Function '<procedurename>' doesn't return a value on all code paths. Are you m,-CodePudding

Consider :

Private Function isAvailableQuantity() As Boolean
    Try
        sqL = "SELECT StocksOnHand FROM ITEM WHERE ItemNo = " & Val(txtSearch.Text) & ""
        ConnDB()
        cmd = New OleDbCommand(sqL, conn)
        dr = cmd.ExecuteReader(CommandBehavior.CloseConnection)


        If dr.Read = True Then

            If Val(txtQuantity.Text) <= dr(0) Then
                isAvailableQuantity = True
            Else
                MsgBox("Insuficient stocks", MsgBoxStyle.Critical, "Validate Stocks")
                txtSearch.Clear()
            End If
        End If
    Catch ex As Exception
        MsgBox(ex.Message)


    Finally
        cmd.Dispose()
        conn.Close()
    End Try

End Function

I don't know what to do. The older version visual studio doesn't get this error. i am using vs 2022 right now and it seems to have an error on the contrary vs 2010 doesn't

CodePudding user response：

In VB.NET, a Function is a method that returns a value and a Sub is a method that doesn't return a value. If your method doesn't need to return anything, use a Sub, e.g.

Private Sub DoSomething()
    'Do some stuff here.
End Sub

If you do use a Function then there are two ways to return a value. The bad way is to assign a value to the implicit local variable that is named after the method, e.g.

Private Function DoSomething() As Boolean
    'Do some stuff here.

    DoSomething = True
End Function

That way basically only exists to support upgraded VB6 code. If your teacher is showing you that then they are obviously an old VB6 developer who hasn't actually learned VB.NET properly. The good way to return a value is with an explicit Return statement, e.g.

Private Function DoSomething() As Boolean
    'Do some stuff here.

    Return True
End Function

If there are multiple paths that execution could take through your code, you need to make sure that a value is returned on all of them. As an example, this code does not do that:

Private Function DoSomething() As Boolean
    If Date.Now.DayOfWeek = DayOfWeek.Monday Then
        Return True
    End If
End Function

That will return True on Mondays but it doesn't return anything on other days. In this specific case, one fix would be this:

Private Function DoSomething() As Boolean
    If Date.Now.DayOfWeek = DayOfWeek.Monday Then
        Return True
    End If

    Return False
End Function

If you are going to use the bad way to return a value and you want to return a particular value on all but one code path then the logical thing to do is to set the return value at the start to the default and then only change it in that one place, e.g.

Private Function DoSomething() As Boolean
    DoSomething = False

    If Date.Now.DayOfWeek = DayOfWeek.Monday Then
        DoSomething = True
    End If
End Function

That last example is the easiest (although not best) fix for your scenario.