Mastering Array Traversal and Manipulation in C#

Topic Overview

Welcome to today's session on "Mastering Array Traversal and Manipulation in C#" . Multidimensional arrays are types of arrays that store arrays at each index instead of single elements. Picture it as an 'apartment building' with floors (the outer array) and apartments on each floor (the inner array). Our goal today is to strengthen your foundational knowledge of these 'apartment buildings' and how to handle them effectively in C#.

Creating Multidimensional Arrays

To construct a multidimensional array in C#, we use arrays of arrays. Here are examples to demonstrate how to create and work with 2D static arrays. C# using System; class Solution {public static void Main(string[] args) {// Creating a 2D array int[,] array = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; // Printing the 2D 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();}}} /* Prints: 1 2 3 4 5 6 7 8 9 */

Indexing in Multidimensional Arrays

All indices in C# arrays are 0-based. Let's say you want to visit an apartment on the second floor (index 1) and bring a package to the first unit (index 0) in this building. Here's how you can do it: C# class Solution {public static void Main(string[] args) {int[,] array = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; // Accessing an element Console.WriteLine(array[1, 0]); // Outputs: 4}} We visited the element 4 in the array by its position. The number [1] refers to the second inner array, and [0] refers to the first element of that array.

Finding the Number of Rows and Columns

C# offers various ways to manage multidimensional arrays. For instance, you can determine the number of rows (floors) and columns (units on each floor): C# class Solution {public static void Main(string[] args) {int[,] array = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; // Finding the number of rows int numFloors = array.GetLength(0); Console.WriteLine(numFloors); // Outputs: 3 // Finding the number of columns int numUnits = array.GetLength(1); Console.WriteLine(numUnits); // Outputs: 3}}

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Adding a New Row or Column

To add a new row or column to a 2D static array, create a new array with the desired dimensions, then copy the existing elements into it.

using System;

class Solution {
    public static void Main(string[] args) {
        int[,] array = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        // Create a new array with an additional row
        int[,] newArray = new int[array.GetLength(0) + 1, 3]; // Add 1 more row

        // Copy existing array elements
        for (int i = 0; i < array.GetLength(0); i++) {
            for (int j = 0; j < array.GetLength(1); j++) {
                newArray[i, j] = array[i, j];
            }
        }

        // Add new values to the extra row
        newArray[3, 0] = 10;
        newArray[3, 1] = 11;
        newArray[3, 2] = 12;

        // Display the new array
        for (int i = 0; i < newArray.GetLength(0); i++) {
            for (int j = 0; j < newArray.GetLength(1); j++) {
                Console.Write(newArray[i, j] + " ");
            }
            Console.WriteLine();
        }
    }
}

/*
Prints:
1 2 3
4 5 6
7 8 9
10 11 12
*/

using System;

class Solution {
    public static void Main(string[] args) {
        int[,] array = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        // Create a new array with an additional row
        int[,] newArray = new int[array.GetLength(0) + 1, 3]; // Add 1 more row

        // Copy existing array elements
        for (int i = 0; i < array.GetLength(0); i++) {
            for (int j = 0; j < array.GetLength(1); j++) {
                newArray[i, j] = array[i, j];
            }
        }

        // Add new values to the extra row
        newArray[3, 0] = 10;
        newArray[3, 1] = 11;
        newArray[3, 2] = 12;

        // Display the new array
        for (int i = 0; i < newArray.GetLength(0); i++) {
            for (int j = 0; j < newArray.GetLength(1); j++) {
                Console.Write(newArray[i, j] + " ");
            }
            Console.WriteLine();
        }
    }
}

/*
Prints:
1 2 3
4 5 6
7 8 9
10 11 12
*/

Removing a Row or Column

To remove a row or column from a 2D static array, create a new array with the reduced dimensions and copy over the elements while skipping the one you want to remove.

using System;

class Solution {
    public static void Main(string[] args) {
        int[,] array = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        // Removing the second row (index 1)
        int[,] rowRemovedArray = new int[array.GetLength(0) - 1, array.GetLength(1)]; // New array with 1 less row

        // Copy elements except the second row
        int rowIndex = 0;
        for (int i = 0; i < array.GetLength(0); i++) {
            if (i != 1) { // Skip row 1
                for (int j = 0; j < array.GetLength(1); j++) {
                    rowRemovedArray[rowIndex, j] = array[i, j];
                }
                rowIndex++;
            }
        }

        // Display the new array (with row removed)
        for (int i = 0; i < rowRemovedArray.GetLength(0); i++) {
            for (int j = 0; j < rowRemovedArray.GetLength(1); j++) {
                Console.Write(rowRemovedArray[i, j] + " ");
            }
            Console.WriteLine();
        }
    }
}

/*
Prints:
1 2 3 
7 8 9 
*/

using System;

class Solution {
    public static void Main(string[] args) {
        int[,] array = {
            {1, 2, 3},
            {4, 5, 6},
            {7, 8, 9}
        };

        // Removing the second row (index 1)
        int[,] rowRemovedArray = new int[array.GetLength(0) - 1, array.GetLength(1)]; // New array with 1 less row

        // Copy elements except the second row
        int rowIndex = 0;
        for (int i = 0; i < array.GetLength(0); i++) {
            if (i != 1) { // Skip row 1
                for (int j = 0; j < array.GetLength(1); j++) {
                    rowRemovedArray[rowIndex, j] = array[i, j];
                }
                rowIndex++;
            }
        }

        // Display the new array (with row removed)
        for (int i = 0; i < rowRemovedArray.GetLength(0); i++) {
            for (int j = 0; j < rowRemovedArray.GetLength(1); j++) {
                Console.Write(rowRemovedArray[i, j] + " ");
            }
            Console.WriteLine();
        }
    }
}

/*
Prints:
1 2 3 
7 8 9 
*/

Break/Continue in Nested Loops

Sometimes, when we visit every apartment on each floor, we might need to start visiting the next floor midway. break helps us exit the current loop, while continue helps us skip the current iteration and move to the next one.

class Solution {
    public static void Main(string[] args) {
        string[,] array = {
            {"Apt 101", "Apt 102", "Apt 103"},
            {"Apt 201", "Exit Floor", "Apt 203"},
            {"Apt 301", "Apt 302", "Apt 303"}
        };

        // Break in nested loop
        for (int i = 0; i < array.GetLength(0); i++) {
            for (int j = 0; j < array.GetLength(1); j++) {
                if (array[i, j] == "Exit Floor") {
                    break;
                }
                Console.Write(array[i, j] + ", ");
            }
            Console.WriteLine();
        }
    }
}

/*
Prints:
Apt 101, Apt 102, Apt 103,
Apt 201,
Apt 301, Apt 302, Apt 303,
*/

class Solution {
    public static void Main(string[] args) {
        string[,] array = {
            {"Apt 101", "Apt 102", "Apt 103"},
            {"Apt 201", "Exit Floor", "Apt 203"},
            {"Apt 301", "Apt 302", "Apt 303"}
        };

        // Break in nested loop
        for (int i = 0; i < array.GetLength(0); i++) {
            for (int j = 0; j < array.GetLength(1); j++) {
                if (array[i, j] == "Exit Floor") {
                    break;
                }
                Console.Write(array[i, j] + ", ");
            }
            Console.WriteLine();
        }
    }
}

/*
Prints:
Apt 101, Apt 102, Apt 103,
Apt 201,
Apt 301, Apt 302, Apt 303,
*/

Here, as soon as Exit Floor is found on a floor, the entire loop breaks, and no further units on the floor are visited. However, the other units are processed as before, as break breaks only the nested loop.

We can also make use of continue in a similar scenario:

class Solution {
    public static void Main(string[] args) {
        string[,] array = {
            {"Apt 101", "Apt 102", "Apt 103"},
            {"Apt 201", "Exit Floor", "Apt 203"},
            {"Apt 301", "Apt 302", "Apt 303"}
        };

        // Continue in nested loop
        for (int i = 0; i < array.GetLength(0); i++) {
            for (int j = 0; j < array.GetLength(1); j++) {
                if (array[i, j] == "Exit Floor") {
                    continue;
                }
                Console.Write(array[i, j] + ", ");
            }
            Console.WriteLine();
        }
    }
}

/*
Prints:
Apt 101, Apt 102, Apt 103,
Apt 201, Apt 203,
Apt 301, Apt 302, Apt 303,
*/

class Solution {
    public static void Main(string[] args) {
        string[,] array = {
            {"Apt 101", "Apt 102", "Apt 103"},
            {"Apt 201", "Exit Floor", "Apt 203"},
            {"Apt 301", "Apt 302", "Apt 303"}
        };

        // Continue in nested loop
        for (int i = 0; i < array.GetLength(0); i++) {
            for (int j = 0; j < array.GetLength(1); j++) {
                if (array[i, j] == "Exit Floor") {
                    continue;
                }
                Console.Write(array[i, j] + ", ");
            }
            Console.WriteLine();
        }
    }
}

/*
Prints:
Apt 101, Apt 102, Apt 103,
Apt 201, Apt 203,
Apt 301, Apt 302, Apt 303,
*/

In this case, when Exit Floor is encountered, the continue statement is executed. This skips printing Exit Floor and continues with the next unit on the same floor. The loop doesn't stop entirely but skips over Exit Floor, resulting in a missing apartment in the printout for the second floor.