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Basic Syntax and Structure

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In this section, we will cover the fundamental syntax and structure of C# programs. Understanding these basics is crucial for writing and reading C# code effectively.

Key Concepts

  1. Namespaces
  2. Classes
  3. Main Method
  4. Statements and Expressions
  5. Comments
  6. Indentation and Code Blocks

  1. Namespaces

Namespaces are used to organize code and prevent naming conflicts. They are declared using the namespace keyword.

namespace MyFirstNamespace
{
    // Classes, interfaces, structs, enums, and delegates go here
}

Namespaces can be nested and are typically used to group related classes.

  1. Classes

Classes are the building blocks of C# programs. They define the properties and methods that objects created from the class can use.

namespace MyFirstNamespace
{
    class MyClass
    {
        // Fields, properties, methods, and events go here
    }
}

  1. Main Method

The Main method is the entry point of a C# application. It is where the program starts execution.

namespace MyFirstNamespace
{
    class Program
    {
        static void Main(string[] args)
        {
            // Code to be executed goes here
            Console.WriteLine("Hello, World!");
        }
    }
}

  1. Statements and Expressions

Statements are complete instructions that perform actions. Expressions are constructs that evaluate to a value.

Example of Statements:

int x = 5; // Declaration statement
x = x + 2; // Assignment statement
Console.WriteLine(x); // Method call statement

Example of Expressions:

int y = 3 + 4; // Expression: 3 + 4
bool isTrue = (y > 5); // Expression: y > 5

  1. Comments

Comments are used to explain code and are ignored by the compiler. C# supports single-line and multi-line comments.

Single-line Comment:

// This is a single-line comment
Console.WriteLine("Hello, World!");

Multi-line Comment:

/*
 This is a multi-line comment
 that spans multiple lines
*/
Console.WriteLine("Hello, World!");

  1. Indentation and Code Blocks

Proper indentation and code blocks improve code readability. Code blocks are defined using curly braces {}.

Example:

namespace MyFirstNamespace
{
    class Program
    {
        static void Main(string[] args)
        {
            if (true)
            {
                Console.WriteLine("This is a code block.");
            }
        }
    }
}

Practical Example

Let's put all these concepts together in a simple program:

using System;

namespace BasicSyntaxExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Declare a variable
            int number = 10;

            // Use an if statement
            if (number > 5)
            {
                // Print a message to the console
                Console.WriteLine("Number is greater than 5");
            }

            // Use a loop
            for (int i = 0; i < number; i++)
            {
                Console.WriteLine("i = " + i);
            }
        }
    }
}

Explanation:

  1. Namespace: BasicSyntaxExample groups the Program class.
  2. Class: Program contains the Main method.
  3. Main Method: Entry point of the program.
  4. Variable Declaration: int number = 10;
  5. If Statement: Checks if number is greater than 5.
  6. Loop: Prints values from 0 to 9.

Exercises

Exercise 1: Simple Program

Write a C# program that declares a variable, assigns it a value, and prints the value to the console.

using System;

namespace Exercise1
{
    class Program
    {
        static void Main(string[] args)
        {
            // Your code here
        }
    }
}

Solution:

using System;

namespace Exercise1
{
    class Program
    {
        static void Main(string[] args)
        {
            // Declare and assign a variable
            int myNumber = 42;

            // Print the variable to the console
            Console.WriteLine("The value of myNumber is: " + myNumber);
        }
    }
}

Exercise 2: Conditional Statement

Write a C# program that checks if a number is even or odd and prints the result.

using System;

namespace Exercise2
{
    class Program
    {
        static void Main(string[] args)
        {
            // Your code here
        }
    }
}

Solution:

using System;

namespace Exercise2
{
    class Program
    {
        static void Main(string[] args)
        {
            // Declare and assign a variable
            int number = 15;

            // Check if the number is even or odd
            if (number % 2 == 0)
            {
                Console.WriteLine("The number is even.");
            }
            else
            {
                Console.WriteLine("The number is odd.");
            }
        }
    }
}

Summary

In this section, we covered the basic syntax and structure of C# programs, including namespaces, classes, the Main method, statements, expressions, comments, and code blocks. We also provided practical examples and exercises to reinforce these concepts. Understanding these basics is essential for progressing to more advanced topics in C#.

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