Develop Reference

How to use functions step by step

Sorry for the strange title, I just don't know how to name this question.
So I have such a function say().
void say(string printedText) {
gameText.text = printedText;
}
And I need to use it several times. Something like this:
say("test text 1");
say("test text 2");
say("test text 3");
...
I need to change text by clicking Space button. Of course I need to use something like this:
if(Input.GetKeyDown(KeyCode.Space)) {
...
}
But I can't understand how to show text step by step. So for example if I click Space button once I should see "test text 1". Next click should show me "test text 2" etc.
How can I realise it? Thanks in advance.

Depending on your needs you could store different texts in a List<string> or maybe even Queue<string> and do
List example
// Add your texts in the editor or by calling texts.Add(someNewString)
public List<string> texts = new List<string>();
private int index = 0;
if(Input.GetKeyDown(KeyCode.Space))
{
// have a safety check if the counter is still within
// valid index values
if(texts.Count > index) say(texts[index]);
// increase index by 1
index++;
}
Array example
Basically the same as the List<string> but you can't add or remove elements "on the fly" (at least not that simple)
public string[] texts;
private int index = 0;
if(Input.GetKeyDown(KeyCode.Space))
{
// have a safety check if the counter is still within
// valid index values
if(texts.Length > index) say(texts[index]);
// increase index by 1
index++;
}
Queue example
public Queue<string> texts = new Queue<string>();
for adding a new text to the end of the queue do
texts.Enqueue(someNewString);
and then
if(Input.GetKeyDown(KeyCode.Space))
{
// retrieves the first entry in the queue and at the same time
// removes it from the queue
if(texts.Count > 0) say(texts.Dequeue());
}
Simple counter
If it is really just about having a different int value then yes simply use a field
private int index;
if(Input.GetKeyDown(KeyCode.Space))
{
// uses string interpolation to replace {0} by the value of index
say($"test text {0}", index);
// increase index by one
index++;
}

define a class field like this:
int count = 0;
and now everytime space is hit:
if(Input.GetKeyDown(KeyCode.Space)) {
say("test text " + count);
count = count + 1;
}

This Code:
if(Input.GetKeyDown(KeyCode.Space)) {
...
}
only works for Unity, In Visual Studio you'll have to create an Event to whatever object you want to do this, for example, if you want to call a void each time you press spacebar youll have to do this, it is easy: (Image below)
In the propieties window press the bolt icon and after double click on the event you want to create (samples): TextChanged, LocationChnaged, MouseMove, etc...
I will use KeyDown on the TextBox object
image
Now in your code this void should be generated
image
Inside this void i writed the code and this is how it looks:
(put int n = 1 before voids)
private void textBox1_KeyDown(object sender, KeyEventArgs e)
{
if(e.KeyCode == Keys.Space)
{
//int n = 1; must be defined
textBox1.Text = "test text " + n;
n++;
}
}
Now each time you'll press or stay pressed spacebar the textbox will be filled with "test text " and the value will be 1 more each time.

Logic trouble with loop

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

C# event click containing more than one method

I am trying to nest methods, or place methods within other methods. Using C# and Microsoft Visual Studio for the first time and my dilemma is this. I have created form with an event click button to validate user input, which is fine in itself, but I need to validate more than one input when the button is clicked. In the Calculate button’s click event handler, perform input validation on the three text boxes (the three that the user will use for data entry). For code efficiency I want to use separate methods to achieve this. I have tried writing more methods directly within the event handler, but no matter how I start the method public, private, static, void, main etc I always get errors. Any assistance/advice would be greatly appreciated.
private void btnCalculate_Click(object sender, EventArgs e)
{
int txtLength = 0;
if ((txtLength < 5) & (txtLength > 50))
MessageBox.Show("Length measurement is invalid" + "\r\n" + "Please enter a value between 5 and 50", "Data Invalid");
int txtWidth = 0;
if ((txtWidth < 2) & (txtLength > 20))
MessageBox.Show("Width measurement is invalid" + "\r\n" + "Please enter a value between 2 and 20");
int txtAvgDepth = 0;
if ((txtAvgDepth < 2) & (txtAvgDepth > 4))
MessageBox.Show("Width measurement is invalid" + "\r\n" + "Please enter a value between 2 and 20");*/
}
Changed code in method along with the error messages it throws. The original code had no syntax errors.
Problem solved. Thank you all very much for your help :)

Just add them to the class:
private void CalculateButton_Click(object sender, EventArgs e)
{
ValidateLength();
ValidateWidth();
ValidateDepth();
}
private void ValidateLength()
{
int txtLength = LengthTextBox.Value;
if ((txtLength < 5) & (txtLength > 50))
MessageBox.Show("Length measurement is invalid" + "\r\n" + "Please enter a value between 5 and 50", "Data Invalid");
}
private void ValidateWidth()
{
int txtWidth = WidthTextBox.Value;
if ((txtWidth < 2) & (txtLength > 20))
MessageBox.Show("Width measurement is invalid" + "\r\n" + "Please enter a value between 2 and 20");
}
private void ValidateDepth()
{
int txtAvgDepth = DepthTextBox.Value;
if ((txtAvgDepth < 2) & (txtAvgDepth > 4))
MessageBox.Show("Depth measurement is invalid" + "\r\n" + "Please enter a value between 2 and 4");*/
}
I guess you're trying to tidy this up and have a single validation routine:
private void CalculateButton_Click(object sender, EventArgs e)
{
ValidateRange(LengthTextBox.Value, 5, 50, "Length");
ValidateRange(WidthTextBox.Value, 2, 20, "Width");
ValidateRange(DepthTextBox.Value, 2, 4, "Depth");
}
private void ValidateRange(int value, int min, int max, string msg)
{
if (value < min || value > max)
MessageBox.Show(
string.Format("{0} measurement is invalid\r\nPlease enter a value between {1} and {2}", msg, min, max),
"Data Invalid");
}

Click Handlers are known as delegates, they subscribe to events in a one-event, many subscribers fashion. What you are trying to achieve is completely possible but not from the IDE GUI, as it is designed to manage a single subscription. You could instead subscribe to the event from code like this
btnCalculate.Click += ClickHandler1;
btnCalculate.Click += ClickHandler2;
btnCalculate.Click += ClickHandler3;
Even though it's possible, i'd strongly advise against it as it seems over-engineered and it's not really how the platform was thought out to be used. It shouldn't have any bad side effects as the .Net event/delegate system is ready to handle this use case but the maintainability suffers in the process.
I'd rather go with an orchestrator method. Subscribe once and call each validation method from there.
More reading material:
https://msdn.microsoft.com/en-us/library/17sde2xt%28v=vs.90%29.aspx
https://msdn.microsoft.com/en-us/library/bb534960(v=vs.110).aspx
https://msdn.microsoft.com/en-us/library/018hxwa8(v=vs.110).aspx

Computing Form Location with Button

I'm working on a programming assignment, and I'm trying to make this button take the values from two textboxes, and calculate the new location for the form window. I'm having trouble converting the textbox values to type int, and being made usable by the btnCompute_click method.
private void btnCompute_Click(object sender, EventArgs e)
{
int x = Convert.ToInt32(txtXvalue);
int y = Convert.ToInt32(txtYvalue);
Location = new Point(x,y);
}
private void xValue_TextChanged(object sender, EventArgs e)
{
int xValue =
Convert.ToInt32(txtXvalue);
}
private void yValue_TextChanged(object sender, EventArgs e)
{
int y =
Convert.ToInt32(txtYvalue);
}
I forgot to add some additional info, the acceptable values for x and y must be positive. Would I use an if...else statement to control the acceptable values?

user29... i have no idea why death... replied that. it makes no sense to me. but you question makes sense to me. i suppose death... did not understand your question.
First off, everything you ask does not need anything in the TextChanged methods.
Do all your handling in the btnCompute_Click() method because you want to do something *when you click your button, not when the user edits the text of the text boxes, according to your question.
The code that is in your TextChanged() methods will get executed whenever the Text values of those text boxes change. that's not what you asked for it to do. But you could use these events for example, if you wanted a label to become visible or hidden and to set the text of a label which shows text, so you can use it as an error message label, for instance if the integer value of a text box is negative or even if it cannot be parsed.
So in your btnCompute_Click() methods, you first want to get the int values. You need to decide exactly what you want your code to do if the text is not integers. In my opinion, most beginners code things like message boxes or something. I like to give the user feedback with Labels or a status bar message, depending on what I feel is appropriate. Since my first choice would be to use a Label to show the 'error' message when text boxes cannot be parsed to integers, then i would simply return from the button click method without doing anything when the values are not what i want. That way the user gets their messages without annoying popup message boxes or anything. But it's up to you whether you want to pop up a message box or not. Others have given you good code to do that. I want to give you good code that avoids what i consider annoying popup boxes.
When converting strings to an int, Convert.ToInt32 will throw an error if the string cannot be parsed. int.TryParse is the silver bullet for truly parsing strings to integers without any error. Here is the entire code i would use. I made a new project just to make sure i'm not giving you buggy code. I give you my code on how I handle this.
In your updated prerequisite, you mention x & y must be positive and not negative. I note to you that these are not the same. For instance, 0 is neither positive nor negative. I assume that you technically mean that x and y cannot be negative, (and that it does not need to be positive, since 0 should be allowed).
private void Form1_Load(object sender, EventArgs e)
{
lblErrorX.Text = null;
lblErrorY.Text = null;
}
private void btnMoveForm_Click(object sender, EventArgs e)
{
int x = 0; if (int.TryParse(txtX.Text, out x) == false) { return; }
int y = 0; if (int.TryParse(txtY.Text, out y) == false) { return; }
if (x < 0 || y < 0) { return; }
this.Location = new Point(x, y);
}
private void txtX_TextChanged(object sender, EventArgs e)
{
int x = 0;
if (int.TryParse(txtX.Text, out x) == false)
{ lblErrorX.Text = "X is not an valid integer."; return; }
if (x < 0) { lblErrorX.Text = "X cannot be negative."; return; }
lblErrorX.Text = null;
}
private void txtY_TextChanged(object sender, EventArgs e)
{
int y = 0;
if (int.TryParse(txtY.Text, out y) == false)
{ lblErrorY.Text = "Y is not an valid integer."; return; }
if (y < 0) { lblErrorY.Text = "Y cannot be negative."; return; }
lblErrorY.Text = null;
}
In my project, on the form, in the following left to right order: lblX, txtX, lblErrorX. I have the same corresponding for Y: lblY, txtY, lblErrorY. Then i have one Button: btnMoveForm. So my txtX corresponds to your txtXvalue. my btnMoveForm corresponds to your btnCompute, but to me, 'compute' means to calculate, which is not really what this button is doing. this button is moving the form, so that's why i name it as such.
I have played with setting both the Location and the DesktopLocation and it seems to do the same thing. I've always used Location and i just learned that DesktopLocation works too, but since Location is shorter, i use it.
Someone asked why i don't use if(!int.TryParse(...)) { return; } rather than my if(int.TryParse(...) == false) { return; }. My reason is unfortunately that i think ! is an easy one character to miss when reading code, so i avoid it, especially when that little mistake means the opposite of what the code really would do. So my use of '== false' is always for human clarity. But i do like the C# ease of only needing one character. I just think it's a shame that in my opinion, it's a lot safer to write code that is better for humans so we don't mistake it. That's the only reason i use '== false' instead of !. Use ! if you like. It's quite convenient. I regret not using it. hehe.
Oh, and the reason i set the lblErrorX.Text = null; and lblErrorY.Text = null; is on my form in design view, i give them a text value so i can see them. :) so when the program runs, i set the Text to be blank. But you can use the Visible property if you prefer. I just leave them always visible and only set their Text properties.

Based on your expanded criteria you can check for negative numbers conditionally or use Math.Abs to get the absolute value. Something like this.
int x, y;
if (int.TryParse(txtXvalue.Text, out x) && int.TryParse(txtYvalue.Text, out y))
{
if (x < 0 || y < 0)
{
MessageBox.Show("Negative numbers not allowed");
}
else
Location = new Point(x, y);
}
else
{
MessageBox.Show("Must be an Integer");
}
or
int x, y;
if (int.TryParse(txtXvalue.Text, out x) && int.TryParse(txtYvalue.Text, out y))
{
Location = new Point(Math.Abs(x), Math.Abs(y));
}
else
{
MessageBox.Show("Must be an Integer");
}

I think you are looking for this.
private void btnCompute_Click(object sender, EventArgs e)
{
int x = Convert.ToInt32(txtXvalue.Text);
int y = Convert.ToInt32(txtYvalue.Text);
DesktopLocation = new Point(Math.Abs(x), Math.Abs(y));
}
This gets the location for the desktop. Also you need the .Text to get the text inside the textbox. You should also check to make sure the text is not null or empty before using or it will cause an error.
If this isn't what you are looking for please explain a little more.

Adding multiple expanders event programmatically wont work

I've got a problem with adding Expanded event to my Expanders. I have expanders on my Window and I want to get the effect when I expand my expander all other will go down. I write functions that let me do this and it work correct. The problem is that I have 96 expanders I don't want add 96 events for Expand and 96 events for Collapse so I thought that I can add this programmatically.
look at the code:
private void InitExpanders()
{
var expanders = GetExpanders(); // List<Expander> - list of expanders
for (int i = 0; i < expanders.Count; i++)
{
if (i % 6 == 1)
{
expanders[i - 1].Expanded += new RoutedEventHandler(delegate(object sender, RoutedEventArgs args)
{
DisableBigExpanders(1); // problem is here!
});
}
}
}
this code works fine but for each expander function parameter will be 1.
Ive tried to add integer and increment it but it wont works.
private void InitExpanders()
{
var expanders = GetExpanders();
int x = 0;
for (int i = 0; i < expanders.Count; i++)
{
if (i % 6 == 1)
{
expanders[i - 1].Expanded += new RoutedEventHandler(delegate(object sender, RoutedEventArgs args)
{
DisableBigExpanders(x);
});
x++;
}
}
}
Thanks for all replies.

I suspect you are finding x in the delegate is always the highest value it reached during the loop. This is due to the way the compiler instantiates the instance of the anonymous method you've defined. It looks at what captured outer variables there are around the delegate and decides whether it requires separate instances or if it can use a single instance. In this case, you have no captured outer variables; therefore, the compiler is permitted to use the same instance of the delegate and therefore the same value of x.
To get around this issue, all you need to do is add a more granular variable just before the delegate and assign it the value of x. This will work:
private void InitExpanders()
{
var expanders = GetExpanders();
int x = 0;
for (int i = 0; i < expanders.Count; i++)
{
if (i % 6 == 1)
{
int y = x++;
expanders[i - 1].Expanded += delegate
{
DisableBigExpanders(y);
};
}
}
}
See here for more info on the theory: http://en.csharp-online.net/ECMA-334%3A_14.5.15.4_Anonymous_method_evaluation