在System.Windows.Forms.DataGrid中設置double/float/decimal的精度

Question

如何設置保存System.Windows.Forms.DataGrid中double，float或decimal數據的數據列的精度？

對於DataGridView，例如有How to format a column with number decimal with max and min in DataGridView?。

我想0.0100000001顯示爲0.01，例如，這將是小數點後2位的精度。我想，以避免它們看起來像這樣，在float和double使用科學記數法：

我用來填充表的代碼是：

var table = new DataTable(); 
table.Columns.Add("double"); 
table.Columns.Add("float"); 
table.Columns.Add("decimal"); 
table.Columns[0].DataType = typeof(double); 
table.Columns[1].DataType = typeof(float); 
table.Columns[2].DataType = typeof(decimal); 
table.Rows.Add(new object[] { 0.00000000000423, 0.00000000000423, 0.00000000000423 }); 
dataGrid1.DataSource = table; 

注：我知道的DataGrid已經過時，但我正在處理遺留代碼，請不要評論告訴我使用DataGridView - 它不會幫助我。

Answer 1

請查找更新ANS

var table = new DataTable(); 
table.Columns.Add("double"); 
table.Columns.Add("float"); 
table.Columns.Add("decimal"); 
dataGrid1.DataSource = table; 
table.Columns[0].DataType = typeof(double); 
table.Columns[1].DataType = typeof(float); 
table.Columns[2].DataType = typeof(decimal); 
table.Rows.Add(new object[] { 0.00000000000423, 0.00000000000423, 0.00000000000423 }); 

總是先綁定的DataGrid然後格式化列

Answer 2

我來源於@stuartd評論我的解決方案。我需要爲DataGrid設置Format列of the current table style。

/// <summary> 
/// Getting and setting the column widths of a DataGrid is not easy at all. 
/// This helper class handles it, including saving and restoring from a string. 
/// </summary> 
static class DataGridColumnWidthExtensions 
{ 
    /// Get the current table style. 
    public static DataGridTableStyle GetCurrentTableStyle(this DataGrid grid) 
    { 
     // DataGrid holds the current grid table style into a private field called myGridTable. 
     // The field points to the "default" table style even if TableStyles is empty. The 
     // default table style is also private/internal. 
     // See https://stackoverflow.com/a/39832554/492336 and 
     // https://referencesource.microsoft.com/#System.Windows.Forms/winforms/Managed/System/WinForms/DataGrid.cs,211. 
     FieldInfo[] fields = grid.GetType().GetFields(
        BindingFlags.NonPublic | 
        BindingFlags.Instance); 

     return (DataGridTableStyle)fields.First(item => item.Name == "myGridTable").GetValue(grid); 
    } 
} 

然後我們就可以遍歷GridColumnStyles並設置格式屬性爲每個數字列：

var tableStyle = dataGrid1.GetCurrentTableStyle(); 
for (int ii = 0; ii < table.Columns.Count; ii++) 
{ 
    var columnStyle = tableStyle.GridColumnStyles[ii] as DataGridTextBoxColumn; 
    if (columnStyle == null) 
    { 
     // DataGridTextBoxColumn inherits DataGridColumnStyle but in theory 
     // a column might be of some other type deriving from DataGridColumnStyle. 
     continue; 
    } 

    var columnType = table.Columns[ii].DataType; 
    if (columnType != typeof(double) && columnType != typeof(float) && columnType != typeof(decimal)) 
    { 
     // We set the format only for numeric columns. 
     continue; 
    } 

    // 2 digits after the decimal mark. 
    columnStyle.Format = "N2"; 
}