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Dobrý večer, pokouším se udělat kalkulačku sčítání odčítaní atd. funguje.Problém nastane když zadám např. číslo 0.5 + a chci zadat další číslo tak to vyhodí chybu.

Zde je celej kod:

Public Class Form1
    Dim FirstNumber As Long
    Dim Operation As String
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "1"
        Else
            TextBox1.Text = TextBox1.Text & "1"
        End If
    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "2"
        Else
            TextBox1.Text = TextBox1.Text & "2"
        End If

    End Sub

    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "3"
        Else
            TextBox1.Text = TextBox1.Text & "3"
        End If

    End Sub

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click

        If TextBox1.Text = "0" Then
            TextBox1.Text = "4"
        Else
            TextBox1.Text = TextBox1.Text & "4"
        End If
    End Sub

    Private Sub Button5_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button5.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "5"
        Else
            TextBox1.Text = TextBox1.Text & "5"
        End If
    End Sub

    Private Sub Button6_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button6.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "6"
        Else
            TextBox1.Text = TextBox1.Text & "6"
        End If
    End Sub

    Private Sub Button7_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button7.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "7"
        Else
            TextBox1.Text = TextBox1.Text & "7"
        End If
    End Sub

    Private Sub Button8_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button8.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "8"
        Else
            TextBox1.Text = TextBox1.Text & "8"
        End If
    End Sub

    Private Sub Button9_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button9.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "9"
        Else
            TextBox1.Text = TextBox1.Text & "9"
        End If
    End Sub

    Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button11.Click
        TextBox1.Text = TextBox1.Text & "."
    End Sub

    Private Sub Button10_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button10.Click
        If TextBox1.Text = "0" Then
            TextBox1.Text = "0"
        Else
            TextBox1.Text = TextBox1.Text & "0"
        End If
    End Sub

    Private Sub Button13_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button13.Click
        TextBox1.Text = "0"
    End Sub

    Private Sub Button16_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button16.Click
        FirstNumber = TextBox1.Text
        TextBox1.Text = "0"
        Operation = "+"
    End Sub

    Private Sub Button14_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button14.Click
        FirstNumber = TextBox1.Text
        TextBox1.Text = "0"
        Operation = "-"
    End Sub

    Private Sub Button15_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button15.Click
        FirstNumber = TextBox1.Text
        TextBox1.Text = "0"
        Operation = "*"

    End Sub

    Private Sub Button17_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button17.Click
        FirstNumber = TextBox1.Text
        TextBox1.Text = "0"
        Operation = "/"
    End Sub

    Private Sub Button12_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button12.Click
        Dim SecondNumber As Long
        Dim Result As Long
        SecondNumber = TextBox1.Text
        If Operation = "+" Then
            Result = FirstNumber + SecondNumber
        ElseIf Operation = "-" Then
            Result = FirstNumber - SecondNumber
        ElseIf Operation = "*" Then
            Result = FirstNumber * SecondNumber
        ElseIf Operation = "/" Then
            Result = FirstNumber / SecondNumber
        End If
        FirstNumber = Result
        TextBox1.Text = Result
    End Sub
End Class

a zde v tomto řádku při sčítání vyhodí chybu:

  Private Sub Button16_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button16.Click
        FirstNumber = TextBox1.Text
        TextBox1.Text = "0"
        Operation = "+"
    End Sub

Děkuji za každou pomoc

FirstNumber definované jako Long číslo chcete naplnit textem - přidejte konverzi obsahu TexBoxu:

 FirstNumber = CLng(TextBox1.Text)

1) Proměná FirstNumber je typu Long, což je celočíselný datový typ, nemůže proto obsahovat hodnotu 0.5. Řešením je použít Single nebo Double.

2)

FirstNumber = TextBox1.Text

Konverze textu na číslo proběhne podle místního nastavení (CultureInfo). Na počítači s českým nastavením je tedy nutné použít desetinou čárku místo desetiné tečky.

Poznámka: Desetinou tečku lze také použít, ale je potřeba provést konverzi následujícím způsobem (např. na typ Double):

    FirstNumber = Convert.ToDouble(TextBox1.Text, System.Globalization.CultureInfo.InvariantCulture)