Convert.ToDateTime 方法

参考

定义

命名空间:: System

程序集:: System.Runtime.dll

程序集:: System.Runtime.Extensions.dll

程序集:: mscorlib.dll

程序集:: netstandard.dll

重要

一些信息与预发行产品相关，相应产品在发行之前可能会进行重大修改。对于此处提供的信息，Microsoft 不作任何明示或暗示的担保。

将指定的值转换为 DateTime 值。

重载

ToDateTime(Single)	调用此方法始终引发 InvalidCastException。
ToDateTime(String)	将日期和时间的指定字符串表示形式转换为等效的日期和时间值。
ToDateTime(UInt16)	调用此方法始终引发 InvalidCastException。
ToDateTime(String, IFormatProvider)	使用指定的区域性特定格式设置信息，将数字的指定字符串表示形式转换为等效的日期和时间。
ToDateTime(UInt64)	调用此方法始终引发 InvalidCastException。
ToDateTime(Object, IFormatProvider)	使用指定的区域性特定格式设置信息将指定对象的值转换为 DateTime 对象。
ToDateTime(SByte)	调用此方法始终引发 InvalidCastException。
ToDateTime(UInt32)	调用此方法始终引发 InvalidCastException。
ToDateTime(Object)	将指定对象的值转换为 DateTime 对象。
ToDateTime(Int16)	调用此方法始终引发 InvalidCastException。
ToDateTime(Int32)	调用此方法始终引发 InvalidCastException。
ToDateTime(Int64)	调用此方法始终引发 InvalidCastException。
ToDateTime(Double)	调用此方法始终引发 InvalidCastException。
ToDateTime(Decimal)	调用此方法始终引发 InvalidCastException。
ToDateTime(DateTime)	返回指定的 DateTime 对象；不执行任何实际的转换。
ToDateTime(Char)	调用此方法始终引发 InvalidCastException。
ToDateTime(Byte)	调用此方法始终引发 InvalidCastException。
ToDateTime(Boolean)	调用此方法始终引发 InvalidCastException。

ToDateTime(Single)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(float value);

public static DateTime ToDateTime (float value);

static member ToDateTime : single -> DateTime

Public Shared Function ToDateTime (value As Single) As DateTime

参数

value: Single

要转换的单精度浮点值。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

另请参阅

Single

适用于

ToDateTime(String)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

将日期和时间的指定字符串表示形式转换为等效的日期和时间值。

public:
 static DateTime ToDateTime(System::String ^ value);

public static DateTime ToDateTime (string value);

public static DateTime ToDateTime (string? value);

static member ToDateTime : string -> DateTime

Public Shared Function ToDateTime (value As String) As DateTime

参数

value: String

日期和时间的字符串表示形式。

DateTime

等效于的值的 value日期和时间，或者 DateTime.MinValue 的日期和时间等效项（如果 value 为 null）。

例外

FormatException

value 不是格式正确的日期和时间字符串。

示例

以下示例使用 ToDateTime 方法将日期和时间的各种字符串表示形式转换为 DateTime 值。

using System;

public class ConversionToDateTime
{
   public static void Main()
   {
      string dateString = null;

      // Convert a null string.
      ConvertToDateTime(dateString);

      // Convert an empty string.
      dateString = String.Empty;
      ConvertToDateTime(dateString);

      // Convert a non-date string.
      dateString = "not a date";
      ConvertToDateTime(dateString);

      // Try to convert various date strings.
      dateString = "05/01/1996";
      ConvertToDateTime(dateString);
      dateString = "Tue Apr 28, 2009";
      ConvertToDateTime(dateString);
      dateString = "Wed Apr 28, 2009";
      ConvertToDateTime(dateString);
      dateString = "06 July 2008 7:32:47 AM";
      ConvertToDateTime(dateString);
      dateString = "17:32:47.003";
      ConvertToDateTime(dateString);
      // Convert a string returned by DateTime.ToString("R").
      dateString = "Sat, 10 May 2008 14:32:17 GMT";
      ConvertToDateTime(dateString);
      // Convert a string returned by DateTime.ToString("o").
      dateString = "2009-05-01T07:54:59.9843750-04:00";
      ConvertToDateTime(dateString);
   }

   private static void ConvertToDateTime(string value)
   {
      DateTime convertedDate;
      try {
         convertedDate = Convert.ToDateTime(value);
         Console.WriteLine("'{0}' converts to {1} {2} time.",
                           value, convertedDate,
                           convertedDate.Kind.ToString());
      }
      catch (FormatException) {
         Console.WriteLine("'{0}' is not in the proper format.", value);
      }
   }
}
// The example displays the following output:
//    '' converts to 1/1/0001 12:00:00 AM Unspecified time.
//    '' is not in the proper format.
//    'not a date' is not in the proper format.
//    '05/01/1996' converts to 5/1/1996 12:00:00 AM Unspecified time.
//    'Tue Apr 28, 2009' converts to 4/28/2009 12:00:00 AM Unspecified time.
//    'Wed Apr 28, 2009' is not in the proper format.
//    '06 July 2008 7:32:47 AM' converts to 7/6/2008 7:32:47 AM Unspecified time.
//    '17:32:47.003' converts to 5/30/2008 5:32:47 PM Unspecified time.
//    'Sat, 10 May 2008 14:32:17 GMT' converts to 5/10/2008 7:32:17 AM Local time.
//    '2009-05-01T07:54:59.9843750-04:00' converts to 5/1/2009 4:54:59 AM Local time.

open System

let convertToDateTime (value: string) =
    try
        let convertedDate = Convert.ToDateTime value
        printfn $"'{value}' converts to {convertedDate} {convertedDate.Kind} time."
    with :?FormatException ->
        printfn $"'{value}' is not in the proper format."

[<EntryPoint>]
let main _ =
    let dateString = null

    // Convert a null string.
    convertToDateTime dateString

    // Convert an empty string.
    let dateString = String.Empty
    convertToDateTime dateString

    // Convert a non-date string.
    let dateString = "not a date"
    convertToDateTime dateString

    // Try to convert various date strings.
    let dateString = "05/01/1996"
    convertToDateTime dateString
    let dateString = "Tue Apr 28, 2009"
    convertToDateTime dateString
    let dateString = "Wed Apr 28, 2009"
    convertToDateTime dateString
    let dateString = "06 July 2008 7:32:47 AM"
    convertToDateTime dateString
    let dateString = "17:32:47.003"
    convertToDateTime dateString
    // Convert a string returned by DateTime.ToString("R").
    let dateString = "Sat, 10 May 2008 14:32:17 GMT"
    convertToDateTime dateString
    // Convert a string returned by DateTime.ToString("o").
    let dateString = "2009-05-01T07:54:59.9843750-04:00"
    convertToDateTime dateString

    0

// The example displays the following output:
//    '' converts to 1/1/0001 12:00:00 AM Unspecified time.
//    '' is not in the proper format.
//    'not a date' is not in the proper format.
//    '05/01/1996' converts to 5/1/1996 12:00:00 AM Unspecified time.
//    'Tue Apr 28, 2009' converts to 4/28/2009 12:00:00 AM Unspecified time.
//    'Wed Apr 28, 2009' is not in the proper format.
//    '06 July 2008 7:32:47 AM' converts to 7/6/2008 7:32:47 AM Unspecified time.
//    '17:32:47.003' converts to 5/30/2008 5:32:47 PM Unspecified time.
//    'Sat, 10 May 2008 14:32:17 GMT' converts to 5/10/2008 7:32:17 AM Local time.
//    '2009-05-01T07:54:59.9843750-04:00' converts to 5/1/2009 4:54:59 AM Local time.

Module ConversionToDateTime
   Public Sub Main()
      Dim dateString As String = Nothing
      
      ' Convert a null string.
      ConvertToDateTime(dateString)
      
      ' Convert an empty string.
      dateString = String.Empty
      ConvertToDateTime(dateString)
      
      ' Convert a non-date string.
      dateString = "not a date"
      ConvertToDateTime(dateString)
      
      ' Try to convert various date strings.
      dateString = "05/01/1996"
      ConvertToDateTime(dateString)
      dateString = "Tue Apr 28, 2009"
      ConvertToDateTime(dateString)
      dateString = "Wed Apr 28, 2009"
      ConvertToDateTime(dateString)
      dateString = "06 July 2008 7:32:47 AM"
      ConvertToDateTime(dateString)
      dateString = "17:32:47.003"
      ConvertToDateTime(dateString)
      ' Convert a string returned by DateTime.ToString("R").
      dateString = "Sat, 10 May 2008 14:32:17 GMT"
      ConvertToDateTime(dateString)
      ' Convert a string returned by DateTime.ToString("o")
      dateString = "2009-05-01T07:54:59.9843750-04:00"
      ConvertToDateTime(dateString)
   End Sub
   
   Private Sub ConvertToDateTime(value As String)
      Dim convertedDate As Date
      Try
         convertedDate = Convert.ToDateTime(value)
         Console.WriteLine("'{0}' converts to {1}.", value, convertedDate)
      Catch e As FormatException
         Console.WriteLine("'{0}' is not in the proper format.", value)
      End Try
   End Sub
End Module
' The example displays the following output:
'    '' converts to 1/1/0001 12:00:00 AM.
'    '' is not in the proper format.
'    'not a date' is not in the proper format.
'    '05/01/1996' converts to 5/1/1996 12:00:00 AM.
'    'Tue Apr 28, 2009' converts to 4/28/2009 12:00:00 AM.
'    'Wed Apr 28, 2009' is not in the proper format.
'    '06 July 2008 7:32:47 AM' converts to 7/6/2008 7:32:47 AM.
'    '17:32:47.003' converts to 5/30/2008 5:32:47 PM.
'    'Sat, 10 May 2008 14:32:17 GMT' converts to 5/10/2008 7:32:17 AM.
'    '2009-05-01T07:54:59.9843750-04:00' converts to 5/1/2009 4:54:59 AM.

注解

如果 value 不是 null，则返回值是使用针对当前区域性初始化的对象中的DateTimeFormatInfo格式设置信息调用 DateTime.Parse 方法value的结果。参数 value 必须包含主题中所述 DateTimeFormatInfo 格式之一的日期和时间的表示形式。如果 value 为 null，则此方法返回 DateTime.MinValue。

此方法尝试完全分析 value 并避免引发 FormatException。它用当前日期完成缺少的月份、日和年信息。如果 value 仅包含日期且不包含时间，则此方法假定时间为午夜。中 value 任何前导、内部或尾随空格字符将被忽略。

如果希望在转换失败时不处理异常，可以改为调用 DateTime.TryParse 方法。它返回一个 Boolean 值，该值指示转换是成功还是失败。

另请参阅

适用于

ToDateTime(UInt16)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

重要

此 API 不符合 CLS。

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(System::UInt16 value);

[System.CLSCompliant(false)]
public static DateTime ToDateTime (ushort value);

[<System.CLSCompliant(false)>]
static member ToDateTime : uint16 -> DateTime

Public Shared Function ToDateTime (value As UShort) As DateTime

参数

value: UInt16

要转换的 16 位无符号整数。

DateTime

不支持此转换。不返回任何值。

属性: CLSCompliantAttribute

例外

InvalidCastException

不支持此转换。

另请参阅

UInt16

适用于

ToDateTime(String, IFormatProvider)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

使用指定的区域性特定格式设置信息，将数字的指定字符串表示形式转换为等效的日期和时间。

public:
 static DateTime ToDateTime(System::String ^ value, IFormatProvider ^ provider);

public static DateTime ToDateTime (string value, IFormatProvider provider);

public static DateTime ToDateTime (string? value, IFormatProvider? provider);

static member ToDateTime : string * IFormatProvider -> DateTime

Public Shared Function ToDateTime (value As String, provider As IFormatProvider) As DateTime

参数

value: String

包含要转换的日期和时间的字符串。

provider: IFormatProvider

一个提供区域性特定的格式设置信息的对象。

DateTime

等效于的值的 value日期和时间，或者 DateTime.MinValue 的日期和时间等效项（如果 value 为 null）。

例外

FormatException

value 不是格式正确的日期和时间字符串。

示例

以下示例使用 IFormatProvider 对象通过 ToDateTime 方法转换日期值的字符串表示形式。

using System;
using System.Globalization;

public class Example
{
   public static void Main()
   {
      Console.WriteLine("{0,-18}{1,-12}{2}\n", "Date String", "Culture", "Result");

      string[] cultureNames = { "en-US", "ru-RU","ja-JP" };
      string[] dateStrings = { "01/02/09", "2009/02/03",  "01/2009/03",
                               "01/02/2009", "21/02/09", "01/22/09",
                               "01/02/23" };
      // Iterate each culture name in the array.
      foreach (string cultureName in cultureNames)
      {
         CultureInfo culture = new CultureInfo(cultureName);

         // Parse each date using the designated culture.
         foreach (string dateStr in dateStrings)
         {
            DateTime dateTimeValue;
            try {
               dateTimeValue = Convert.ToDateTime(dateStr, culture);
                // Display the date and time in a fixed format.
                Console.WriteLine("{0,-18}{1,-12}{2:yyyy-MMM-dd}",
                                  dateStr, cultureName, dateTimeValue);
            }
            catch (FormatException e) {
                Console.WriteLine("{0,-18}{1,-12}{2}",
                                  dateStr, cultureName, e.GetType().Name);
            }
         }
         Console.WriteLine();
      }
   }
}

open System
open System.Globalization

printfn $"""{"Date String",-18}{"Culture",-12}{"Result"}\n"""

let cultureNames = [ "en-US"; "ru-RU"; "ja-JP" ]
let dateStrings =
    [ "01/02/09"; "2009/02/03"; "01/2009/03"
      "01/02/2009"; "21/02/09"; "01/22/09"; "01/02/23" ]
// Iterate each culture name in the array.
for cultureName in cultureNames do
    let culture = CultureInfo cultureName

    // Parse each date using the designated culture.
    for dateStr in dateStrings do
        try
            let dateTimeValue = Convert.ToDateTime(dateStr, culture)
            // Display the date and time in a fixed format.
            printfn $"""{dateStr,-18}{cultureName,-12}{dateTimeValue.ToString "yyyy-MMM-dd"}"""
        with :? FormatException as e ->
            printfn $"{dateStr,-18}{cultureName,-12}{e.GetType().Name}"
    printfn ""

Imports System.Globalization

Module Example
   Public Sub Main( )
      Console.WriteLine("{0,-18}{1,-12}{2}", "Date String", "Culture", "Result")
      Console.WriteLine()

      Dim cultureNames() As String = { "en-US", "ru-RU","ja-JP" }
      Dim dateStrings() As String = { "01/02/09", "2009/02/03",  "01/2009/03", _
                                      "01/02/2009", "21/02/09", "01/22/09",   _
                                      "01/02/23" }
      ' Iterate each culture name in the array.
      For Each cultureName As String In cultureNames
         Dim culture As CultureInfo = New CultureInfo(cultureName)
        
         ' Parse each date using the designated culture.
         For Each dateStr As String In dateStrings
            Dim dateTimeValue As DateTime
            Try
               dateTimeValue = Convert.ToDateTime(dateStr, culture)
                ' Display the date and time in a fixed format.
                Console.WriteLine("{0,-18}{1,-12}{2:yyyy-MMM-dd}", _
                                  dateStr, cultureName, dateTimeValue)
            Catch e As FormatException 
                Console.WriteLine("{0,-18}{1,-12}{2}", _
                                  dateStr, cultureName, e.GetType().Name)
            End Try            
         Next
         Console.WriteLine()
      Next
   End Sub 
End Module 
' The example displays the following output:
'       Date String       Culture     Result
'       
'       01/02/09          en-US       2009-Jan-02
'       2009/02/03        en-US       2009-Feb-03
'       01/2009/03        en-US       2009-Jan-03
'       01/02/2009        en-US       2009-Jan-02
'       21/02/09          en-US       FormatException
'       01/22/09          en-US       2009-Jan-22
'       01/02/23          en-US       2023-Jan-02
'       
'       01/02/09          ru-RU       2009-Feb-01
'       2009/02/03        ru-RU       2009-Feb-03
'       01/2009/03        ru-RU       2009-Jan-03
'       01/02/2009        ru-RU       2009-Feb-01
'       21/02/09          ru-RU       2009-Feb-21
'       01/22/09          ru-RU       FormatException
'       01/02/23          ru-RU       2023-Feb-01
'       
'       01/02/09          ja-JP       2001-Feb-09
'       2009/02/03        ja-JP       2009-Feb-03
'       01/2009/03        ja-JP       2009-Jan-03
'       01/02/2009        ja-JP       2009-Jan-02
'       21/02/09          ja-JP       2021-Feb-09
'       01/22/09          ja-JP       FormatException
'       01/02/23          ja-JP       2001-Feb-23

注解

返回值是在上value调用 DateTime.Parse(String, IFormatProvider) 方法的结果。

provider 是获取 IFormatProvider DateTimeFormatInfo 对象的实例。对象 DateTimeFormatInfo 提供有关格式的 value区域性特定信息。如果 provider 为 null， DateTimeFormatInfo 则使用当前区域性的。

如果希望在转换失败时不处理异常，可以改为调用 DateTime.TryParse 方法。它返回一个 Boolean 值，该值指示转换是成功还是失败。

另请参阅

分析 .NET 中的日期和时间字符串

适用于

ToDateTime(UInt64)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

重要

此 API 不符合 CLS。

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(System::UInt64 value);

[System.CLSCompliant(false)]
public static DateTime ToDateTime (ulong value);

[<System.CLSCompliant(false)>]
static member ToDateTime : uint64 -> DateTime

Public Shared Function ToDateTime (value As ULong) As DateTime

参数

value: UInt64

要转换的 64 位无符号整数。

DateTime

不支持此转换。不返回任何值。

属性: CLSCompliantAttribute

例外

InvalidCastException

不支持此转换。

另请参阅

UInt64

适用于

ToDateTime(Object, IFormatProvider)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

使用指定的区域性特定格式设置信息将指定对象的值转换为 DateTime 对象。

public:
 static DateTime ToDateTime(System::Object ^ value, IFormatProvider ^ provider);

public static DateTime ToDateTime (object value, IFormatProvider provider);

public static DateTime ToDateTime (object? value, IFormatProvider? provider);

static member ToDateTime : obj * IFormatProvider -> DateTime

Public Shared Function ToDateTime (value As Object, provider As IFormatProvider) As DateTime

参数

value: Object

一个实现 IConvertible 接口的对象。

provider: IFormatProvider

一个提供区域性特定的格式设置信息的对象。

DateTime

等效于的值的 value日期和时间，或者 DateTime.MinValue 的日期和时间等效项（如果 value 为 null）。

例外

FormatException

value 是无效的日期和时间值。

InvalidCastException

value 不实现 IConvertible 接口。

或

不支持该转换。

示例

以下示例定义一个自定义格式提供程序， CustomProvider其 GetFormat 方法将消息输出到已调用它的控制台，然后返回 DateTimeFormatInfo 其名称作为参数传递给其类构造函数的区域性的对象。其中 CustomProvider 每个对象都用于将对象数组中的元素转换为日期和时间值。输出指示 CustomProvider 仅当参数的类型 value 为 String时，才会在转换中使用对象。

using System;
using System.Globalization;

public class Example
{
   public static void Main()
   {
      string[] cultureNames = { "en-US", "hu-HU", "pt-PT" };
      object[] objects = { 12, 17.2, false, new DateTime(2010, 1, 1), "today",
                           new System.Collections.ArrayList(), 'c',
                           "05/10/2009 6:13:18 PM", "September 8, 1899" };

      foreach (string cultureName in cultureNames)
      {
         Console.WriteLine("{0} culture:", cultureName);
         CustomProvider provider = new CustomProvider(cultureName);
         foreach (object obj in objects)
         {
            try {
               DateTime dateValue = Convert.ToDateTime(obj, provider);
               Console.WriteLine("{0} --> {1}", obj,
                                 dateValue.ToString(new CultureInfo(cultureName)));
            }
            catch (FormatException) {
               Console.WriteLine("{0} --> Bad Format", obj);
            }
            catch (InvalidCastException) {
               Console.WriteLine("{0} --> Conversion Not Supported", obj);
            }
         }
         Console.WriteLine();
      }
   }
}

public class CustomProvider : IFormatProvider
{
   private string cultureName;

   public CustomProvider(string cultureName)
   {
      this.cultureName = cultureName;
   }

   public object GetFormat(Type formatType)
   {
      if (formatType == typeof(DateTimeFormatInfo))
      {
         Console.Write("(CustomProvider retrieved.) ");
         return new CultureInfo(cultureName).GetFormat(formatType);
      }
      else
      {
         return null;
      }
   }
}
// The example displays the following output:
//    en-US culture:
//    12 --> Conversion Not Supported
//    17.2 --> Conversion Not Supported
//    False --> Conversion Not Supported
//    1/1/2010 12:00:00 AM --> 1/1/2010 12:00:00 AM
//    (CustomProvider retrieved.) today --> Bad Format
//    System.Collections.ArrayList --> Conversion Not Supported
//    c --> Conversion Not Supported
//    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 5/10/2009 6:13:18 PM
//    (CustomProvider retrieved.) September 8, 1899 --> 9/8/1899 12:00:00 AM
//
//    hu-HU culture:
//    12 --> Conversion Not Supported
//    17.2 --> Conversion Not Supported
//    False --> Conversion Not Supported
//    1/1/2010 12:00:00 AM --> 2010. 01. 01. 0:00:00
//    (CustomProvider retrieved.) today --> Bad Format
//    System.Collections.ArrayList --> Conversion Not Supported
//    c --> Conversion Not Supported
//    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 2009. 05. 10. 18:13:18
//    (CustomProvider retrieved.) September 8, 1899 --> 1899. 09. 08. 0:00:00
//
//    pt-PT culture:
//    12 --> Conversion Not Supported
//    17.2 --> Conversion Not Supported
//    False --> Conversion Not Supported
//    1/1/2010 12:00:00 AM --> 01-01-2010 0:00:00
//    (CustomProvider retrieved.) today --> Bad Format
//    System.Collections.ArrayList --> Conversion Not Supported
//    c --> Conversion Not Supported
//    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 05-10-2009 18:13:18
//    (CustomProvider retrieved.) September 8, 1899 --> 08-09-1899 0:00:00

open System
open System.Globalization

type CustomProvider(cultureName: string) =
    interface IFormatProvider with
        member _.GetFormat(formatType) =
            if formatType = typeof<DateTimeFormatInfo> then
                printf "(CustomProvider retrieved.) "
                CultureInfo(cultureName).GetFormat formatType
            else
                null

let cultureNames = [ "en-US"; "hu-HU"; "pt-PT" ]
let objects: obj list =
    [ 12; 17.2; false; DateTime(2010, 1, 1); "today"
      System.Collections.ArrayList(); 'c'
      "05/10/2009 6:13:18 PM"; "September 8, 1899" ]

for cultureName in cultureNames do
    printfn $"{cultureName} culture:"
    let provider = CustomProvider cultureName
    for obj in objects do
        try
            let dateValue = Convert.ToDateTime(obj, provider)
            printfn $"{obj} --> {dateValue.ToString(CultureInfo cultureName)}"
        with
        | :? FormatException ->
            printfn $"{obj} --> Bad Format"
        | :? InvalidCastException ->
            printfn $"{obj} --> Conversion Not Supported"
    printfn ""

// The example displays the following output:
//    en-US culture:
//    12 --> Conversion Not Supported
//    17.2 --> Conversion Not Supported
//    False --> Conversion Not Supported
//    1/1/2010 12:00:00 AM --> 1/1/2010 12:00:00 AM
//    (CustomProvider retrieved.) today --> Bad Format
//    System.Collections.ArrayList --> Conversion Not Supported
//    c --> Conversion Not Supported
//    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 5/10/2009 6:13:18 PM
//    (CustomProvider retrieved.) September 8, 1899 --> 9/8/1899 12:00:00 AM
//
//    hu-HU culture:
//    12 --> Conversion Not Supported
//    17.2 --> Conversion Not Supported
//    False --> Conversion Not Supported
//    1/1/2010 12:00:00 AM --> 2010. 01. 01. 0:00:00
//    (CustomProvider retrieved.) today --> Bad Format
//    System.Collections.ArrayList --> Conversion Not Supported
//    c --> Conversion Not Supported
//    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 2009. 05. 10. 18:13:18
//    (CustomProvider retrieved.) September 8, 1899 --> 1899. 09. 08. 0:00:00
//
//    pt-PT culture:
//    12 --> Conversion Not Supported
//    17.2 --> Conversion Not Supported
//    False --> Conversion Not Supported
//    1/1/2010 12:00:00 AM --> 01-01-2010 0:00:00
//    (CustomProvider retrieved.) today --> Bad Format
//    System.Collections.ArrayList --> Conversion Not Supported
//    c --> Conversion Not Supported
//    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 05-10-2009 18:13:18
//    (CustomProvider retrieved.) September 8, 1899 --> 08-09-1899 0:00:00

Imports System.Globalization

Module Example
   Public Sub Main()
      Dim cultureNames() As String = { "en-US", "hu-HU", "pt-PT" }
      Dim objects() As Object = { 12, 17.2, False, #1/1/2010#, "today", _
                                  New System.Collections.ArrayList(), "c"c, _
                                  "05/10/2009 6:13:18 PM", "September 8, 1899" }
      
      For Each cultureName As String In cultureNames
         Console.WriteLine("{0} culture:", cultureName)
         Dim provider As New CustomProvider(cultureName)
         For Each obj As Object In objects
            Try
               Dim dateValue As Date = Convert.ToDateTime(obj, provider)      
               Console.WriteLine("{0} --> {1}", obj, _
                                 dateValue.ToString(New CultureInfo(cultureName)))
            Catch e As FormatException
               Console.WriteLine("{0} --> Bad Format", obj)
            Catch e As InvalidCastException
               Console.WriteLine("{0} --> Conversion Not Supported", obj)
            End Try
         Next
         Console.WriteLine()
      Next
   End Sub
End Module

Public Class CustomProvider : Implements IFormatProvider
   Private cultureName As String
   
   Public Sub New(cultureName As String)
      Me.cultureName = cultureName
   End Sub
   
   Public Function GetFormat(formatType As Type) As Object _
          Implements IFormatProvider.GetFormat
      If formatType Is GetType(DateTimeFormatInfo) Then
         Console.Write("(CustomProvider retrieved.) ")
         Return New CultureInfo(cultureName).GetFormat(formatType)
      Else
         Return Nothing
      End If   
   End Function
End Class
' The example displays the following output:
'    en-US culture:
'    12 --> Conversion Not Supported
'    17.2 --> Conversion Not Supported
'    False --> Conversion Not Supported
'    1/1/2010 12:00:00 AM --> 1/1/2010 12:00:00 AM
'    (CustomProvider retrieved.) today --> Bad Format
'    System.Collections.ArrayList --> Conversion Not Supported
'    c --> Conversion Not Supported
'    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 5/10/2009 6:13:18 PM
'    (CustomProvider retrieved.) September 8, 1899 --> 9/8/1899 12:00:00 AM
'    
'    hu-HU culture:
'    12 --> Conversion Not Supported
'    17.2 --> Conversion Not Supported
'    False --> Conversion Not Supported
'    1/1/2010 12:00:00 AM --> 2010. 01. 01. 0:00:00
'    (CustomProvider retrieved.) today --> Bad Format
'    System.Collections.ArrayList --> Conversion Not Supported
'    c --> Conversion Not Supported
'    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 2009. 05. 10. 18:13:18
'    (CustomProvider retrieved.) September 8, 1899 --> 1899. 09. 08. 0:00:00
'    
'    pt-PT culture:
'    12 --> Conversion Not Supported
'    17.2 --> Conversion Not Supported
'    False --> Conversion Not Supported
'    1/1/2010 12:00:00 AM --> 01-01-2010 0:00:00
'    (CustomProvider retrieved.) today --> Bad Format
'    System.Collections.ArrayList --> Conversion Not Supported
'    c --> Conversion Not Supported
'    (CustomProvider retrieved.) 05/10/2009 6:13:18 PM --> 05-10-2009 18:13:18
'    (CustomProvider retrieved.) September 8, 1899 --> 08-09-1899 0:00:00

注解

返回值是调用 IConvertible.ToDateTime 的基础类型的 value方法的结果。

provider 使用户能够指定有关的内容 value的区域性特定转换信息。例如，如果 value 是 String 表示日期的， provider 则可提供有关用于表示该日期的表示法的区域性特定信息。 provider如果的value运行时类型是，String或者如果 value 是其实现使用的用户provider定义类型IConvertible.ToDateTime，则涉及的转换value。如果的 value 运行时类型为 String 且 provider 为 null，则 CultureInfo 使用表示当前区域性的对象。

另请参阅

分析 .NET 中的日期和时间字符串

适用于

ToDateTime(SByte)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

重要

此 API 不符合 CLS。

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(System::SByte value);

[System.CLSCompliant(false)]
public static DateTime ToDateTime (sbyte value);

[<System.CLSCompliant(false)>]
static member ToDateTime : sbyte -> DateTime

Public Shared Function ToDateTime (value As SByte) As DateTime

参数

value: SByte

要转换的 8 位带符号整数。

DateTime

不支持此转换。不返回任何值。

属性: CLSCompliantAttribute

例外

InvalidCastException

不支持此转换。

另请参阅

Byte

适用于

ToDateTime(UInt32)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

重要

此 API 不符合 CLS。

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(System::UInt32 value);

[System.CLSCompliant(false)]
public static DateTime ToDateTime (uint value);

[<System.CLSCompliant(false)>]
static member ToDateTime : uint32 -> DateTime

Public Shared Function ToDateTime (value As UInteger) As DateTime

参数

value: UInt32

要转换的 32 位无符号整数。

DateTime

不支持此转换。不返回任何值。

属性: CLSCompliantAttribute

例外

InvalidCastException

不支持此转换。

另请参阅

UInt32

适用于

ToDateTime(Object)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

将指定对象的值转换为 DateTime 对象。

public:
 static DateTime ToDateTime(System::Object ^ value);

public static DateTime ToDateTime (object value);

public static DateTime ToDateTime (object? value);

static member ToDateTime : obj -> DateTime

Public Shared Function ToDateTime (value As Object) As DateTime

参数

value: Object

用于实现 IConvertible 接口的对象，或为 null。

DateTime

等效于的值的value日期和时间，如果 value 为 null，则为 DateTime.MinValue 的日期和时间等效项。

例外

FormatException

value 是无效的日期和时间值。

InvalidCastException

value 不实现 IConvertible 接口。

或

不支持该转换。

示例

以下示例使用各种Object变量调用 ToDateTime(Object) 方法。

using System;

public class ConversionToDateTime
{
   public static void Main()
   {
      // Try converting an integer.
      int number = 16352;
      ConvertToDateTime(number);

      // Convert a null.
      object obj = null;
      ConvertToDateTime(obj);

      // Convert a non-date string.
      string nonDateString = "monthly";
      ConvertToDateTime(nonDateString);

      // Try to convert various date strings.
      string dateString;
      dateString = "05/01/1996";
      ConvertToDateTime(dateString);
      dateString = "Tue Apr 28, 2009";
      ConvertToDateTime(dateString);
      dateString = "06 July 2008 7:32:47 AM";
      ConvertToDateTime(dateString);
      dateString = "17:32:47.003";
      ConvertToDateTime(dateString);
   }

   private static void ConvertToDateTime(object value)
   {
      DateTime convertedDate;
      try {
         convertedDate = Convert.ToDateTime(value);
         Console.WriteLine("'{0}' converts to {1}.", value, convertedDate);
      }
      catch (FormatException) {
         Console.WriteLine("'{0}' is not in the proper format.", value);
      }
      catch (InvalidCastException) {
         Console.WriteLine("Conversion of the {0} '{1}' is not supported",
                           value.GetType().Name, value);
      }
   }
}
// The example displays the following output:
//       Conversion of the Int32 '16352' is not supported
//       '' converts to 1/1/0001 12:00:00 AM.
//       'monthly' is not in the proper format.
//       '05/01/1996' converts to 5/1/1996 12:00:00 AM.
//       'Tue Apr 28, 2009' converts to 4/28/2009 12:00:00 AM.
//       '06 July 2008 7:32:47 AM' converts to 7/6/2008 7:32:47 AM.
//       '17:32:47.003' converts to 5/28/2008 5:32:47 PM.

open System

let convertToDateTime (value: obj) =
    try
        let convertedDate = Convert.ToDateTime value
        printfn $"'{value}' converts to {convertedDate}."
    with
    | :? FormatException ->
        printfn $"'{value}' is not in the proper format."
    | :? InvalidCastException ->
        printfn $"Conversion of the {value.GetType().Name} '{value}' is not supported"

[<EntryPoint>]
let main _ =
    // Try converting an integer.
    let number = 16352
    convertToDateTime number

    // Convert a null.
    let obj = box null
    convertToDateTime obj

    // Convert a non-date string.
    let nonDateString = "monthly"
    convertToDateTime nonDateString

    // Try to convert various date strings.
    let dateString = "05/01/1996"
    convertToDateTime dateString
    let dateString = "Tue Apr 28, 2009"
    convertToDateTime dateString
    let dateString = "06 July 2008 7:32:47 AM"
    convertToDateTime dateString
    let dateString = "17:32:47.003"
    convertToDateTime dateString

    0

// The example displays the following output:
//       Conversion of the Int32 '16352' is not supported
//       '' converts to 1/1/0001 12:00:00 AM.
//       'monthly' is not in the proper format.
//       '05/01/1996' converts to 5/1/1996 12:00:00 AM.
//       'Tue Apr 28, 2009' converts to 4/28/2009 12:00:00 AM.
//       '06 July 2008 7:32:47 AM' converts to 7/6/2008 7:32:47 AM.
//       '17:32:47.003' converts to 5/28/2008 5:32:47 PM.

Module ConversionToDateTime
   Public Sub Main()
      ' Try converting an integer.
      Dim number As Integer = 16352
      ConvertToDateTime(number)
      
      ' Convert a null.
      Dim obj As Object = Nothing
      ConvertToDateTime(obj)
      
      ' Convert a non-date string.
      Dim nonDateString As String = "monthly"
      ConvertToDateTime(nonDateString)
      
      ' Try to convert various dates.
      Dim dateString As String 
      dateString = "05/01/1996"
      ConvertToDateTime(dateString)
      dateString = "Tue Apr 28, 2009"
      ConvertToDateTime(dateString)
      dateString = "06 July 2008 7:32:47 AM"
      ConvertToDateTime(dateString)
      dateString = "17:32:47.003"
      ConvertToDateTime(dateString)
   End Sub
   
   Private Sub ConvertToDateTime(value As Object)
      Dim convertedDate As Date
      Try
         convertedDate = Convert.ToDateTime(value)
         Console.WriteLine("'{0}' converts to {1}.", value, convertedDate)
      Catch e As FormatException
         Console.WriteLine("'{0}' is not in the proper format.", value)
      Catch e As InvalidCastException
         Console.WriteLine("Conversion of the {0} '{1}' is not supported", _
                           value.GetType().Name, value)
      End Try
   End Sub
End Module
' The example displays the following output:
'       Conversion of the Int32 '16352' is not supported
'       '' converts to 1/1/0001 12:00:00 AM.
'       'monthly' is not in the proper format.
'       '05/01/1996' converts to 5/1/1996 12:00:00 AM.
'       'Tue Apr 28, 2009' converts to 4/28/2009 12:00:00 AM.
'       '06 July 2008 7:32:47 AM' converts to 7/6/2008 7:32:47 AM.
'       '17:32:47.003' converts to 5/28/2008 5:32:47 PM.

注解

要使转换成功，参数的 value 运行时类型必须是 DateTime 或 String，或者 value 必须是 null。否则，方法将 InvalidCastException引发。此外，如果 value 是字符串，则它必须包含当前区域性中的日期和时间值的有效表示形式，否则 FormatException 会引发。

返回值是调用 IConvertible.ToDateTime 的基础类型的 value方法的结果。

适用于

ToDateTime(Int16)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(short value);

public static DateTime ToDateTime (short value);

static member ToDateTime : int16 -> DateTime

Public Shared Function ToDateTime (value As Short) As DateTime

参数

value: Int16

要转换的 16 位带符号整数。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

另请参阅

Int16

适用于

ToDateTime(Int32)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(int value);

public static DateTime ToDateTime (int value);

static member ToDateTime : int -> DateTime

Public Shared Function ToDateTime (value As Integer) As DateTime

参数

value: Int32

要转换的 32 位带符号整数。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

另请参阅

Int32

适用于

ToDateTime(Int64)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(long value);

public static DateTime ToDateTime (long value);

static member ToDateTime : int64 -> DateTime

Public Shared Function ToDateTime (value As Long) As DateTime

参数

value: Int64

要转换的 64 位带符号整数。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

另请参阅

Int64

适用于

ToDateTime(Double)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(double value);

public static DateTime ToDateTime (double value);

static member ToDateTime : double -> DateTime

Public Shared Function ToDateTime (value As Double) As DateTime

参数

value: Double

要转换的双精度浮点值。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

另请参阅

Double

适用于

ToDateTime(Decimal)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(System::Decimal value);

public static DateTime ToDateTime (decimal value);

static member ToDateTime : decimal -> DateTime

Public Shared Function ToDateTime (value As Decimal) As DateTime

参数

value: Decimal

要转换的数字。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

适用于

ToDateTime(DateTime)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

返回指定的 DateTime 对象；不执行任何实际的转换。

public:
 static DateTime ToDateTime(DateTime value);

public static DateTime ToDateTime (DateTime value);

static member ToDateTime : DateTime -> DateTime

Public Shared Function ToDateTime (value As DateTime) As DateTime

参数

value: DateTime

日期和时间值。

DateTime

不经更改即返回 value。

适用于

ToDateTime(Char)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(char value);

public static DateTime ToDateTime (char value);

static member ToDateTime : char -> DateTime

Public Shared Function ToDateTime (value As Char) As DateTime

参数

value: Char

要转换的 Unicode 字符。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

另请参阅

Char

适用于

ToDateTime(Byte)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(System::Byte value);

public static DateTime ToDateTime (byte value);

static member ToDateTime : byte -> DateTime

Public Shared Function ToDateTime (value As Byte) As DateTime

参数

value: Byte

要转换的 8 位无符号整数。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

另请参阅

Byte

适用于

ToDateTime(Boolean)

Source:: Convert.cs

Source:: Convert.cs

Source:: Convert.cs

调用此方法始终引发 InvalidCastException。

public:
 static DateTime ToDateTime(bool value);

public static DateTime ToDateTime (bool value);

static member ToDateTime : bool -> DateTime

Public Shared Function ToDateTime (value As Boolean) As DateTime

参数

value: Boolean

要转换的布尔值。

DateTime

不支持此转换。不返回任何值。

例外

InvalidCastException

不支持此转换。

另请参阅

Boolean

适用于

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