Reading from and writing to a text file.

[pbj2009]

Hello all:
I'm pretty stumped on this one. I'm not looking for Code, I'm just trying to figure out the best way to start this since I am new to reading and writing from files. I can't figure out what section (main/btnOpen/frmExceptionsLoad) to put the code and all tutorials have either reading from or writing to and I am confused about putting it together along with the calculations of course.

I have to write a program that when I click a Button control, it will read five scores (separate lines) from a text file , then calculate the average of the scores and then write the average of those scores in a separate text file while also making sure my program handles IOExceptions. :|

I am completely lost. Again, I'm not looking for code, just a push in right direction so I can figure this out. Can anyone help?

[GaryTexmo]

Well, for starters, take a look at the classes in the System.IO namespace. There are various stream readers/writers that will handle the file IO for you. If you get stuck, try a google search for "C# read write file" or something like that, there's tons of references.

For the general program flow, it depends on what you want to accomplish. It sounds like the event handler for the button click event is as good a place as any for your code. If you want to get more elaborate, you can have controls to display the scores and manipulate the data.

For example, you can have a button that uses an OpenFileDialog to get a file name, then loads the scores into a text or list box. Then you can have a button called operate (or something) which does the operations and updates the text box. Then another button called save, which does the obvious.

C# is like programming with Lego. I hope that gives you some ideas and a starting place. Have fun, and good luck! :)

[tlhintoq]

As for some general tips on program structure... That's more a matter of someone's style. But in general one should try to keep methods some and have descrete reusable purposes, rather than one big function.

I'm not a fan of putting all your code in the actual MyButton_click handler. That makes it hard to call again from someplace else. At first it may seem more convoluted to do it this way, but in as your programs get longer, this can really save you.

#region Properties and variables
List<int> MyScores;
String FilePath;
#endregion Properties and variable
 
#region Construction/Destruction methods
// The new form method
// The Form_Load method
// Form closing method
#region Construction/Destruction methods
 
MyButton_click(object sender, eventargs e)
{
    DoMyProcess(); // Go to a method for handling this
}
 
DoMyProcess()
{
     DoStepOne();
     DoStepTwo();
     DoStepThree();
}
 
DoStepOne()
{
     // Code for reading the file into a list.
}
 
DoStepTwo()
{
    // Code to do  your calculations
}
 
DoStepThree()
{
    // Code to update your results form
}
 

[pbj2009]

Thank you for the tips!

[GaryTexmo]

@tlhintoq
Tlhintoq makes a great point here... I'm somewhat embarrassed because I should have thought of that! To redeem myself, I'll throw out another tip to help you make your event handlers as generic as possible, to allow you to better reuse them.

As a part of the event handler, they give you the reference to the object that triggered the event itself, which is the parameter named sender. In wherever you handle this, you can cast sender to the type you're expecting, and if it's not null operate on it. A common thing I notice is that when people write event handlers, they access the member variable itself, instead of operating on sender, which means that handler is good for that object only.

Allow me to demonstrate with a quick little code snippet that should make my point pretty quickly. Make a new windows application and insert the following...

(Please note, I'm coding the controls via the constructor, not the designer, so you can better get the idea of what's going on)

        public Form1()
        {
            InitializeComponent();
 
            Button button1 = new Button();
            button1.Text = "Button1";
            button1.Location = new Point(8, 8);
 
            Button button2 = new Button();
            button2.Text = "Button2";
            button2.Location = new Point(button1.Location.X + button1.Size.Width + 8, 8);
 
            CheckBox checkbox1 = new CheckBox();
            checkbox1.Text = "CheckBox1";
            checkbox1.Location = new Point(8, button1.Location.Y + button1.Size.Height + 8);
 
            button1.Click += new EventHandler(GenericClickHandler);
            button2.Click += new EventHandler(GenericClickHandler);
            checkbox1.CheckedChanged += new EventHandler(GenericClickHandler);
 
            this.Controls.Add(button1);
            this.Controls.Add(button2);
            this.Controls.Add(checkbox1);
        }
 
        void GenericClickHandler(object sender, EventArgs e)
        {
            Button senderButton = sender as Button;
 
            if (senderButton != null)
            {
                MessageBox.Show("Button click event from: " + senderButton.Text);
            }
            else
            {
                MessageBox.Show("Sender was not a button!");
            }
        }
 

If you noticed, I threw in a checkbox and tied it to the same handler to show what happens when you get an object you're not expecting. I hope you found this informative :)