Datagrid将字符串转换为Int

问题描述：

当我加起来为每一行摇动主菜和酒吧..ex。 12 + 12+ 12 toal to 121212

When i add up shakes entrees and barsfor each row now..ex. 12 + 12+ 12 the toal comes to 121212

myTable.Columns.Add("Shake /Cereal", GetType(String))
        myTable.Columns.Add("Entrees", GetType(String))
        myTable.Columns.Add("Bars", GetType(String))
        myTable.Columns.Add("Total", GetType(String))
        myTable.Columns("Total").Expression = "[Shake /Cereal] + Entrees + Bars"

Select Case e.ColumnIndex
           Case 5 To 7
               Dim myVal As Integer = 0
               Dim result As Boolean = Int32.TryParse(DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex).Value, myVal)
               If Not result Then
                   MessageBox.Show("Please enter a numeric value.", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
                   DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex).Value = String.Empty
               Else
                   'proper value! use myVal
               End If
           Case Else
       End Select

答

好的，在我回答问题之前，几点说明：

1）不良做法 - 如果某些部分代码被多次使用，则需要将其移至单独的程序或功能中

OK, before i answer the question, few notes:
1) bad practice - if some part of code is used more than once, you need to move it into separate procedure or function

If (e.ColumnIndex = 5) Then   ' Checking numeric value for Column 5 only
        'see code below
ElseIf (e.ColumnIndex = 6) Then   ' Checking numeric value for Column 6 only
        'see code below
ElseIf (e.ColumnIndex = 7) Then   ' Checking numeric value for Column 7 only
    'code which was used 2 times before
    '<-- start
    Dim value As String = DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex).Value.ToString()
    For Each c As Char In value
        If Not Char.IsDigit(c) Then
            MessageBox.Show("Please enter a numeric value.", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
            DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex).Value = String.Empty
            Exit Sub
        End If
'end -->
End if

2）不良做法 - 如果您想检查一系列列中的值，请使用：

2) bad practice - if you want to check value in a range of columns, use:

If (e.ColumnIndex=5) Or (e.ColumnIndex=6) Or (e.ColumnIndex=7) Then
'...do something...
Else
'...do something...
End If

或

 Select Case e.ColumnIndex
    Case 5, 6, 7
    '...do something...
    Case Else
    '...do something...
End Select

Select Case .... End Select [ ^ ]

3）不良做法 - 如果你想检查价值是否为数字，请不要将其转换为字符串而不要按标志检查，但请使用 Convert.To< TypeOfData> [ ^ ]或< TypeOfData> .Parse [ ^ ]或< TypeOfData> .TryParse [ ^ ]方法

更多关于解析数字字符串 [ ^ ]

最后，答案是：使用 TryParse 方法将错误输入替换为数值（例如 0 /零/）;）

Select Case .... End Select[^]

3) bad practice - if you want to check if value is numeric, do not convert it into string and do not check it sign by sign, but please use Convert.To<TypeOfData>[^] or <TypeOfData>.Parse[^] or <TypeOfData>.TryParse[^] method
More about Parsing Numeric Strings[^]

Finally, the answer is: using TryParse method replace wrong input into numeric value (for example to 0 /zero/) ;)

Private Sub DataGridView1_CellEndEdit(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView1.CellEndEdit

Select Case e.ColumnIndex
    Case 5 to 7
        Dim myVal AS Integer = 0
        Dim result As Boolean = Int32.TryParse(DataGridView1.Rows(e.RowIndex).Cells(e.ColumnIndex).Value,myVal)
        If not result Then 
             'convertion failed
        Else
             'proper value! use myVal
        End If
    Case else
        'do nothing
End Select

End Sub

[/ EDIT]

[/EDIT]

Private Sub DataGridView1_DataError(sender As Object, e As System.Windows.Forms.DataGridViewDataErrorEventArgs) Handles DataGridView1.DataError

       If MessageBox.Show("Please enter a numeric value only.", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Error) Then
           e.Cancel = True
       End If

   End Sub

Datagrid将字符串转换为Int

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