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Displaying a Hollow Rectangle with Border Symbols in C#

In this C# program, the user is prompted to enter a symbol, a width, and a height. The program then generates and displays a hollow rectangle using that symbol for the outer border, while the interior of the rectangle remains empty (represented by spaces). The outer border is created using the symbol entered by the user, while the inner space is left empty, creating a hollow effect.

The rectangle is built such that:

The first and last rows are completely filled with the symbol.

The middle rows have the symbol only at the beginning and end, leaving spaces in between.

This exercise demonstrates how to use loops to generate and format output in C#, and it also introduces the concept of creating simple graphical patterns in the console.



Group

C# Flow Control Basics

Objective

Write a C# program that prompts for a symbol, a width, and a height, and displays a hollow rectangle of that width and height, using that symbol for the outer border, as in this example:

Enter a symbol: 4
Enter the desired width: 3
Enter the desired height: 5

444
4 4
4 4
4 4
444

Example C# Exercise

 Copy C# Code 
using System;

namespace HollowRectangle
{
    class Program
    {
        static void Main(string[] args)
        {
            // Prompt the user to enter a symbol
            Console.Write("Enter a symbol: ");
            char symbol = Console.ReadKey().KeyChar;  // Read the symbol entered by the user
            Console.WriteLine(); // Move to the next line

            // Prompt the user to enter the desired width
            Console.Write("Enter the desired width: ");
            int width = int.Parse(Console.ReadLine());  // Read the width of the rectangle

            // Prompt the user to enter the desired height
            Console.Write("Enter the desired height: ");
            int height = int.Parse(Console.ReadLine()); // Read the height of the rectangle

            // Generate the hollow rectangle
            for (int i = 0; i < height; i++)
            {
                if (i == 0 || i == height - 1)
                {
                    // Print the full line for the top and bottom borders
                    for (int j = 0; j < width; j++)
                    {
                        Console.Write(symbol);
                    }
                }
                else
                {
                    // Print the hollow part for the middle rows
                    Console.Write(symbol); // Print the left border
                    for (int j = 1; j < width - 1; j++)
                    {
                        Console.Write(" "); // Print spaces for the hollow part
                    }
                    Console.Write(symbol); // Print the right border
                }

                Console.WriteLine(); // Move to the next line after printing one row
            }
        }
    }
}

 Output

//Example 1 (User Inputs: symbol = 4, width = 3, height = 5):
Enter a symbol: 4
Enter the desired width: 3
Enter the desired height: 5

444
4 4
4 4
4 4
444

//Example 2 (User Inputs: symbol = *, width = 6, height = 4):
Enter a symbol: *
Enter the desired width: 6
Enter the desired height: 4

******
*    *
*    *
******

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More C# Practice Exercises of C# Flow Control Basics

Explore our set of C# Practice Exercises! Specifically designed for beginners, these exercises will help you develop a solid understanding of the basics of C#. From variables and data types to control structures and simple functions, each exercise is crafted to challenge you incrementally as you build confidence in coding in C#.