将数字的位数相加，直到得到一位数

Question

这段代码有效，例如，如果我有一个号码14，它将给出1+4=5 但如果我有，例如，78，结果将是7+8=15，我希望显示1+5=6，所以它将是6，而不是15。那我该如何解决呢？

   Dim lines As String() = originalString.Split(CChar(Environment.NewLine))

            For Each line As String In lines

                Dim lineSum As String = Nothing

                For Each numberChar As Char In line
                    If Asc(numberChar) >= 48 AndAlso Asc(numberChar) < 58 Then  'making sure this is a number and nothing else
                        lineSum += Asc(numberChar) - 48 'using the ascii chart to determine the value tu add
                    End If
                Next

                If results <> "" Then results &= vbNewLine
                results &= lineSum.ToString

            Next

Answer 1

您可以使用此递归方法：

Public Shared Function GetSum(number As String, Optional maxDigits As Int32? = Nothing) As Int32?
    If Not number.All(AddressOf Char.IsDigit) Then Return Nothing
    Dim sum = number.Sum(AddressOf Char.GetNumericValue)
    If(Not maxDigits.HasValue Orelse sum.ToString().Length <= maxDigits) Then Return sum
    Return GetSum(sum.ToString(), maxDigits)
End Function

使用您的样品：

Sub Main
    Dim sum1 As int32 = GetSum("14", 1)
    Dim sum2 As int32 = GetSum("78", 1)
    Console.WriteLine("Sum of 14: " & sum1)
    Console.WriteLine("Sum of 78: " & sum2)
End Sub

输出：

Sum of 14: 5
Sum of 78: 6