Nullable<T>.ToString 方法

定义

返回当前 Nullable<T> 对象的值的文本表示形式。Returns the text representation of the value of the current Nullable<T> object.

public:
 override System::String ^ ToString();
public override string ToString ();
public override string? ToString ();
override this.ToString : unit -> string
Public Overrides Function ToString () As String

返回

String

如果 Nullable<T> 属性为 HasValue,则是当前 true 对象的值的文本表示形式;如果 HasValue 属性为 false,则是一个空字符串 ("")。The text representation of the value of the current Nullable<T> object if the HasValue property is true, or an empty string ("") if the HasValue property is false.

示例

下面的代码示例显示当前对象的值 Nullable<T>The following code example displays the value of the current Nullable<T> object.

// This code example demonstrates the
// Nullable<T>.ToString method.

using System;

class Sample
{
    public static void Main()
    {
    DateTime? nullableDate;

// Display the current date and time.
    nullableDate = DateTime.Now;
    Display("1)", nullableDate);

// Assign null (Nothing in Visual Basic) to nullableDate, then
// display its value.
    nullableDate = null;
    Display("2)", nullableDate);
    }

// Display the text representation of a nullable DateTime.
    public static void Display(string title, DateTime? dspDT)
    {
    string msg = dspDT.ToString();

    Console.Write("{0} ", title);
    if (String.IsNullOrEmpty(msg))
        Console.WriteLine("The nullable DateTime has no defined value.");
    else
        Console.WriteLine("The current date and time is {0}.", msg);
    }
}

/*
This code example produces the following results:

1) The current date and time is 4/19/2005 8:28:14 PM.
2) The nullable DateTime has no defined value.

*/
' This code example demonstrates the 
' Nullable<T>.ToString method.

Class Sample
    Public Shared Sub Main() 
        Dim nullableDate As Nullable(Of DateTime)
    ' Display the current date and time.
        nullableDate = DateTime.Now
        Display("1)", nullableDate)
        
    ' Assign null (Nothing in Visual Basic) to nullableDate, then 
    ' display its value.
        nullableDate = Nothing
        Display("2)", nullableDate)
    End Sub

    '  Display the text representation of a nullable DateTime.
    Public Shared Sub Display(ByVal title As String, _
                              ByVal dspDT As Nullable(Of DateTime))
        Dim msg As String = dspDT.ToString()

        Console.Write("{0} ", title)
        If String.IsNullOrEmpty(msg) Then
            Console.WriteLine("The nullable DateTime has no defined value.")
        Else
            Console.WriteLine("The current date and time is {0}.", msg)
        End If
    End Sub
End Class

'This code example produces the following results:
'
'1) The current date and time is 4/19/2005 8:28:14 PM.
'2) The nullable DateTime has no defined value.
'

注解

ToString属性返回通过调用属性返回的对象的属性而生成的字符串 ToString ValueThe ToString property returns the string yielded by calling the ToString property of the object returned by the Value property.

适用于