How to: Programmatically store and retrieve date values in Excel ranges

Článek
02/02/2017

Applies to: Visual Studio Visual Studio for Mac

Note

This article applies to Visual Studio 2017. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here

You can store and retrieve values in a NamedRange control or a native Excel range object.

Applies to: The information in this topic applies to document-level projects and VSTO Add-in projects for Excel. For more information, see Features available by Office application and project type.

If you store a date value that falls on or after 1/1/1900 in a range using Office development tools in Visual Studio, it is stored in OLE Automation (OA) format. You must use the FromOADate method to retrieve the value of OLE Automation (OA) dates. If the date is earlier than 1/1/1900, it is stored as a string.

Note

Excel dates differ from OLE Automation dates for the first two months of 1900. There are also differences if the 1904 date system option is checked. The code examples below do not address these differences.

Use a NamedRange control

This example is for document-level customizations. The following code must be placed in a sheet class, not in the ThisWorkbook class.

To store a date value in a named range

Create a NamedRange control at cell A1.

Microsoft.Office.Tools.Excel.NamedRange NamedRange1 =
    this.Controls.AddNamedRange(this.get_Range("A1"), "NamedRange1");

Dim NamedRange1 As Microsoft.Office.Tools.Excel.NamedRange = _
    Me.Controls.AddNamedRange(Me.Range("A1"), "NamedRange1")

Set today's date as the value for NamedRange1.

DateTime dt = DateTime.Now;
NamedRange1.Value2 = dt;

Dim dt As DateTime = DateTime.Now
NamedRange1.Value2 = dt

To retrieve a date value from a named range

Retrieve the date value from NamedRange1.

object value = NamedRange1.Value2;

if (value != null)
{
    if (value is double)
    {
        dt = DateTime.FromOADate((double)value);
    }
    else
    {
        DateTime.TryParse((string)value, out dt);
    }
}
MessageBox.Show(dt.ToString());

Dim value As Object = NamedRange1.Value2

If Not value Is Nothing Then
    If TypeOf value Is Double Then
        dt = DateTime.FromOADate(CType(value, Double))
    Else
        DateTime.TryParse(CType(value, String), dt)
    End If
End If

MessageBox.Show(dt.ToString())

Use native Excel ranges

To store a date value in a native Excel range object

Create a Range that represents cell A1.

Excel.Range rng = this.Application.get_Range("A1");

Dim rng As Excel.Range = Me.Application.Range("A1")

Set today's date as the value for rng.

DateTime dt = DateTime.Now;
rng.Value2 = dt;

Dim dt As DateTime = DateTime.Now
rng.Value2 = dt

To retrieve a date value from a native Excel range object

Retrieve the date value from rng.

object value = rng.Value2;

if (value != null)
{
    if (value is double)
    {
        dt = DateTime.FromOADate((double)value);
    }
    else
    {
        DateTime.TryParse((string)value, out dt);
    }
}
System.Windows.Forms.MessageBox.Show(dt.ToString());

Dim value As Object = rng.Value2

If Not value Is Nothing Then
    If TypeOf value Is Double Then
        dt = DateTime.FromOADate(CType(value, Double))
    Else
        DateTime.TryParse(CType(value, String), dt)
    End If
End If
System.Windows.Forms.MessageBox.Show(dt.ToString())

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