Try/Catch Statements

Hello there! I am fairly new to C# and I'm having a problem coding a specific assignment. I was wondering if anyone could provide a few tips on what I'm doing wrong. I'm trying to have it catch 3 different things. That there is a decimal value, that there actually is something inserted, and that the number is within range of 0 and 1000. All of these need to display a different message box also. Down below is so far what I've done. I'm able to do the valid range but it's still calculating the numbers when I click calculate. Aslo when there is no value entered it brings up the "Please enter a valid subtotal" message box instead of the "Requires Subtotal" box. Thanks!

Code:

---

private void btnCalculate_Click(object sender, EventArgs e)
        {
            try
            {
               
               
                decimal subtotal = Decimal.Parse(txtSubtotal.Text);
                if (subtotal < 0 || subtotal > 1000)
                {
                    MessageBox.Show("Please enter a valid range");
                    txtSubtotal.Focus();
                                    }
                if (txtSubtotal.Text == "")
                {
                    MessageBox.Show("Requires Subtotal");
                    return false;
                }
               
                          decimal discountPercent = .25m;
                decimal discountAmount = subtotal * discountPercent;
                decimal invoiceTotal = subtotal - discountAmount;

                discountAmount = Math.Round(discountAmount, 2);
                invoiceTotal = Math.Round(invoiceTotal, 2);

                txtDiscountPercent.Text = discountPercent.ToString("p1");
                txtDiscountAmount.Text = discountAmount.ToString();
                txtTotal.Text = invoiceTotal.ToString();

                txtSubtotal.Focus();

                Convert.ToDecimal(txtSubtotal.Text);     
            }
            catch (FormatException)
            {
                MessageBox.Show("Please enter a valid subtotal");
            }
         
        }

---

It works just as you designed it.

This line

Code:

---

decimal subtotal = Decimal.Parse(txtSubtotal.Text);

---

Throws a FormatException if the value is unabled to be parsed. And the code in the catch statement i executed.
Run the code in the debuger and you see where the exception occurs.

Let's think about the logic of your program, in comments:

Code:

---

                //convert the value the user typed into a decimal
                decimal subtotal = Decimal.Parse(txtSubtotal.Text);

                //check it's within range
                if (subtotal < 0 || subtotal > 1000)
                {
                    MessageBox.Show("Please enter a valid range");
                    txtSubtotal.Focus();
                }

                //check if the user typed anything or not
                if (txtSubtotal.Text == "")
                {
                    MessageBox.Show("Requires Subtotal");
                    return false;
                }
               
                          decimal discountPercent = .25m;

---

Can you see a problem?


Here's a clue, I've stripped the code, leaving just 2 relevant comments:

Code:

---

//first, take the value the user typed, and convert it to a decimal
 //then, check if the user typed something

---

What strikes you about this logic? :)


-

When you start off in programing, write the commentfirst in plain english and embody the logic, then turn the comments into code. You end up with a program that works because you first wrote it in the language that you think in, and you have a beautifully commented code at the end
Good result!

cool...

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