etc
lblScrambled.Text will have the last item and program will not fail if you have odd number of items.
Here is the updated code for you to try:
for (int i = 0; i < WordsnQuestions.questions.Length; i++)
{
lblScrambled.Text += WordsnQuestions.questions [i];
}
When I clicked button starts for loop from i=0 and I want to see on the label value of i. However I only see last values of i.
public partial class Form1 : Form
{
int i;
public Form1()
{
InitializeComponent();
}
private void btnclick_Click(object sender, EventArgs e)
{
for ( i = 0; i < 3; i++)
{
lblForLoopExample.Text = i.ToString();
System.Threading.Thread.Sleep(1000);
}
}
}
when I run the my code I only see on the label ; 2 .
I want to see such a like below;
When the started For loop, i = 0, I must see the 0 on the Label.Text. An then when the i = 1, I must see 1 on the label.Text. And when i = 2, I must see 2 on the Label.Text.
I added Thread.Sleep(1000) however, result didn't change.
Where I am make mistake?
Please help me,
if you help me , I will appreciate you.
Thanks,
You need to append the lbl to get all the values. Right now, it finishes the loop and give you the last value in your label
public partial class Form1 : Form
{
int i;
public Form1()
{
InitializeComponent();
}
private void btnclick_Click(object sender, EventArgs e)
{
for ( i = 0; i < 3; i++)
{
lblForLoopExample.Text + = i.ToString();
}
}
}
Your problem is that you're doing work on the UI thread while expecting the UI thread to update your form.
While you process your loop, the UI thread is actually executing this code. The UI thread is therefore unable to update the form with the intermediate values you are setting within the loop. Once your code completes, the UI thread is then free to update the form. That's why you see the last value only.
You can see this better if you updated your code to loop ten million times instead of 3. Your form will become unresponsive and will appear locked up. That's because Windows knows your UI thread is locked in an intensive process and is unable to update the UI.
The solution is to use a background thread to run your process and synchronize updates with the UI thread. You'll also have to slow your loop down to see the changes, as others have suggested.
To learn more about how the UI thread works, and how to synchronize background threads with it, read this article (it's about WPF, but it covers the general case).
Each loop you re-write the string. Instead of saying
lblForLoopExample.Text = i.ToString();
You need to add to the string on each iteration. I'd create a variable to hold the value, and so something like this:
string myString = string.Empty;
for(i=0;i < 3; i++)
{
myString += i.ToString() + ", ";
}
lblForLoopExample.Text = myString.substring(0, (myString.length - 1));
substring is just so you don't have that trailing comma. It's kind of dirty code, but it will work.
First of all, your code won't compile as you are missing the exact format of the ToString() method in i.ToString along with the ;
lblForLoopExample.Text = i.ToString();
^^^
As per your code, you should try this:
for ( i = 0; i < 3; i++)
{
lblForLoopExample.Text += i.ToString() + ", ";
}
I am extremely very new to C#, just wrote some calculator, text editors and DB client in the school almost 10 years ago :) Not I am trying to make a tool for myself and my colleagues to view traces and logs in easier way. All we know Notepad++, we used daily for text highlighting, styling, but the thing is that these highlights get lost after you close Notepad++.
So my goal now is to make the same text editor but so it will be able to save your work.Currently I am working on the feature so when I am selecting some text, it will search for the same on whole document and highlight it, for example with red background. I added this one:
private void richTextBox1_SelectionChanged(object sender, EventArgs e)
{
int startIndex = 0;
while (startIndex<richTextBox1.TextLength)
{
int wordStartIndex = richTextBox1.Find(richTextBox1.SelectedText, startIndex, RichTextBoxFinds.None);
if (wordStartIndex != -1)
{
richTextBox1.SelectionStart = wordStartIndex;
richTextBox1.SelectionLength = richTextBox1.SelectionLength;
richTextBox1.SelectionBackColor = Color.Red;
}
else
break;
startIndex += wordStartIndex + richTextBox1.SelectionLength;
}
}
But it gives me "StackOverFlow" as I have a loop here. Can you please assist me with it?
I think I need to run 2 searches to avoid loop - one before selection index, one after. Or maybe there is easier option?
Thank you all, guys!
You're getting an infinite loop because you're in an event that checks for a selection change, and then in that event, you're changing the selection, which causes an event, where you change the selection, which causes an event...
If you want to avoid this you'll need a class level variable like
bool inSelectionChangeEvent;
and then change your code to:
private void richTextBox1_SelectionChanged(object sender, EventArgs e)
{
if (!inSelectionChangeEvent){
inSelectionChangeEvent = true;
}
else{
return;
}
...
Also, you're writing your OWN text editor? Err, there may be a simpler solution :)
Your problem is with the selection length. Right here:
richTextBox1.SelectionLength = richTextBox1.SelectionLength;
It does no good to set something equal to itself and I'm guessing this was an accident. When the SelectionLength is 0, startIndex never increases (anything + 0 is anything).
The first thing I'd do is check if richTextBox1.SelectionLength < 1 and if it is, just return from the method without doing anything.
This code snippet from MSDN should help you accomplish what you're doing:
string wordToFind = "melp";
int index = richTextBox1.Text.IndexOf( wordToFind );
while( index != -1 )
{
richTextBox1.Select( index, wordToFind.Length );
richTextBox1.SelectionColor = Color.Red;
index = richTextBox1.Text.IndexOf( wordToFind, index + wordToFind.Length );
}
I am creating a windows form that is a random number guessing game. I've made these before in C++ and never had an issue, however I have a big one here- I have no idea how to get the user back to input a number after the loop has began running. Here is my code:
private void btnGuess_Click(object sender, EventArgs e)
{
int guess = 0;
int count = 0;
int accumulator = 0; // accumulator
Random rand = new Random();
int number = rand.Next(1, 100);
txtAnswer.Focus();
while (guess != number)
{
guess = int.Parse(txtAnswer.Text);
if (guess < number)
{
MessageBox.Show("Too Low! Guess again!");
txtAnswer.Text = "";
txtAnswer.Focus();
count++;
accumulator++;
}
else if (guess > number)
{
MessageBox.Show("Too High! Try again!");
txtAnswer.Text = "";
txtAnswer.Focus();
count++;
accumulator++;
}
else
{
MessageBox.Show("Correct! you guessed the number in " + accumulator + " tries!");
break;
}
}
}
}
}
I just filled the while loop arguments with something for you guys, even though i know it won't work. Basically, I need to run the loop, get feedback (if the users guess was too high or low) then get the user to be able to input another number BEFORE the loop runs again. I don't know how to get that to happen with a text box control which is where the input will be. Any ideas?
You should not loop inside in the btnGuess_Click. Instead you need to store the state (the number, count, and the accumulator variables) in the scope of the form itself.
Initialize the random number when the form loads, or using some kind of start button.
Then inside the guess button handler, read the text box value and compare it to the number variable, such as what you are doing currently.
What you are building is more a console style application. So there is 1 main loop that is executing all the code.
In forms applications it is an event driven environment. So the user gets a form, presses a button, the form is evaluated and then the method handling ends.
So you have on a class level some variables for counts, in the constructor you add the initialization and the method for submit will be something like
private void btnGuess_Click(object sender, EventArgs e)
{
//Increment counters
//Check
//Show feedback
//Leave the button click code
}
For some more info, check this out:
https://msdn.microsoft.com/en-us/library/dd492132.aspx
i have a timer that changes a label's text each tick. For some reson, it stop and does not continue looping. Why?
private int count = 0;
private void timer1_Tick(object sender, EventArgs e)
{
string[] arr4 = new string[3]; // 4
arr4[0] = "one";
arr4[1] = "two";
arr4[2] = "three";
if (count == 4)
{
count = 0;
}
toolStripStatusLabel1.Text = arr4[count];
count++;
}
Also, when my form loads, the label's text is blank. Then it goes to arr4[0]. When it loops again, the text starts at arr[0]. Why is the text blank first, and how do i fix it?
Looks like your original question was answered in the comments. I'll answer your second question from the comments.
Your timer1_Tick event doesn't execute immediately when your program starts. The first time it executes is after 5000ms, in your case. So the label will show blank at first, then change to the value of arr4[0]. If you don't want that, you could:
set the value of the label in the designer at design time
set the value of the label in the constructor at run time
pull the creation of the array out of the timer tick event so you're not recreating it every 5 seconds, make it a class variable, and create it in the constructor and then set the label to arr4[0] immediately after creating it