C# LINQ Distinct（對於開發者的運行原理）

using System.Linq;
using System.Collections.Generic;

public class DistinctExample
{
    public static void Example()
    {
        // Example list with duplicate integers
        List<int> numbers = new List<int> { 1, 2, 2, 3, 4, 4, 5 };

        // Using Distinct to remove duplicates
        var distinctNumbers = numbers.Distinct();

        // Display the distinct numbers
        foreach (var number in distinctNumbers)
        {
            Console.WriteLine(number);
        }
    }
}

Imports System.Linq
Imports System.Collections.Generic

Public Class DistinctExample
	Public Shared Sub Example()
		' Example list with duplicate integers
		Dim numbers As New List(Of Integer) From {1, 2, 2, 3, 4, 4, 5}

		' Using Distinct to remove duplicates
		Dim distinctNumbers = numbers.Distinct()

		' Display the distinct numbers
		For Each number In distinctNumbers
			Console.WriteLine(number)
		Next number
	End Sub
End Class

using System;
using System.Collections.Generic;
using System.Linq;

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class PersonEqualityComparer : IEqualityComparer<Person>
{
    public bool Equals(Person x, Person y)
    {
        return x.FirstName == y.FirstName && x.LastName == y.LastName;
    }

    public int GetHashCode(Person obj)
    {
        return obj.FirstName.GetHashCode() ^ obj.LastName.GetHashCode();
    }
}

public class DistinctCustomComparerExample
{
    public static void Example()
    {
        // Example list of people
        List<Person> people = new List<Person>
        {
            new Person { FirstName = "John", LastName = "Doe" },
            new Person { FirstName = "Jane", LastName = "Doe" },
            new Person { FirstName = "John", LastName = "Doe" }
        };

        // Using Distinct with a custom equality comparer
        var distinctPeople = people.Distinct(new PersonEqualityComparer());

        // Display distinct people
        foreach (var person in distinctPeople)
        {
            Console.WriteLine($"{person.FirstName} {person.LastName}");
        }
    }
}

Imports System
Imports System.Collections.Generic
Imports System.Linq

Public Class Person
	Public Property FirstName() As String
	Public Property LastName() As String
End Class

Public Class PersonEqualityComparer
	Implements IEqualityComparer(Of Person)

	Public Function Equals(ByVal x As Person, ByVal y As Person) As Boolean Implements IEqualityComparer(Of Person).Equals
		Return x.FirstName = y.FirstName AndAlso x.LastName = y.LastName
	End Function

	Public Function GetHashCode(ByVal obj As Person) As Integer Implements IEqualityComparer(Of Person).GetHashCode
		Return obj.FirstName.GetHashCode() Xor obj.LastName.GetHashCode()
	End Function
End Class

Public Class DistinctCustomComparerExample
	Public Shared Sub Example()
		' Example list of people
		Dim people As New List(Of Person) From {
			New Person With {
				.FirstName = "John",
				.LastName = "Doe"
			},
			New Person With {
				.FirstName = "Jane",
				.LastName = "Doe"
			},
			New Person With {
				.FirstName = "John",
				.LastName = "Doe"
			}
		}

		' Using Distinct with a custom equality comparer
		Dim distinctPeople = people.Distinct(New PersonEqualityComparer())

		' Display distinct people
		For Each person In distinctPeople
			Console.WriteLine($"{person.FirstName} {person.LastName}")
		Next person
	End Sub
End Class

using System;
using System.Collections.Generic;
using System.Linq;

public class DistinctValueTypeExample
{
    public static void Example()
    {
        List<int> integers = new List<int> { 1, 2, 2, 3, 4, 4, 5 };

        // Using Distinct to remove duplicates
        var distinctIntegers = integers.Distinct();

        // Display distinct integers
        foreach (var integer in distinctIntegers)
        {
            Console.WriteLine(integer);
        }
    }
}

Imports System
Imports System.Collections.Generic
Imports System.Linq

Public Class DistinctValueTypeExample
	Public Shared Sub Example()
		Dim integers As New List(Of Integer) From {1, 2, 2, 3, 4, 4, 5}

		' Using Distinct to remove duplicates
		Dim distinctIntegers = integers.Distinct()

		' Display distinct integers
		For Each [integer] In distinctIntegers
			Console.WriteLine([integer])
		Next [integer]
	End Sub
End Class

using System;
using System.Collections.Generic;
using System.Linq;

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class DistinctAnonymousTypesExample
{
    public static void Example()
    {
        List<Person> people = new List<Person>
        {
            new Person { FirstName = "John", LastName = "Doe" },
            new Person { FirstName = "Jane", LastName = "Doe" },
            new Person { FirstName = "John", LastName = "Doe" }
        };

        // Using Distinct with anonymous types
        var distinctPeople = people
            .Select(p => new { p.FirstName, p.LastName })
            .Distinct();

        // Display distinct anonymous types
        foreach (var person in distinctPeople)
        {
            Console.WriteLine($"{person.FirstName} {person.LastName}");
        }
    }
}

Imports System
Imports System.Collections.Generic
Imports System.Linq

Public Class Person
	Public Property FirstName() As String
	Public Property LastName() As String
End Class

Public Class DistinctAnonymousTypesExample
	Public Shared Sub Example()
		Dim people As New List(Of Person) From {
			New Person With {
				.FirstName = "John",
				.LastName = "Doe"
			},
			New Person With {
				.FirstName = "Jane",
				.LastName = "Doe"
			},
			New Person With {
				.FirstName = "John",
				.LastName = "Doe"
			}
		}

		' Using Distinct with anonymous types
		Dim distinctPeople = people.Select(Function(p) New With {
			Key p.FirstName,
			Key p.LastName
		}).Distinct()

		' Display distinct anonymous types
		For Each person In distinctPeople
			Console.WriteLine($"{person.FirstName} {person.LastName}")
		Next person
	End Sub
End Class

// Ensure to include the MoreLINQ Library
using MoreLinq;
using System;
using System.Collections.Generic;
using System.Linq;

public class Person
{
    public int Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

public class DistinctByExample
{
    public static void Example()
    {
        List<Person> people = new List<Person>
        {
            new Person { Id = 1, FirstName = "John", LastName = "Doe" },
            new Person { Id = 2, FirstName = "Jane", LastName = "Doe" },
            new Person { Id = 1, FirstName = "John", LastName = "Doe" }
        };

        // Using DistinctBy to filter distinct people by Id
        var distinctPeople = people.DistinctBy(p => p.Id);

        // Display distinct people
        foreach (var person in distinctPeople)
        {
            Console.WriteLine($"{person.Id}: {person.FirstName} {person.LastName}");
        }
    }
}

' Ensure to include the MoreLINQ Library
Imports MoreLinq
Imports System
Imports System.Collections.Generic
Imports System.Linq

Public Class Person
	Public Property Id() As Integer
	Public Property FirstName() As String
	Public Property LastName() As String
End Class

Public Class DistinctByExample
	Public Shared Sub Example()
		Dim people As New List(Of Person) From {
			New Person With {
				.Id = 1,
				.FirstName = "John",
				.LastName = "Doe"
			},
			New Person With {
				.Id = 2,
				.FirstName = "Jane",
				.LastName = "Doe"
			},
			New Person With {
				.Id = 1,
				.FirstName = "John",
				.LastName = "Doe"
			}
		}

		' Using DistinctBy to filter distinct people by Id
		Dim distinctPeople = people.DistinctBy(Function(p) p.Id)

		' Display distinct people
		For Each person In distinctPeople
			Console.WriteLine($"{person.Id}: {person.FirstName} {person.LastName}")
		Next person
	End Sub
End Class

using IronPdf;
using System;
using System.Collections.Generic;
using System.Linq;

public class DocumentGenerator
{
    public static void Main()
    {
        // Sample data representing categories
        List<string> categories = new List<string>
        {
            "Technology",
            "Business",
            "Health",
            "Technology",
            "Science",
            "Business",
            "Health"
        };

        // Use LINQ Distinct to filter out duplicate values
        var distinctCategories = categories.Distinct();

        // Generate a distinct elements PDF document for each category
        foreach (var category in distinctCategories)
        {
            GeneratePdfDocument(category);
        }
    }

    private static void GeneratePdfDocument(string category)
    {
        // Create a new PDF document using IronPDF
        IronPdf.HtmlToPdf renderer = new IronPdf.HtmlToPdf();
        PdfDocument pdf = renderer.RenderHtmlAsPdf($"<h1>{category} Report</h1>");

        // Save the PDF to a file
        string pdfFilePath = $"{category}_Report.pdf";
        pdf.SaveAs(pdfFilePath);

        // Display a message with the file path
        Console.WriteLine($"PDF generated successfully. File saved at: {pdfFilePath}");
    }
}

Imports IronPdf
Imports System
Imports System.Collections.Generic
Imports System.Linq

Public Class DocumentGenerator
	Public Shared Sub Main()
		' Sample data representing categories
		Dim categories As New List(Of String) From {"Technology", "Business", "Health", "Technology", "Science", "Business", "Health"}

		' Use LINQ Distinct to filter out duplicate values
		Dim distinctCategories = categories.Distinct()

		' Generate a distinct elements PDF document for each category
		For Each category In distinctCategories
			GeneratePdfDocument(category)
		Next category
	End Sub

	Private Shared Sub GeneratePdfDocument(ByVal category As String)
		' Create a new PDF document using IronPDF
		Dim renderer As New IronPdf.HtmlToPdf()
		Dim pdf As PdfDocument = renderer.RenderHtmlAsPdf($"<h1>{category} Report</h1>")

		' Save the PDF to a file
		Dim pdfFilePath As String = $"{category}_Report.pdf"
		pdf.SaveAs(pdfFilePath)

		' Display a message with the file path
		Console.WriteLine($"PDF generated successfully. File saved at: {pdfFilePath}")
	End Sub
End Class