vb.net - 在VB.NET中修剪字符串的最后一个“，”分隔符

Question

这是我的代码：

With ad.Tables(2)
    For i As Integer = 0 To .Rows.Count - 1
        If .Rows(i)("name") & "" <> "" Then
            temp &= .Rows(i)("name") & ", "
        End If
    Next
End With
temp = temp.Trim(",")
testing &= "&Name=" & temp & vbCrLf

这是在字符串的末尾得到一个逗号。但如果我这样做

temp = temp.Trim.Trim(",")

所有逗号都被删除。

如何保留所有逗号并仅删除最后一个逗号？

Answer 1

temp = temp.TrimEnd(CChar(","))

那会做到的，我认为这是最简单的方法。

Answer 2

temp = temp.Trim().Substring(0, temp.Length - 1)

或者

temp = temp.Trim().Remove(temp.Length - 1)

Answer 3

如果在循环中设置分隔符，则可以避免使用 Trim/extra 字符

Dim delimiter as string = ""
For i As Integer = 0 To .Rows.Count - 1
   If .Rows(i)("name") & "" <> "" Then
      temp &= delimiter & .Rows(i)("name")
      delimiter = ","
   End If
Next

Answer 4

该Trim()函数有一个Char()（静态字符数组）参数，您不需要Char显式传递。

' VB.Net Version
", Hello ^_^ ^_^ ,,, , ,,   ,, ,".Trim({" "c, ","c})

//C# version
", Hello ^_^ ^_^ ,,, , ,,   ,, ,".Trim({' ', ','})

会产生输出

"Hello ^_^ ^_^"

多参数.Trim()从字符串的开头和结尾删除指定的字符。如果您只想修剪开头或结尾，请分别使用.TrimStart()或.TrimEnd()。

Answer 5

这有效：

dim AlarmStr as string="aaa , bbb , ccc ,  "
AlarmStr = AlarmStr.Remove(AlarmStr.LastIndexOf(","))

Answer 6

我想知道，基于 OP 的代码示例，没有人建议使用String.Join或构建输出StringBuilder

Dim names As New List(Of String)
With ad.Tables(2)
    For i As Integer = 0 To .Rows.Count - 1
        ' DataRow("columnName").ToString() returns value or empty string if value is DbNull
        If .Rows(i)("name").ToString() <> "" Then
           names.Add(.Rows(i)("name"))
        End If
    Next
End With

Dim temp As String = String.Join(", ", names)
testing &= "&Name=" & temp & vbCrLf

使用 LINQ 和DataRow扩展方法.Field(Of T)代码会看起来更简单

Dim names = ad.Tables(2).
    AsEnumerable().
    Select(row => row.Field<String>("name")).
    Where(name => String.IsNullOrEmpty(name) = False)

Dim temp As String = String.Join(", ", names)
testing &= "&Name=" & temp & vbCrLf

如果您走得更远，您可以（应该）StringBuilder用于构建字符串并使用Aggregate方法从集合中构建字符串

Answer 7

在添加最后一个逗号之前检查循环是否完成。＃清洁器

While dr.Read
   For c As Integer = 0 To dr.FieldCount - 1
       s.Append(dr(c).ToString.Trim)

       'This line checks if the loop is ending before adding a comma           
       If (c < dr.FieldCount - 1) Then s.Append(",")

   Next
   s.Append(vbCrLf)
End While

Answer 8

我知道这有点奇怪，但我发现这对我有用：

视觉基础：

每次：mystring = "今天，我爱出门，, , , ,"（少于五个逗号和空格）

mystring.Trim.TrimEnd(",").Trim.TrimEnd(",").Trim.TrimEnd(",").Trim.TrimEnd(",").Trim.TrimEnd(",")

Answer 9

temp = temp.TrimEnd()

这会从字符串中修剪尾随空格。