Hello, I am having trouble making try catch work with do while.

[stefan nesic]

Hello there,

I am following a course in C#, and am having trouble making try catch work with a do while loop.
I have searched the internet for the correct way of doing this, but it all doesn't seem to work.

Here is the code thusfar.

        private void button1_Click(object sender, EventArgs e)
        {

            int number = 0;// ik maak twee int variabelen om mee te rekenen
            int multiply = 1;

            number = int.Parse(txbGetal.Text);//hiermee zet ik de invoer in het tekstvak om in variabel number.








            do //// hier begint de for loop, met deze code loopt multiply op van 1 naar 10.
            {

                txbTafel.Text = txbTafel.Text + "\r\n" + number * multiply++ + "\r\n";// met deze code reken je uiteindelijk.. (number* multiply)..en toon je dez uitkomst in het tekstvak, onder elkaar ( "\r\n" )




            }

            while (multiply <= 10);


            }

        }
    }

it is a program that shows the multiplication table of a entered number, as long as the number is between 2 and 12.
I am looking for the right code and hopefully an explanation.
( i can make try catch work without do while)

thanks in advance for any help,

Greetings,

Stefan

[Tim Holloway]

It's kind of hard to make a try/catch work when you haven't coded either a try or catch statement.

Also, all those blank lines make your sample nearly impossible to read!

[stefan nesic]

Hello Tim,

I apologize for my initial post.. it was late at night and it was driving me crazy ( new at programming crazy)

Here is the code with a try catch block:

 private void button1_Click(object sender, EventArgs e)
        {

            int number = 0;// ik maak twee int variabelen om mee te rekenen
            int multiply = 1;


            try
            {
               number = int.Parse(txbGetal.Text);
               do 
                {

                    txbTafel.Text = txbTafel.Text + "\r\n" + number * multiply++ + "\r\n";
                      
                }

                while (multiply <= 10);
                while (number > 12) ;///this is what i was trying now, does freeze the program up, doesn't work.
            }

            catch (Exception)

            {
                MessageBox.Show("Zoek dit uit");

            }

        }

    }
}

the above adding of while (number>12) doesn't work. It does freeze up the program when >12 is entered.
I have looked online for the solution, as a understand it can work with a if statement, but i couldn't make this function either.
Hopefully someone here has a answer.
If someone does, and has the time, I would also like to know how a try catch work with a for loop.

thanks for any help in advance,

Stefan.

[Rob Spoor]

stefan nesic wrote:

while (number > 12) ;///this is what i was trying now, does freeze the program up, doesn't work.

That while isn't part of the do-while above it - it's a separate while with an empty body. It's equivalent to this:

while (number > 12) {
    // do nothing
}

So either this loop ends directly if number <= 12, or it loops forever because number > 12 will always be true.

[stefan nesic]

Hello Rob,

I have though about what you were saying, number is either <12 or >12, its just that there is no code that is executed when  >12.
I cant find anywhere in the textbook how to code this..

am i thinking in the right direction if i make a do while loop, with a try catch, using if statements?
if so where?

I have already tried this, but i keep getting bracket problems.

Is anybody kind enough to provide the functioning code (or construction as i call it)??

thanks a lot.

Stefan.

[stefan nesic]

I have tried several things including code below, and i cant get it to work.


code:

        private void button1_Click(object sender, EventArgs e)
        {

            int number = 0;// ik maak twee int variabelen om mee te rekenen
            int multiply = 1;

            try
            {
                number = int.Parse(txbGetal.Text);
                do
                {

                    txbTafel.Text = txbTafel.Text + "\r\n" + number * multiply++ + "\r\n";

                }
                while (number <= 12);

            }


            catch (Exception)

            {
                MessageBox.Show("Zoek dit uit");

            }


        }
    }

}

in this code it just repeats the number if above 12...

I will work on some other parts of homework that need final touches because this is driving me crazy..

[Campbell Ritchie]

stefan nesic wrote:. . . it was late at night . . .

You should probably then go to bed; you can only program when you are awake.
The comments add nothing to the code; it should be obvious that you are reading and multiplying two numbers.
What good does your try‑catch do? You are not going back to the original input and correcting it, and I think the error message isn't going to help the user. You can stop the method and issue a message saying to correct the input, and click the button again. Or you can wrap the try‑catch in a loop:-

bool needsReading = true;
int i;
do
{
   try
   {
      i = int.parse(txbGetal.Text);
      needsReading = false;
   }
   catch (...)
   {
      ...
      /*
       * Needs some means to delay the loop
       * until input has been corrected
       */
   }
} while (needsReading);
// etc

The first technique is probably better: put the reading in one method and the multiplication into another method.
Look up Hungarian Notation; I don't like the format of variable names like txbGetal.