ok, so I am not sure what I'm doing wrong. I wrote this code for an assignment and it is giving me this error: Conversion from string "" to type 'Double' is not valid...on this line r = CDbl(txtResthr.Text)
Here is the full program:
Public Class Form1
Private Sub txtAge_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtAge.TextChanged
End Sub
Private Sub txtResthr_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtResthr.TextChanged
End Sub
Private Sub btnCompute_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCompute.Click
Dim a, r As Double
Dim trainingheartrate As Double
a = CDbl(txtAge.Text)
r = CDbl(txtResthr.Text)
trainingheartrate = 0.7 * (220 - a) + 0.3 * r
trainingheartrate = Math.Round(trainingheartrate, 1)
txtTrainhr.Text = "Your THR is" & trainingheartrate & " beats per minute"
End Sub
Private Sub txtTrainhr_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtTrainhr.TextChanged
End Sub
End Class
Can someone point me in the right direction? Thanks!!
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