Control Flow, Methods, Parameters, and Scope

Conditionals and Loops

if (score >= 90)
{
    Console.WriteLine("Excellent");
}
else if (score >= 75)
{
    Console.WriteLine("Good");
}
else
{
    Console.WriteLine("Needs improvement");
}

for (int i = 0; i < 5; i++)
{
    Console.WriteLine(i);
}

C# offers familiar control-flow constructs, but readability and intent remain more important than syntax alone.

Methods

static int Add(int a, int b)
{
    return a + b;
}

Methods should have focused responsibilities and meaningful names. Clear method boundaries make code easier to test and reuse.

Parameter Types

C# supports value parameters, optional parameters, named arguments, ref, out, and params. Beginners should start with value parameters and then learn the advanced forms with care.

static void PrintUser(string name, int age = 18)
{
    Console.WriteLine($"{name} is {age}");
}

Switch and Pattern Matching Basics

string message = score switch
{
    >= 90 => "Excellent",
    >= 75 => "Good",
    _ => "Keep working"
};

Modern C# uses expressive switch expressions and pattern matching, which make many decision structures cleaner than long chains of if-else logic.

Scope and Lifetime

Variables exist only within their scope. Understanding block scope and method scope helps students avoid confusion about reuse, side effects, and accidental shadowing.

Real-World Usage Snapshot

Control flow and method design shape every application, from web APIs and services to desktop tools and automation scripts. Good method design is one of the earliest markers of clean code.