C# Program to return a collection with repeated elements

To return a collection with repeated elements in C#, use the Enumerable.Repeat method from the System.Linq namespace. This method creates a sequence that contains one repeated value a specified number of times.

Syntax

Following is the syntax for Enumerable.Repeat method −

public static IEnumerable<TResult> Repeat<TResult>(TResult element, int count)

Parameters

• element − The value to be repeated in the result sequence.

• count − The number of times to repeat the value in the generated sequence.

Return Value

Returns an IEnumerable<T> that contains a repeated value.

Using Enumerable.Repeat with Numbers

Example

using System;
using System.Linq;

class Demo {
   static void Main() {
      // repeating element 50, two times
      var num = Enumerable.Repeat(50, 2);
      
      // displaying repeating elements
      foreach (int ele in num) {
         Console.WriteLine(ele);
      }
   }
}

The output of the above code is −

50
50

Using Enumerable.Repeat with Strings

Example

using System;
using System.Linq;

class Demo {
   static void Main() {
      // repeating string "Hello", three times
      var greetings = Enumerable.Repeat("Hello", 3);
      
      // displaying repeating elements
      foreach (string greeting in greetings) {
         Console.WriteLine(greeting);
      }
   }
}

The output of the above code is −

Hello
Hello
Hello

Using Enumerable.Repeat with Custom Objects

Example

using System;
using System.Linq;

class Student {
   public string Name { get; set; }
   public int Age { get; set; }
   
   public override string ToString() {
      return $"Name: {Name}, Age: {Age}";
   }
}

class Demo {
   static void Main() {
      Student student = new Student { Name = "John", Age = 20 };
      
      // repeating the same student object, four times
      var students = Enumerable.Repeat(student, 4);
      
      // displaying repeating elements
      foreach (Student s in students) {
         Console.WriteLine(s);
      }
   }
}

The output of the above code is −

Name: John, Age: 20
Name: John, Age: 20
Name: John, Age: 20
Name: John, Age: 20

Converting to Array or List

Example

using System;
using System.Linq;

class Demo {
   static void Main() {
      // create array from repeated elements
      int[] repeatedArray = Enumerable.Repeat(25, 5).ToArray();
      Console.WriteLine("Array: " + string.Join(", ", repeatedArray));
      
      // create list from repeated elements
      var repeatedList = Enumerable.Repeat("C#", 3).ToList();
      Console.WriteLine("List count: " + repeatedList.Count);
      
      foreach (string item in repeatedList) {
         Console.WriteLine(item);
      }
   }
}

The output of the above code is −

Array: 25, 25, 25, 25, 25
List count: 3
C#
C#
C#

Conclusion

The Enumerable.Repeat method in C# provides an efficient way to create collections with repeated elements. It works with any data type and can be easily converted to arrays or lists using ToArray() and ToList() methods.