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Trying to SUM listbox items, but getting "Conversion from type 'ListItem' to type 'String' is not valid". Need someone to check code.

Posted on 2013-05-20
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Last Modified: 2013-05-21
Hello,
can someone please advise what I'm doing wrong. I have try many solutions, but just cannot get out from error like:
"Conversion from type 'ListItem' to type 'String' is not valid", or
Conversion from type 'ListItem' to type 'Double' is not valid, or
Conversion from type 'ListItem' to type 'Integer' is not valid, etc

Dim result As Double = Math.Round((TextBoxA.Text + TextBoxB.Text, 1)
        MsgBox(result)
        Dim Pcs As String = result * TextBoxC.Text
        MsgBox(Pcs)
        ListBox1.Items.Add(Pcs)
        Dim sum As Double
        For Each item As String In ListBox1.Items
            sum += Double.Parse(item)
        Next

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Thanks in advance for hlep!
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Question by:dejandejanovic
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3 Comments
 
LVL 42

Expert Comment

by:sedgwick
ID: 39182638
Dim result As Double = Math.Round((TextBoxA.Text + TextBoxB.Text, 1)
        MsgBox(result)
        Dim Pcs As String = result * TextBoxC.Text
        MsgBox(Pcs)
        ListBox1.Items.Add(Pcs)
        Dim sum As Double
        For Each item As Object In ListBox1.Items
            sum += Double.TryParse(item.ToString())
        Next

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0
 
LVL 42

Accepted Solution

by:
sedgwick earned 2000 total points
ID: 39182646
better yet with TryParse to avoid exception:
Dim result As Double = Math.Round((TextBoxA.Text + TextBoxB.Text, 1)
        MsgBox(result)
        Dim Pcs As String = result * TextBoxC.Text
        MsgBox(Pcs)
        ListBox1.Items.Add(Pcs)
        Dim sum As Double
        Dim number As Double
        For Each item As Object In ListBox1.Items
            if (Double.TryParse(item.ToString(), number)) then
                sum += number
        else
                'parsing failed
        end if
        Next

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0
 

Author Closing Comment

by:dejandejanovic
ID: 39183887
Works perfect! Thanks.
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