The Duck Pond Splash Down

Day 2: Basics of C# – Part 2

Objective: Continue learning the fundamentals of C#.

Topics Covered:

1. Control statements (if, if-else, switch)
2. Loops (for, while, do-while)
3. Introduction to arrays

Topic 1: Control Statements

Control statements are used to make decisions and execute different parts of the code based on certain conditions.

If-Else Statement

Example:

using System;

namespace IfElseDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            int number = 10;

            if (number > 0)
            {
                Console.WriteLine("The number is positive.");
            }
            else if (number < 0)
            {
                Console.WriteLine("The number is negative.");
            }
            else
            {
                Console.WriteLine("The number is zero.");
            }
        }
    }
}

Explanation:

• if (number > 0) – Checks if the number is positive.
• else if (number < 0) – Checks if the number is negative.
• else – Executes if the number is zero.

Switch Statement

Example:

using System;

namespace SwitchDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            int day = 3;

            switch (day)
            {
                case 1:
                    Console.WriteLine("Monday");
                    break;
                case 2:
                    Console.WriteLine("Tuesday");
                    break;
                case 3:
                    Console.WriteLine("Wednesday");
                    break;
                case 4:
                    Console.WriteLine("Thursday");
                    break;
                case 5:
                    Console.WriteLine("Friday");
                    break;
                case 6:
                    Console.WriteLine("Saturday");
                    break;
                case 7:
                    Console.WriteLine("Sunday");
                    break;
                default:
                    Console.WriteLine("Invalid day");
                    break;
            }
        }
    }
}

Explanation:

• switch (day) – Evaluates the value of day.
• case x: – Executes the code block corresponding to the value of day.
• default: – Executes if none of the cases match.

Topic 2: Loops

Loops are used to execute a block of code repeatedly.

For Loop

Example:

using System;

namespace ForLoopDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i = 1; i <= 5; i++)
            {
                Console.WriteLine("Iteration: " + i);
            }
        }
    }
}

Explanation:

• for (int i = 1; i <= 5; i++) – Initializes i to 1, runs the loop while i is less than or equal to 5, and increments i by 1 after each iteration.

While Loop

Example:

using System;

namespace WhileLoopDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 1;

            while (i <= 5)
            {
                Console.WriteLine("Iteration: " + i);
                i++;
            }
        }
    }
}

Explanation:

• while (i <= 5) – Runs the loop while i is less than or equal to 5.
• i++ – Increments i by 1 after each iteration.

Do-While Loop

Example:

using System;

namespace DoWhileLoopDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 1;

            do
            {
                Console.WriteLine("Iteration: " + i);
                i++;
            } while (i <= 5);
        }
    }
}

Explanation:

• do { ... } while (i <= 5) – Executes the loop body first, then checks the condition. Runs the loop while i is less than or equal to 5.

Topic 3: Introduction to Arrays

Arrays are used to store multiple values in a single variable.

Example:

using System;

namespace ArraysDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] numbers = { 1, 2, 3, 4, 5 };

            for (int i = 0; i < numbers.Length; i++)
            {
                Console.WriteLine("Element at index " + i + ": " + numbers[i]);
            }
        }
    }
}

Explanation:

• int[] numbers = { 1, 2, 3, 4, 5 }; – Declares and initializes an array of integers.
• numbers.Length – Gets the length of the array.
• for (int i = 0; i < numbers.Length; i++) – Iterates through the array elements.

Example Exercise

Write a program to find the largest and smallest numbers in an array.

using System;

namespace ArrayExercise
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] numbers = { 23, 89, 12, 37, 98, 5 };

            int max = numbers[0];
            int min = numbers[0];

            for (int i = 1; i < numbers.Length; i++)
            {
                if (numbers[i] > max)
                {
                    max = numbers[i];
                }

                if (numbers[i] < min)
                {
                    min = numbers[i];
                }
            }

            Console.WriteLine("Largest number: " + max);
            Console.WriteLine("Smallest number: " + min);
        }
    }
}

Explanation:

• Initializes the array numbers.
• Sets max and min to the first element of the array.
• Iterates through the array to find the largest (max) and smallest (min) numbers.

This completes the Day 2 topics for Day 3 click here