C# Program to Find Integer Numbers from the List of Objects and Sort them Using LINQ

In this article, we will learn how to write a C# program to find integer numbers from a list of objects and sort them using LINQ. LINQ (Language Integrated Query) is one of C#'s powerful features that enables developers to query data from various sources using a SQL-like syntax. It provides a standard approach for data manipulation and sorting, regardless of the data source.

Problem Statement

We need to extract integer numbers from a heterogeneous list containing different data types (strings, integers, characters) and sort them in ascending order. We'll use LINQ's OfType<T>() method to filter integers and OrderBy() method to sort them.

Syntax

Following is the syntax for the OfType<T>() method

public static IEnumerable<TResult> OfType<TResult>(this IEnumerable source);

Following is the syntax for the OrderBy() method

public static IOrderedEnumerable<TSource> OrderBy<TSource, TKey>(
   this IEnumerable<TSource> source, 
   Func<TSource, TKey> keySelector
);

How It Works

Example

The following example demonstrates how to extract and sort integers from a mixed object list

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

class Program {
   static void Main(string[] args) {
      // Create a list with mixed data types
      List<object> mixedList = new List<object> { 
         "Tutpoints", 100, "LINQ", 18, "50", 20, 'A', 34 
      };
      
      // Filter integers and sort them
      var sortedIntegers = mixedList.OfType<int>().OrderBy(x => x);
      
      Console.WriteLine("Original list contains mixed types:");
      foreach (var item in mixedList) {
         Console.WriteLine($"{item} ({item.GetType().Name})");
      }
      
      Console.WriteLine("\nSorted integer values:");
      foreach (int number in sortedIntegers) {
         Console.WriteLine(number);
      }
   }
}

The output of the above code is

Original list contains mixed types:
Tutpoints (String)
100 (Int32)
LINQ (String)
18 (Int32)
50 (String)
20 (Int32)
A (Char)
34 (Int32)

Sorted integer values:
18
20
34
100

Using Method Chaining

You can chain LINQ methods together for more concise code

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

class Program {
   static void Main(string[] args) {
      List<object> data = new List<object> { 
         "Hello", 25, 3.14, 42, "World", 7, 'X', 99 
      };
      
      // Chain OfType and OrderBy in a single statement
      var result = data.OfType<int>().OrderBy(x => x).ToList();
      
      Console.WriteLine("Extracted and sorted integers:");
      Console.WriteLine(string.Join(", ", result));
      
      // Also show count
      Console.WriteLine($"Total integers found: {result.Count}");
   }
}

The output of the above code is

Extracted and sorted integers:
7, 25, 42, 99
Total integers found: 4

Key Methods Used

Conclusion

LINQ's OfType<int>() method efficiently filters integer values from heterogeneous collections, while OrderBy() sorts them in ascending order. This approach provides a clean, readable solution for extracting and organizing specific data types from mixed object collections using method chaining.