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VB Implicit Conversion

Posted on 2010-09-16
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Last Modified: 2013-12-25
I'm currently in school and we are concentrating in VB for the most part, so I wanted to mess around and create a calculator. Everything was going smooth until I ran into this problem.

"Option Strict On disallows implicit conversions from 'string' to 'double'. (Line 18)

From what I see in my code, why in the world would it even be trying to convert to double? I'm saying the text from the textbox, which is a string equals value from the textbox plus the value one, but I'm using the ToString() method. So why is it trying to make an implicit conversion to double? I even tried to use the CDbl method to convert intOne to double just to see what it would do, but this is not the answer. It is clear that intOne is declared as an Integer data type. I know this is really easy, but I just can't figure it out.
Private Sub btnOne_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOne.Click
        Dim intOne As Integer = 1
        If txtDisplay.Text = "0" Then
            txtDisplay.Text = String.Empty
            txtDisplay.Text += intOne.ToString()
        Else
            txtDisplay.Text += intOne.ToString()
        End If

        If obj.AddBtn = True Then
            txtDisplay.Text = String.Empty
            txtDisplay.Text += intOne.ToString()
            obj.AddBtn = False
        End If

        If obj.SubBtn = True Then
            txtDisplay.Text = String.Empty
            txtDisplay.Text -= intOne.ToString()
            obj.SubBtn = False
        End If
    End Sub

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Question by:Keith1985
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3 Comments
 
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Accepted Solution

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cyberkiwi earned 50 total points
ID: 33697706
It is because while you can concatenate strings using +, you cannot take away using -

            txtDisplay.Text -= intOne.ToString()

You are trying to use -=?
Or is that a mistype?
0
 

Author Comment

by:Keith1985
ID: 33697845
Okay I see, so what I need to do is something like:

intResult -= intOne
txtDisplay.Text = intResult.ToString()

Is this correct?
0
 

Author Closing Comment

by:Keith1985
ID: 33701859
Problem solved.
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