バージョン

IsNull プロパティ

このクラス インスタンスが null 値を含むかどうかを返します。
シンタックス
'宣言
 
Public ReadOnly Property IsNull As Boolean
public bool IsNull {get;}

プロパティ値

このインスタンス クラスが null 値を含む場合は True、それ以外の場合は False。
使用例
Imports Infragistics.Shared
Imports Infragistics.Win
Imports Infragistics.Win.UltraWinGrid
Imports Infragistics.Win.CalcEngine
Imports Infragistics.Win.UltraWinCalcManager

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
        ' Ensure that the form contains an UltraCalcManager and two textboxes, 
        ' one named textBox1 and the other named textBox2.
        Dim calcSettings As CalcSettings = New CalcSettings()
        ' This formula will multiply the value of textBox2 by 2.
        calcSettings.Formula = "2 * [textBox2]"
        calcSettings.PropertyName = "Text"
        Me.UltraCalcManager1.SetCalcSettings(Me.TextBox1, calcSettings)

        calcSettings = New CalcSettings()
        calcSettings.PropertyName = "Text"
        ' Treat the values of the textBox2 as double. Text property of TextBox is
        ' a string type and since textBox2 is a source of value to a formula, indicate 
        ' to the calc-manager that the value should be treated as a double rather
        ' than as a string. 
        calcSettings.TreatAsType = GetType(Double)
        Me.UltraCalcManager1.SetCalcSettings(Me.TextBox2, calcSettings)
    End Sub

    Private Sub UltraCalcManager1_ParseValue(ByVal sender As Object, ByVal e As Infragistics.Win.UltraWinCalcManager.ParseValueEventArgs) Handles ultraCalcManager1.ParseValue
        ' ParseValue gets fired on all controls that are source of values in formulas.
        If e.Control Is Me.textBox2 Then
            ' Get the text of the textBox2.
            Dim text As String = Me.textBox2.Text

            If 0 = text.Length Then
                ' If the textbox is empty, then you can return an error. By default the 
                ' calc manager considers empty strings to be 0.
                e.Value = New UltraCalcValue(New UltraCalcErrorValue(UltraCalcErrorCode.Num, "Not a Number"))
            Else
                ' Otherwise parse the text to a double and return that as the value. 
                ' The calc manager by default uses InvariantCulture to parse text into
                ' numeric values. Typically you want to use the current culture to parse
                ' text into numeric values. ParseValue event is especially useful for that.
                e.Value = New UltraCalcValue(Double.Parse(text))
            End If

            e.Handled = True
        End If
    End Sub

    Private Sub UltraCalcManager1_FormatValue(ByVal sender As Object, ByVal e As Infragistics.Win.UltraWinCalcManager.FormatValueEventArgs) Handles ultraCalcManager1.FormatValue
        ' FormatValue gets fired on all controls that are target of formula evaluations.
        If e.Control Is Me.textBox1 Then
            If e.CalcValue.IsError Then
                ' There was an error in formula evaluation.
                e.Value = e.CalcValue.ToErrorValue().Message
            ElseIf e.CalcValue.IsDBNull Or e.CalcValue.IsNull Then
                ' Result is DBNull or Null.
                e.Value = "(NULL)"
            Else
                Dim doubleVal As Double
                If e.CalcValue.ToDouble(doubleVal) Then
                    ' ToDouble returns true if the value was a double.
                    e.Value = CType(doubleVal, Decimal).ToString("c")
                Else
                    ' Otherwise convert the value to a string using current culture.
                    e.Value = e.CalcValue.ToString(System.Globalization.CultureInfo.CurrentCulture)
                End If
            End If
        End If
    End Sub
using Infragistics.Shared;
using Infragistics.Win;
using Infragistics.Win.UltraWinGrid;
using System.Diagnostics;
using Infragistics.Win.CalcEngine;
using Infragistics.Win.UltraWinCalcManager;

		private void Form1_Load(object sender, System.EventArgs e)
		{
			// Ensure that the form contains an UltraCalcManager and two textboxes, 
			// one named textBox1 and the other named textBox2.
			CalcSettings calcSettings = new CalcSettings( );
			// This formula will multiply the value of textBox2 by 2.
			calcSettings.Formula = "2 * [//textBox2]";
			calcSettings.PropertyName = "Text";
			this.ultraCalcManager1.SetCalcSettings( this.textBox1, calcSettings );

			calcSettings = new CalcSettings( );
			calcSettings.PropertyName = "Text";
			// Treat the values of the textBox2 as double. Text property of TextBox is
			// a string type and since textBox2 is a source of value to a formula, indicate 
			// to the calc-manager that the value should be treated as a double rather
			// than as a string. 
			calcSettings.TreatAsType = typeof( double );
			this.ultraCalcManager1.SetCalcSettings( this.textBox2, calcSettings );
		}

		private void ultraCalcManager1_ParseValue(object sender, Infragistics.Win.UltraWinCalcManager.ParseValueEventArgs e)
		{
			// ParseValue gets fired on all controls that are source of values in formulas.
			if ( e.Control == this.textBox2 )
			{
				// Get the text of the textBox2.
				string text = this.textBox2.Text;
				
				if ( 0 == text.Length )
				{
					// If the textbox is empty, then you can return an error. By default the 
					// calc manager considers empty strings to be 0.
					e.Value = new UltraCalcValue( new UltraCalcErrorValue( UltraCalcErrorCode.Num, "Not a Number" ) );
				}
				else
				{
					// Otherwise parse the text to a double and return that as the value. 
					// The calc manager by default uses InvariantCulture to parse text into
					// numeric values. Typically you want to use the current culture to parse
					// text into numeric values. ParseValue event is especially useful for that.
					e.Value = new UltraCalcValue( double.Parse( text ) );
				}

				e.Handled = true;
			}
		}

		private void ultraCalcManager1_FormatValue(object sender, Infragistics.Win.UltraWinCalcManager.FormatValueEventArgs e)
		{
			// FormatValue gets fired on all controls that are target of formula evaluations.
			if ( e.Control == this.textBox1 )
			{
				if ( e.CalcValue.IsError )
				{
					// There was an error in formula evaluation.
					e.Value = e.CalcValue.ToErrorValue( ).Message;
				}
				else if ( e.CalcValue.IsDBNull || e.CalcValue.IsNull )
				{
					// Result is DBNull or Null.
					e.Value = "(NULL)";
				}
				else 
				{
					double doubleVal;
					if ( e.CalcValue.ToDouble( out doubleVal ) )
					{
						// ToDouble returns true if the value was a double.
						e.Value  = ((decimal)doubleVal).ToString( "c" );
					}
					else
					{
						// Otherwise convert the value to a string using current culture.
						e.Value = e.CalcValue.ToString( System.Globalization.CultureInfo.CurrentCulture );
					}
				}
			}
		}
参照