Lernen Set Operations and Use Cases | Sets and Collection Utilities

Understanding set operations is essential for many programming tasks. In mathematics, a set is a collection of distinct elements. Sets support special operations based on set theory, such as union, intersection, and difference. In C#, the HashSet<T> class provides these operations through built-in methods.

Union combines all unique elements from two sets;
Intersection finds elements that are present in both sets;
Difference returns elements that are in one set but not the other.

You use these operations to compare or merge data efficiently, making them powerful tools for collection management in C#.

Program.cs


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using System;
using System.Collections.Generic;

namespace ConsoleApp
{
    public class Program
    {
        public static void Main(string[] args)
        {
            HashSet<string> setA = new HashSet<string> { "apple", "banana", "cherry" };
            HashSet<string> setB = new HashSet<string> { "banana", "date", "elderberry" };

            // Union
            HashSet<string> unionSet = new HashSet<string>(setA);
            unionSet.UnionWith(setB);
            Console.WriteLine("Union:");
            foreach (var item in unionSet)
            {
                Console.WriteLine(item);
            }

            // Intersection
            HashSet<string> intersectionSet = new HashSet<string>(setA);
            intersectionSet.IntersectWith(setB);
            Console.WriteLine("\nIntersection:");
            foreach (var item in intersectionSet)
            {
                Console.WriteLine(item);
            }
        }
    }
}

Set operations are especially useful in many real-world scenarios. You can use sets to remove duplicates from a collection, ensuring that each element appears only once. Sets also help you find common elements between two collections, such as identifying users who appear in two different mailing lists. By leveraging set operations, you can write cleaner and more efficient code to solve these common problems.

Program.cs


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using System;
using System.Collections.Generic;

namespace ConsoleApp
{
    public class Program
    {
        public static void Main(string[] args)
        {
            HashSet<string> groupA = new HashSet<string> { "Alice", "Bob", "Charlie" };
            HashSet<string> groupB = new HashSet<string> { "Bob", "Diana", "Eve" };

            // Find names in groupA but not in groupB
            HashSet<string> differenceSet = new HashSet<string>(groupA);
            differenceSet.ExceptWith(groupB);

            Console.WriteLine("Names in groupA but not in groupB:");
            foreach (var name in differenceSet)
            {
                Console.WriteLine(name);
            }
        }
    }
}

1. What does the `IntersectWith` method do?

2. When would you use a set instead of a list?

3. Fill in the blanks to find unique elements in two `HashSet<int>`:

War alles klar?

Danke für Ihr Feedback!

Abschnitt 3. Kapitel 2

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Suggested prompts:

Can you show me example code for these set operations in C#?

What are some other practical uses for set operations in programming?

How do set operations in C# compare to those in other languages?

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Union combines all unique elements from two sets;
Intersection finds elements that are present in both sets;
Difference returns elements that are in one set but not the other.

You use these operations to compare or merge data efficiently, making them powerful tools for collection management in C#.

Program.cs


              123456789101112131415161718192021222324252627282930313233
            
using System;
using System.Collections.Generic;

namespace ConsoleApp
{
    public class Program
    {
        public static void Main(string[] args)
        {
            HashSet<string> setA = new HashSet<string> { "apple", "banana", "cherry" };
            HashSet<string> setB = new HashSet<string> { "banana", "date", "elderberry" };

            // Union
            HashSet<string> unionSet = new HashSet<string>(setA);
            unionSet.UnionWith(setB);
            Console.WriteLine("Union:");
            foreach (var item in unionSet)
            {
                Console.WriteLine(item);
            }

            // Intersection
            HashSet<string> intersectionSet = new HashSet<string>(setA);
            intersectionSet.IntersectWith(setB);
            Console.WriteLine("\nIntersection:");
            foreach (var item in intersectionSet)
            {
                Console.WriteLine(item);
            }
        }
    }
}

Program.cs


              12345678910111213141516171819202122232425
            
using System;
using System.Collections.Generic;

namespace ConsoleApp
{
    public class Program
    {
        public static void Main(string[] args)
        {
            HashSet<string> groupA = new HashSet<string> { "Alice", "Bob", "Charlie" };
            HashSet<string> groupB = new HashSet<string> { "Bob", "Diana", "Eve" };

            // Find names in groupA but not in groupB
            HashSet<string> differenceSet = new HashSet<string>(groupA);
            differenceSet.ExceptWith(groupB);

            Console.WriteLine("Names in groupA but not in groupB:");
            foreach (var name in differenceSet)
            {
                Console.WriteLine(name);
            }
        }
    }
}

1. What does the `IntersectWith` method do?

2. When would you use a set instead of a list?

3. Fill in the blanks to find unique elements in two `HashSet<int>`:

War alles klar?

Danke für Ihr Feedback!

Abschnitt 3. Kapitel 2

Set Operations and Use Cases

1. What does the IntersectWith method do?

2. When would you use a set instead of a list?

3. Fill in the blanks to find unique elements in two HashSet<int>:

Set Operations and Use Cases

1. What does the IntersectWith method do?

2. When would you use a set instead of a list?

3. Fill in the blanks to find unique elements in two HashSet<int>:

1. What does the `IntersectWith` method do?

3. Fill in the blanks to find unique elements in two `HashSet<int>`:

1. What does the `IntersectWith` method do?

3. Fill in the blanks to find unique elements in two `HashSet<int>`: