I have to create an application that calculates the number of wallpaper rolls to cover a wall. I also have to use one or more independent sub or function procedures. So far I have this but it keeps telling me I can't divide by zero.
'declare variables
Dim WallWidth As Integer 'width of wall
Dim WallHeight As Integer 'height of wall
Dim RollLength As Integer ' length of wallpaper roll
Dim RollWidth As Integer ' width of wallpaper roll
Dim areawall As Integer
Dim area As Integer
Dim NumofRoll As Integer 'number of rolls needed
Dim totroll As Integer

'Text box is numeric
If txtwidthwall.Text <> "" Then
'assign text box
If IsNumeric(txtwidth.Text) Then
WallWidth = Convert.ToInt32(txtwidth.Text)
ElseIf IsNumeric(txtheight.Text) Then
WallHeight = Convert.ToInt32(txtheight.Text)
ElseIf IsNumeric(txtlengthwall.Text) Then
RollLength = Convert.ToInt32(txtlengthwall.Text)
ElseIf IsNumeric(txtwidthwall.Text) Then
RollWidth = Convert.ToInt32(txtwidthwall.Text)

Else
MessageBox.Show("Please enter number.", _
"Wallpaper", MessageBoxButtons.OK, _
MessageBoxIcon.Information, _
MessageBoxDefaultButton.Button1)

End If
areawall = WallWidth * WallHeight
Call Arearoll(RollLength, RollWidth, Area)
totroll = areawall / area

End If
Me.lbltotal.Text = Convert.ToString(totroll)






End Sub
Private Sub Arearoll(ByVal length As Integer, ByVal width As Integer, ByRef area As String)
'calculates the number of rolls
area = length * width

You never put a value in your "area" variable, but you defined it as an integer. This will cause it to be equal to zero until otherwise stated. The "length" and "width" variables were never declared, or assigned a value, so your Sub does nothing. You can't divide by zero (at least not in VB). Thus areawall / area = nonsense.

Just from this glance, it seems like you're over complicating this task.

so if I don't do a separate sub function and just solve the area in the calculate sub would I put the area intger and change that to a string variable

totroll = areawall / area

instead

totroll = areawall / Val(area)

As long as area doesn't contain any other characters.

Why is it a string value anyway?

No I think that should work! Thanks so much!