[bgile]

I am writing a program to calculate Fahrenheit to Celsius and Celsius to Fahrenheit.
I just can not get my math to work. thanks for any help.

Option Explicit On
Option Strict On
Option Infer Off


Public Class MainForm
	Private Sub CalcFahren(ByRef ftemp As Integer)
		Dim totalTemp As Decimal
		totalTemp = CDec(CDbl(TempTextBox.Text) * 9 / 5 + 32)
	End Sub
	Private Sub CalcCelsisus(ByRef ctemp As Integer)
		Dim cTotalTemp As Decimal
		cTotalTemp = CDec((CDbl(TempTextBox.Text) - 32) * 5 / 9)

	End Sub
	Private Sub exitButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles exitButton.Click
		Me.Close()
	End Sub
	Private Sub calcCelsButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles calcCelsButton.Click
		Dim temp As Decimal
		Call CalcCelsisus(CInt(temp))

		celsLabel.Text = temp.ToString("N2")

		TempTextBox.Focus()
		TempTextBox.SelectAll()

	End Sub

	Private Sub calcFehrenButton_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles calcFehrenButton.Click

		Dim secTemp As Decimal

		Call CalcFahren(CInt(secTemp))

		fahrenLabel.Text = secTemp.ToString("N2")

		TempTextBox.Focus()
		TempTextBox.SelectAll()

	End Sub
End Class

[JackOfAllTrades]

Off to VB.NET.

[mark.bottomley]

You are not getting the correct data into the Sub and you are not retiurning any result from the calculation.

' A function is a Sub that returns a result - it can be returned with either a Return statement, or the name of the Function can be used as the variable that will automatically be returned.
	Private Function CalcFahren(ByRef ftemp As Decimal) As Decimal
		CalcFahren= CDec(ftemp) * 9 / 5 + 32
		' alternate - "Return CDec(ftemp) * 9 / 5 + 32"
	End Function

' and call it with
Dim resultTemp As Decimal
resultTemp  = CalcFahren(CDec(TempTextBox.Text))
' now output it somewhere
...

[dzone41]

Starting with calcCelsButton.Click:
"temp" is not assigned a value before it is used, so an error will occur.
Suggest making CalcCelsisus a function and setting the value of temp to that function like:

temp = CalcCelsisus()

And the function

 ''''Watch out for the spelling, I have corrected it here
Private Function CalcCelsius() As Decimal
   Dim cTotalTemp As Decimal
   cTotalTemp = CDec((CDbl(TempTextBox.Text) - 32) * 5 / 9)
   Return cTotalTemp
End Function

Try that with the other button press and routine for calculating Fahrenheit.
Hope this helps



oops, sorry Mark, didn't see your reply

This post has been edited by dzone41: 10 November 2009 - 07:33 AM

[Shadar]

Your code is more complicated than it needs to be.
Take a look at the code below.

Public Class Form3

	Private Function CelciusToFahrenheit(ByVal Tc As Decimal) As Decimal
		Dim Tf As Decimal
		Tf = (9 / 5) * Tc + 32
		Return Tf
	End Function

	Private Function FahrenheitToCelcius(ByVal Tf As Decimal) As Decimal
		Dim tc As Decimal
		Tc = (5 / 9) * (Tf - 32)
		Return TC
	End Function

	Private Sub txtFahrenheit_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtFahrenheit.KeyUp
		If txtCelsius.Text <> String.Empty Then
			txtCelsius.Text = FahrenheitToCelcius(txtFahrenheit.Text)
		Else
			txtCelsius.Text = ""
		End If
	End Sub

	Private Sub txtCelsius_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles txtCelsius.KeyUp
		If txtCelsius.Text <> String.Empty Then
			txtFahrenheit.Text = CelciusToFahrenheit(txtCelsius.Text)
		Else
			txtFahrenheit.Text = ""
		End If
	End Sub
End Class