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C# 中的日期時間對象（開發人員如何使用）

發佈 2024年4月3日
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介紹

DateTime 物件在 C# 中是用於 .NET Framework 應用程式中處理日期和時間的基本單位。它們提供了一組強大的功能，用於操作、格式化和比較日期和時間。

本文旨在全面概述 C# 中的 DateTime 物件，涵蓋它們的創建、操作、格式化及常見用例。在本文的最後，我們還將探討如何 IronPDF 從 Iron Software 可以在 C# 應用程式中即時生成 PDF 文件。

建立 DateTime 物件

在 C# 中建立一個 DateTime 物件是很簡單的。有多種建構函式可用來用不同的參數初始化 DateTime 物件：

// Current date and time
DateTime currentDateTime = DateTime.Now;
// Specific date and time
DateTime specificDateTime = new DateTime(2024, 3, 16, 10, 30, 0);
// Date only
DateTime dateOnly = DateTime.Today;
// Date and time in UTC
DateTime utcDateTime = DateTime.UtcNow;
// Current date and time
DateTime currentDateTime = DateTime.Now;
// Specific date and time
DateTime specificDateTime = new DateTime(2024, 3, 16, 10, 30, 0);
// Date only
DateTime dateOnly = DateTime.Today;
// Date and time in UTC
DateTime utcDateTime = DateTime.UtcNow;
' Current date and time
Dim currentDateTime As DateTime = DateTime.Now
' Specific date and time
Dim specificDateTime As New DateTime(2024, 3, 16, 10, 30, 0)
' Date only
Dim dateOnly As DateTime = DateTime.Today
' Date and time in UTC
Dim utcDateTime As DateTime = DateTime.UtcNow
VB   C#

操作 DateTime 物件

DateTime 物件提供多種方法來操作日期和時間，例如增加或減少時間間隔、擷取組件和在時區之間轉換。

DateTime now = DateTime.Now;
// Adding days
DateTime futureDate = now.AddDays(7);
// Subtracting hours
DateTime pastTime = now.AddHours(-3);
// Getting components
int year = now.Year;
int month = now.Month;
int day = now.Day;
int hour = now.Hour;
int minute = now.Minute;
int second = now.Second;
// Converting between time zones
DateTime utcTime = DateTime.UtcNow;
DateTime localTime = utcTime.ToLocalTime();
DateTime now = DateTime.Now;
// Adding days
DateTime futureDate = now.AddDays(7);
// Subtracting hours
DateTime pastTime = now.AddHours(-3);
// Getting components
int year = now.Year;
int month = now.Month;
int day = now.Day;
int hour = now.Hour;
int minute = now.Minute;
int second = now.Second;
// Converting between time zones
DateTime utcTime = DateTime.UtcNow;
DateTime localTime = utcTime.ToLocalTime();
Dim now As DateTime = DateTime.Now
' Adding days
Dim futureDate As DateTime = now.AddDays(7)
' Subtracting hours
Dim pastTime As DateTime = now.AddHours(-3)
' Getting components
Dim year As Integer = now.Year
Dim month As Integer = now.Month
Dim day As Integer = now.Day
Dim hour As Integer = now.Hour
Dim minute As Integer = now.Minute
Dim second As Integer = now.Second
' Converting between time zones
Dim utcTime As DateTime = DateTime.UtcNow
Dim localTime As DateTime = utcTime.ToLocalTime()
VB   C#

格式化 DateTime 物件

DateTime 物件表示可以使用各種格式指定符來格式化成字串的時間或日期，以符合所需格式。

DateTime dateTime = DateTime.Now;
// Standard date and time format
string standardFormat = dateTime.ToString("G");
// Custom format
string customFormat = dateTime.ToString("dd/MM/yyyy HH:mm:ss");
// Format for sorting
string sortableFormat = dateTime.ToString("yyyy-MM-ddTHH:mm:ss");
DateTime dateTime = DateTime.Now;
// Standard date and time format
string standardFormat = dateTime.ToString("G");
// Custom format
string customFormat = dateTime.ToString("dd/MM/yyyy HH:mm:ss");
// Format for sorting
string sortableFormat = dateTime.ToString("yyyy-MM-ddTHH:mm:ss");
Imports System

Dim dateTime As DateTime = DateTime.Now
' Standard date and time format
Dim standardFormat As String = dateTime.ToString("G")
' Custom format
Dim customFormat As String = dateTime.ToString("dd/MM/yyyy HH:mm:ss")
' Format for sorting
Dim sortableFormat As String = dateTime.ToString("yyyy-MM-ddTHH:mm:ss")
VB   C#

比較 DateTime 物件

C# 提供了標準的比較運算子 (<, >, <=, >=, ==!=) 可以直接比較兩個DateTime物件。這些運算符比較DateTime`物件底層的 ticks，這些 ticks 表示自公曆 0001 年 1 月 1 日 00:00:00.000 起經過的 100 奈秒間隔的數量。

以下是一個示例，展示了比較運算符的使用：

DateTime date1 = DateTime.Now;
DateTime date2 = DateTime.Now.AddDays(1);
if (date1 < date2)
{
    Console.WriteLine("date1 is earlier than date2.");
}
else if (date1 > date2)
{
    Console.WriteLine("date1 is later than date2.");
}
else
{
    Console.WriteLine("date1 is equal to date2.");
}
DateTime date1 = DateTime.Now;
DateTime date2 = DateTime.Now.AddDays(1);
if (date1 < date2)
{
    Console.WriteLine("date1 is earlier than date2.");
}
else if (date1 > date2)
{
    Console.WriteLine("date1 is later than date2.");
}
else
{
    Console.WriteLine("date1 is equal to date2.");
}
Dim date1 As DateTime = DateTime.Now
Dim date2 As DateTime = DateTime.Now.AddDays(1)
If date1 < date2 Then
	Console.WriteLine("date1 is earlier than date2.")
ElseIf date1 > date2 Then
	Console.WriteLine("date1 is later than date2.")
Else
	Console.WriteLine("date1 is equal to date2.")
End If
VB   C#

使用 DateTime.Compare C# 方法

除了比較運算子，DateTime 物件還提供方法來比較這些物件之間的相對值。在某些情況下，這些方法提供了更多的靈活性和可讀性。CompareTo()該方法比較底層的 DateTime 對象來確定結果。

它假設兩個日期在相同的時區值中。在比較對象後，它返回一個整數值，指示大於、小於或等於。相同日期值返回整數值零。

DateTime date1 = DateTime.Now;
DateTime date2 = DateTime.Now.AddDays(1);
int result = date1.CompareTo(date2);
if (result < 0)
{
    Console.WriteLine("date1 is earlier than date2.");
}
else if (result > 0)
{
    Console.WriteLine("date1 is later than date2.");
}
else
{
    Console.WriteLine("date1 is equal to date2.");
}
DateTime date1 = DateTime.Now;
DateTime date2 = DateTime.Now.AddDays(1);
int result = date1.CompareTo(date2);
if (result < 0)
{
    Console.WriteLine("date1 is earlier than date2.");
}
else if (result > 0)
{
    Console.WriteLine("date1 is later than date2.");
}
else
{
    Console.WriteLine("date1 is equal to date2.");
}
Dim date1 As DateTime = DateTime.Now
Dim date2 As DateTime = DateTime.Now.AddDays(1)
Dim result As Integer = date1.CompareTo(date2)
If result < 0 Then
	Console.WriteLine("date1 is earlier than date2.")
ElseIf result > 0 Then
	Console.WriteLine("date1 is later than date2.")
Else
	Console.WriteLine("date1 is equal to date2.")
End If
VB   C#

比較 DateTime 物件的容忍度

在比較 DateTime 物件時，尤其是在處理涉及時間間隔的計算時，考慮到精確度可能有所差異，因此設置容忍度是很重要的。

這可以通過比較兩個 DateTime 值之間的絕對差與預定的容忍閾值來實現。

class Program
{
    public static void Main()
    {
DateTime date1 = DateTime.Now;
DateTime date2 = DateTime.Now.AddMilliseconds(10);
TimeSpan tolerance = TimeSpan.FromMilliseconds(5);
bool isEqual = Math.Abs((date1 - date2).TotalMilliseconds) <= tolerance.TotalMilliseconds;
if (isEqual)
{
    Console.WriteLine("date1 is considered equal to date2 within the tolerance.");
}
else
{
    Console.WriteLine("date1 is not equal to date2 within the tolerance.");
}
}
}
class Program
{
    public static void Main()
    {
DateTime date1 = DateTime.Now;
DateTime date2 = DateTime.Now.AddMilliseconds(10);
TimeSpan tolerance = TimeSpan.FromMilliseconds(5);
bool isEqual = Math.Abs((date1 - date2).TotalMilliseconds) <= tolerance.TotalMilliseconds;
if (isEqual)
{
    Console.WriteLine("date1 is considered equal to date2 within the tolerance.");
}
else
{
    Console.WriteLine("date1 is not equal to date2 within the tolerance.");
}
}
}
Friend Class Program
	Public Shared Sub Main()
Dim date1 As DateTime = DateTime.Now
Dim date2 As DateTime = DateTime.Now.AddMilliseconds(10)
Dim tolerance As TimeSpan = TimeSpan.FromMilliseconds(5)
Dim isEqual As Boolean = Math.Abs((date1.Subtract(date2)).TotalMilliseconds) <= tolerance.TotalMilliseconds
If isEqual Then
	Console.WriteLine("date1 is considered equal to date2 within the tolerance.")
Else
	Console.WriteLine("date1 is not equal to date2 within the tolerance.")
End If
	End Sub
End Class
VB   C#

處理時區和日光節約時間

DateTime 對象在 C# 中可以表示當地時間和協調世界時間 (協調世界時). 尤其是在處理全球應用程序時，瞭解時區轉換非常重要。

DateTime localTime = DateTime.Now;
DateTime utcTime = DateTime.UtcNow;
Console.WriteLine("Local Time: " + localTime);
Console.WriteLine("UTC Time: " + utcTime);
DateTime localTime = DateTime.Now;
DateTime utcTime = DateTime.UtcNow;
Console.WriteLine("Local Time: " + localTime);
Console.WriteLine("UTC Time: " + utcTime);
Dim localTime As DateTime = DateTime.Now
Dim utcTime As DateTime = DateTime.UtcNow
Console.WriteLine("Local Time: " & localTime)
Console.WriteLine("UTC Time: " & utcTime)
VB   C#

使用 IronPDF 在 C# 中生成 PDF 文件

Iron Software 的 IronPDF 是一個高效且易於使用的 PDF 生成庫。我們可以使用 NuGet 套件管理工具來安裝它。

C# 中的日期時間物件（開發人員如何使用）：圖1

NuGet\Install-Package IronPdf -Version 2024.3.4

或從 Visual Studio 如下所示

C# 中的日期時間物件（開發者指導）：圖2 - 使用NuGet套件管理器安裝IronPDF

現在讓我們深入 PDF 生成，來演示一個 DateTime 物件。

class Program
{
    static void Main()
    {
        Console.WriteLine("-----------Iron Software-------------");
        var renderer = new ChromePdfRenderer(); // var pattern
        var content = " <h1> Iron Software is Awesome </h1> Made with IronPDF!";
        content += "<h2>Demo Datetime Objects in C#</h2>";
        // Current date and time
        content += "<h3>Current date and time</h3>";
        DateTime currentDateTime = DateTime.Now;
        content += $"<p>Current date and time: {currentDateTime:U}</p>";
        Console.WriteLine($"Current date and time: {currentDateTime:U}");
        // Specific date and time
        content += "<h3>Specific date and time</h3>";
        DateTime specificDateTime = new DateTime(2024, 3, 16, 10, 30, 0);
        content += $"<p>Specific date and time: {specificDateTime:U}</p>";
        Console.WriteLine($"Specific date and time: {specificDateTime:U}");
        // Date only
        content += "<h3>Date Only</h3>";
        DateTime dateOnly = DateTime.Today;
        content += $"<p>Date only: {dateOnly:U}</p>";
        Console.WriteLine($"Date only: {dateOnly:U}");
        // Date and time in UTC
        content += "<h3>Date and time in UTC</h3>";
        DateTime utcDateTime = DateTime.UtcNow;
        content += $"<p>Date only: {dateOnly:U}</p>";
        Console.WriteLine($"Date only: {dateOnly:U}");
        //Compare dates with Operators
        content += "<h3>Compare dates with Operators</h3>";
        DateTime date1 = DateTime.Now;
        DateTime date2 = DateTime.Now.AddDays(1);
        content += $"<p>Compare date1 {date1:d}, date2 {date2:d}: {CompareDates(date1, date2)}</p>";
        Console.WriteLine($"Compare date1 {date1:U}, date2 {date2:U}: {dateOnly:U}");
        //Compare dates with Compare Method
        content += "<h3>Compare dates with Compare Method</h3>";
        content += $"<p>Compare date1 {date1:d}, date2 {date2:d}: {CompareDatesWithCompare(date1, date2)}</p>";
        Console.WriteLine($"Compare date1 {date1:U}, date2 {date2:U}: {dateOnly:U}");
        var pdf = renderer.RenderHtmlAsPdf(content);
        pdf.SaveAs("outputDate.pdf"); // Saves PDF
    }
    public static string CompareDatesWithCompare(DateTime date1, DateTime date2)
    {
        int result = date1.CompareTo(date2);
        string resultString;
        if (result < 0)
        {
            resultString = "date1 is earlier than date2.";
            Console.WriteLine(resultString);
        }
        else if (result > 0)
        {
            resultString = "date1 is later than date2.";
            Console.WriteLine(resultString);
        }
        else
        {
            resultString = "date1 is equal to date2.";
            Console.WriteLine(resultString);
        }
        return resultString;
    }
    public static string CompareDates(DateTime date1, DateTime date2)
    {
        string result;
        if (CheckLessor(date1, date2))
        {
            result = "date1 is earlier than date2.";
            Console.WriteLine(result);
        }
        else if (CheckGreater(date1, date2))
        {
            result = "date1 is later than date2.";
            Console.WriteLine(result);
        }
        else
        {
            result = "date1 is equal to date2.";
            Console.WriteLine(result);
        }
        return result;
    }
    public static bool CheckGreater(DateTime date1, DateTime date2)
    {
        return date1 > date2;
    }
    public static bool CheckLessor(DateTime date1, DateTime date2)
    {
        return date1 < date2;
    }
}
class Program
{
    static void Main()
    {
        Console.WriteLine("-----------Iron Software-------------");
        var renderer = new ChromePdfRenderer(); // var pattern
        var content = " <h1> Iron Software is Awesome </h1> Made with IronPDF!";
        content += "<h2>Demo Datetime Objects in C#</h2>";
        // Current date and time
        content += "<h3>Current date and time</h3>";
        DateTime currentDateTime = DateTime.Now;
        content += $"<p>Current date and time: {currentDateTime:U}</p>";
        Console.WriteLine($"Current date and time: {currentDateTime:U}");
        // Specific date and time
        content += "<h3>Specific date and time</h3>";
        DateTime specificDateTime = new DateTime(2024, 3, 16, 10, 30, 0);
        content += $"<p>Specific date and time: {specificDateTime:U}</p>";
        Console.WriteLine($"Specific date and time: {specificDateTime:U}");
        // Date only
        content += "<h3>Date Only</h3>";
        DateTime dateOnly = DateTime.Today;
        content += $"<p>Date only: {dateOnly:U}</p>";
        Console.WriteLine($"Date only: {dateOnly:U}");
        // Date and time in UTC
        content += "<h3>Date and time in UTC</h3>";
        DateTime utcDateTime = DateTime.UtcNow;
        content += $"<p>Date only: {dateOnly:U}</p>";
        Console.WriteLine($"Date only: {dateOnly:U}");
        //Compare dates with Operators
        content += "<h3>Compare dates with Operators</h3>";
        DateTime date1 = DateTime.Now;
        DateTime date2 = DateTime.Now.AddDays(1);
        content += $"<p>Compare date1 {date1:d}, date2 {date2:d}: {CompareDates(date1, date2)}</p>";
        Console.WriteLine($"Compare date1 {date1:U}, date2 {date2:U}: {dateOnly:U}");
        //Compare dates with Compare Method
        content += "<h3>Compare dates with Compare Method</h3>";
        content += $"<p>Compare date1 {date1:d}, date2 {date2:d}: {CompareDatesWithCompare(date1, date2)}</p>";
        Console.WriteLine($"Compare date1 {date1:U}, date2 {date2:U}: {dateOnly:U}");
        var pdf = renderer.RenderHtmlAsPdf(content);
        pdf.SaveAs("outputDate.pdf"); // Saves PDF
    }
    public static string CompareDatesWithCompare(DateTime date1, DateTime date2)
    {
        int result = date1.CompareTo(date2);
        string resultString;
        if (result < 0)
        {
            resultString = "date1 is earlier than date2.";
            Console.WriteLine(resultString);
        }
        else if (result > 0)
        {
            resultString = "date1 is later than date2.";
            Console.WriteLine(resultString);
        }
        else
        {
            resultString = "date1 is equal to date2.";
            Console.WriteLine(resultString);
        }
        return resultString;
    }
    public static string CompareDates(DateTime date1, DateTime date2)
    {
        string result;
        if (CheckLessor(date1, date2))
        {
            result = "date1 is earlier than date2.";
            Console.WriteLine(result);
        }
        else if (CheckGreater(date1, date2))
        {
            result = "date1 is later than date2.";
            Console.WriteLine(result);
        }
        else
        {
            result = "date1 is equal to date2.";
            Console.WriteLine(result);
        }
        return result;
    }
    public static bool CheckGreater(DateTime date1, DateTime date2)
    {
        return date1 > date2;
    }
    public static bool CheckLessor(DateTime date1, DateTime date2)
    {
        return date1 < date2;
    }
}
Friend Class Program
	Shared Sub Main()
		Console.WriteLine("-----------Iron Software-------------")
		Dim renderer = New ChromePdfRenderer() ' var pattern
		Dim content = " <h1> Iron Software is Awesome </h1> Made with IronPDF!"
		content &= "<h2>Demo Datetime Objects in C#</h2>"
		' Current date and time
		content &= "<h3>Current date and time</h3>"
		Dim currentDateTime As DateTime = DateTime.Now
		content &= $"<p>Current date and time: {currentDateTime:U}</p>"
		Console.WriteLine($"Current date and time: {currentDateTime:U}")
		' Specific date and time
		content &= "<h3>Specific date and time</h3>"
		Dim specificDateTime As New DateTime(2024, 3, 16, 10, 30, 0)
		content &= $"<p>Specific date and time: {specificDateTime:U}</p>"
		Console.WriteLine($"Specific date and time: {specificDateTime:U}")
		' Date only
		content &= "<h3>Date Only</h3>"
		Dim dateOnly As DateTime = DateTime.Today
		content &= $"<p>Date only: {dateOnly:U}</p>"
		Console.WriteLine($"Date only: {dateOnly:U}")
		' Date and time in UTC
		content &= "<h3>Date and time in UTC</h3>"
		Dim utcDateTime As DateTime = DateTime.UtcNow
		content &= $"<p>Date only: {dateOnly:U}</p>"
		Console.WriteLine($"Date only: {dateOnly:U}")
		'Compare dates with Operators
		content &= "<h3>Compare dates with Operators</h3>"
		Dim date1 As DateTime = DateTime.Now
		Dim date2 As DateTime = DateTime.Now.AddDays(1)
		content &= $"<p>Compare date1 {date1:d}, date2 {date2:d}: {CompareDates(date1, date2)}</p>"
		Console.WriteLine($"Compare date1 {date1:U}, date2 {date2:U}: {dateOnly:U}")
		'Compare dates with Compare Method
		content &= "<h3>Compare dates with Compare Method</h3>"
		content &= $"<p>Compare date1 {date1:d}, date2 {date2:d}: {CompareDatesWithCompare(date1, date2)}</p>"
		Console.WriteLine($"Compare date1 {date1:U}, date2 {date2:U}: {dateOnly:U}")
		Dim pdf = renderer.RenderHtmlAsPdf(content)
		pdf.SaveAs("outputDate.pdf") ' Saves PDF
	End Sub
	Public Shared Function CompareDatesWithCompare(ByVal date1 As DateTime, ByVal date2 As DateTime) As String
		Dim result As Integer = date1.CompareTo(date2)
		Dim resultString As String
		If result < 0 Then
			resultString = "date1 is earlier than date2."
			Console.WriteLine(resultString)
		ElseIf result > 0 Then
			resultString = "date1 is later than date2."
			Console.WriteLine(resultString)
		Else
			resultString = "date1 is equal to date2."
			Console.WriteLine(resultString)
		End If
		Return resultString
	End Function
	Public Shared Function CompareDates(ByVal date1 As DateTime, ByVal date2 As DateTime) As String
		Dim result As String
		If CheckLessor(date1, date2) Then
			result = "date1 is earlier than date2."
			Console.WriteLine(result)
		ElseIf CheckGreater(date1, date2) Then
			result = "date1 is later than date2."
			Console.WriteLine(result)
		Else
			result = "date1 is equal to date2."
			Console.WriteLine(result)
		End If
		Return result
	End Function
	Public Shared Function CheckGreater(ByVal date1 As DateTime, ByVal date2 As DateTime) As Boolean
		Return date1 > date2
	End Function
	Public Shared Function CheckLessor(ByVal date1 As DateTime, ByVal date2 As DateTime) As Boolean
		Return date1 < date2
	End Function
End Class
VB   C#

以下輸出顯示了使用 DateTime 物件生成的 PDF：

C# 中的 `DateTime` 物件（開發人員如何使用）：圖 3

IronPDF 試用許可證

IronPDF請提供電子郵件地址以生成授權碼，授權碼將被發送到您提供的電子郵件。

"IronPDF.LicenseKey": "<Your Key>"
"IronPDF.LicenseKey": "<Your Key>"
'INSTANT VB TODO TASK: The following line uses invalid syntax:
'"IronPDF.LicenseKey": "<Your Key>"
VB   C#

將許可證金鑰放置在 AppSettings.Json 檔案中。

結論

DateTime 物件在 C# 中提供了一種強大方式，用於在 .NET 應用程式中處理日期和時間。它們提供了廣泛的功能，用於創建、操作、格式化和比較日期和時間值。有效地使用 DateTime 物件對於在 C# 應用程式中構建可靠且準確的日期和時間功能至關重要。

通過利用 DateTime 物件的功能，開發人員可以確保其應用程式正確處理日期和時間，無論他們遇到的具體需求或場景如何。

無論是計算持續時間、調度任務，還是向用戶顯示日期和時間，DateTime 物件在許多 C# 程式設計中與日期和時間管理相關的方面都起著至關重要的作用。

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