Simple adding windows program

Hello guys,

I was programming this simple adding numbers program and I thought about developing it more and more

The First code is :

Code:

---

        Dim number1, number2, sum As Integer
   
        number1 = TextBox1.Text
        number2 = TextBox2.Text
        sum = number1 + number2
        TextBox3.Text = sum
        MessageBox.Show("Thank you for using me.")

---

Not that text box 3 is read only !

Now I want to make the program give an error message it the input in textbox1 and textbox2 was nothing or not integer (number)

How i do that

I tried :

Code:

---

if TextBox1.Text = "" then
MsgBox("ERROR")


end if

---

but I keep getting error that it cannot convert Integer to String !

Any Ideas ??


THANKS,

That check shouldn't cause your error so I suspect your problem is that your not exiting on an error state. Post your whole code.

Parsing the value in the text box works.

vb Code:

number1 = Integer.Parse(TextBox1.Text)

Edit:

Use it like so:

vb Code:

Public Class Form1
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim number1, number2, sum As Integer
        If Not TextBox1.Text = "" Then
            number1 = Integer.Parse(TextBox1.Text)
            number2 = TextBox2.Text
            sum = number1 + number2
            TextBox3.Text = sum
            MessageBox.Show("Thank you for using me.")
        Else
             MessageBox.Show("ERROR")
        End If
    End Sub
End Class

You should always check the user inputs. A proper validation should be done before doing the actual operation.

It's better to use Integer.TryParse() method to "try" converting the value from the TextBoxes to an Integer value.

Here's the example:

vb Code:

Public Class Form1
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        '~~~ Declaring the variables
        Dim num1 As Integer
        Dim num2 As Integer
        Dim result As Integer
 
        If Integer.TryParse(TextBox1.Text, num1) Then   '~~~ we are trying to convert the value of 'TextBox1' to Integer value. If success, the value would be stored in 'num1' variable.
            If Integer.TryParse(TextBox2.Text, num2) Then   '~~~ Now, we are going after the second value. That is, trying to convert the value of 'TextBox2' to Integer value. If success, the value would be stored in 'num2' variable.
                result = num1 + num2    '~~~ we got the two values. So, we are adding them and storing the result in the variable named 'result'
 
                '~~~ Now displaying the result
                MessageBox.Show(String.Format("{0} + {1} = {2}", num1.ToString, num2.ToString, result.ToString))    '~~~ We are going to display the result in a MessageBox. We are using String.Format() function to format the string with placeholders.
            Else    '~~~ if the conversion of value from "TextBox2" to Integer fails..
                MessageBox.Show("Second number should be a valid integer !", "Error")
            End If
        Else    '~~~ if the conversion of value from "TextBox1" to Integer fails..
            MessageBox.Show("First number should be a valid integer !", "Error")
        End If
 
    End Sub
End Class

:wave: