How do I sort a two-dimensional array in C#

Sorting a two-dimensional array in C# can be accomplished using several approaches. The most common methods include sorting individual rows using nested loops with bubble sort, using Array.Sort() for jagged arrays, or converting to a one-dimensional array for sorting.

Syntax

For sorting rows in a 2D array using nested loops −

for (int i = 0; i < arr.GetLength(0); i++) {
   for (int j = 0; j < arr.GetLength(1) - 1; j++) {
      for (int k = 0; k < arr.GetLength(1) - j - 1; k++) {
         if (arr[i, k] > arr[i, k + 1]) {
            // swap elements
         }
      }
   }
}

For sorting jagged arrays using Array.Sort() −

Array.Sort(jaggedArray[rowIndex]);

Using Nested Loops with Bubble Sort

This approach sorts each row of the 2D array individually using the bubble sort algorithm −

using System;

class Program {
   public static void Main() {
      int[,] arr = {
         {64, 34, 25, 12},
         {22, 11, 90, 5},
         {77, 30, 15, 8}
      };

      Console.WriteLine("Original Array:");
      PrintArray(arr);

      // Sort each row
      for (int i = 0; i < arr.GetLength(0); i++) {
         for (int j = 0; j < arr.GetLength(1) - 1; j++) {
            for (int k = 0; k < arr.GetLength(1) - j - 1; k++) {
               if (arr[i, k] > arr[i, k + 1]) {
                  int temp = arr[i, k];
                  arr[i, k] = arr[i, k + 1];
                  arr[i, k + 1] = temp;
               }
            }
         }
      }

      Console.WriteLine("\nSorted Array (each row sorted):");
      PrintArray(arr);
   }

   static void PrintArray(int[,] array) {
      for (int i = 0; i < array.GetLength(0); i++) {
         for (int j = 0; j < array.GetLength(1); j++) {
            Console.Write(array[i, j] + " ");
         }
         Console.WriteLine();
      }
   }
}

The output of the above code is −

Original Array:
64 34 25 12 
22 11 90 5 
77 30 15 8 

Sorted Array (each row sorted):
12 25 34 64 
5 11 22 90 
8 15 30 77 

Using Array.Sort() with Jagged Arrays

For more efficient sorting, convert the 2D array to a jagged array and use Array.Sort() −

using System;

class Program {
   public static void Main() {
      int[][] jaggedArray = {
         new int[] {64, 34, 25, 12},
         new int[] {22, 11, 90, 5},
         new int[] {77, 30, 15, 8}
      };

      Console.WriteLine("Original Jagged Array:");
      PrintJaggedArray(jaggedArray);

      // Sort each row using Array.Sort()
      for (int i = 0; i < jaggedArray.Length; i++) {
         Array.Sort(jaggedArray[i]);
      }

      Console.WriteLine("\nSorted Jagged Array:");
      PrintJaggedArray(jaggedArray);
   }

   static void PrintJaggedArray(int[][] array) {
      for (int i = 0; i < array.Length; i++) {
         for (int j = 0; j < array[i].Length; j++) {
            Console.Write(array[i][j] + " ");
         }
         Console.WriteLine();
      }
   }
}

The output of the above code is −

Original Jagged Array:
64 34 25 12 
22 11 90 5 
77 30 15 8 

Sorted Jagged Array:
12 25 34 64 
5 11 22 90 
8 15 30 77 

Sorting Entire 2D Array as Single Collection

To sort all elements in the 2D array as one collection, flatten it first, sort, then reconstruct −

using System;
using System.Linq;

class Program {
   public static void Main() {
      int[,] arr = {
         {64, 34, 25},
         {22, 11, 90},
         {77, 30, 15}
      };

      Console.WriteLine("Original Array:");
      PrintArray(arr);

      // Flatten, sort, and reconstruct
      int[] flatArray = arr.Cast<int>().OrderBy(x => x).ToArray();
      
      int rows = arr.GetLength(0);
      int cols = arr.GetLength(1);
      int[,] sortedArray = new int[rows, cols];
      
      for (int i = 0; i < rows; i++) {
         for (int j = 0; j < cols; j++) {
            sortedArray[i, j] = flatArray[i * cols + j];
         }
      }

      Console.WriteLine("\nEntire Array Sorted:");
      PrintArray(sortedArray);
   }

   static void PrintArray(int[,] array) {
      for (int i = 0; i < array.GetLength(0); i++) {
         for (int j = 0; j < array.GetLength(1); j++) {
            Console.Write(array[i, j] + " ");
         }
         Console.WriteLine();
      }
   }
}

The output of the above code is −

Original Array:
64 34 25 
22 11 90 
77 30 15 

Entire Array Sorted:
11 15 22 
25 30 34 
64 77 90 

Comparison of Approaches

Conclusion

Sorting two-dimensional arrays in C# can be done row-wise using nested loops or Array.Sort(), or as a complete collection by flattening first. The Array.Sort() method with jagged arrays provides the most efficient solution for sorting individual rows, while LINQ offers a clean approach for sorting all elements together.