C#: Display the upper triangular of a given matrix

Last update on August 22 2025 12:42:28 (UTC/GMT +8 hours)

Write a C# Sharp program to print or display an upper triangular matrix.

Sample Solution:-

C# Sharp Code:

using System;

public class Exercise27  
{  
    public static void Main()
    {
        int i, j, n;
        int[,] arr1 = new int[50, 50];

        // Prompt user for the size of the square matrix
        Console.Write("\n\nDisplay the upper triangular of a given matrix :\n");
        Console.Write("----------------------------------------------\n");
        Console.Write("Input the size of the square matrix : ");
        n = Convert.ToInt32(Console.ReadLine());

        // Input elements into the matrix
        Console.Write("Input elements in the first matrix :\n");
        for (i = 0; i < n; i++)
        {
            for (j = 0; j < n; j++)
            {
                Console.Write("element - [{0}],[{1}] : ", i, j);
                arr1[i, j] = Convert.ToInt32(Console.ReadLine());
            }
        }  

        // Display the input matrix
        Console.Write("The matrix is :\n");
        for (i = 0; i < n; i++)
        {
            for (j = 0; j < n; j++)
                Console.Write("{0}  ", arr1[i, j]);

            Console.Write("\n");
        }

        // Display the upper triangular matrix by setting non-upper triangular elements to zero
        Console.Write("\nSetting zero in upper triangular matrix\n");
        for (i = 0; i < n; i++)
        {
            Console.Write("\n");
            for (j = 0; j < n; j++)
            {
                if (i >= j)
                    Console.Write("{0}  ", arr1[i, j]); // Display upper triangular elements
                else
                    Console.Write("{0}  ", 0); // Display zero for non-upper triangular elements
            }
        }

        Console.Write("\n\n");
    }   
}

Sample Output:

Display the upper triangular of a given matrix :                                                              
----------------------------------------------                                                                
Input the size of the square matrix : 3                                                                       
Input elements in the first matrix :                                                                          
element - [0],[0] : 1                                                                                         
element - [0],[1] : 2                                                                                         
element - [0],[2] : 3                                                                                         
element - [1],[0] : 4                                                                                         
element - [1],[1] : 5                                                                                         
element - [1],[2] : 6                                                                                         
element - [2],[0] : 7                                                                                         
element - [2],[1] : 8                                                                                         
element - [2],[2] : 9                                                                                         
The matrix is :                                                                                               
1  2  3                                                                                                       
4  5  6                                                                                                       
7  8  9                                                                                                       
                                                                                                              
Setting zero in upper triangular matrix 

1  0  0                                                                                                       
4  5  0                                                                                                       
7  8  9

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