Conditions And Loops

In modern programming, logic and flow control define how smart your application behaves.
C# has evolved — from simple if statements to pattern-based decisions and expression-style switches.
Let’s explore how decision-making in C# has changed over the years —

if, else if , else

If something is true, do a certain task; otherwise, move on to the next one.

int number = 7;

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

if (score >= 90)
{
    Console.WriteLine("Grade: A");
}
else if (score >= 80)
{
    Console.WriteLine("Grade: B");
}
else
{
    Console.WriteLine("Grade: F");
}

The Ternary Operator ?:

The ternary operator is a shorter way to write simple if...else statements.
It has three parts — a condition, a result if true, and a result if false.

Syntax:

(condition) ? trueResult : falseResult;  

int age = 20;
string message = (age >= 18) ? "Adult" : "Minor";

Console.WriteLine(message); // Output: Adult

switch

A switch statement works just like a long chain of if…else if…else, but it makes your code cleaner and more readable when you need to check multiple possible values of a single variable

int day = 3;

switch (day)
{
    case 1:
        Console.WriteLine("Saturday");
        break;
    case 2:
        Console.WriteLine("Sunday");
        break;
    case 3:
        Console.WriteLine("Monday");
        break;
    default:
        Console.WriteLine("Invalid day");
        break;
}

Important Notes About switch

• Every case must end with a break (to exit the structure).
• The default case works like else in an if statement — it runs when no other case matches.
• In newer versions of C# (from version 8 onward), you can also use the switch expression for cleaner syntax.

int score = 85;

string grade = score switch
{
    >= 90 => "A",
    >= 80 => "B",
    >= 70 => "C",
    _ => "F"
};

Console.WriteLine("Grade: " + grade);

Pattern Matching with switch

Instead of checking only for exact values using case 1: or case “ali”:, you can now use patterns such as:

• Type patterns (checking the data type)
• Range patterns (checking numeric ranges)
• Conditional patterns using when
• Combining multiple cases

Type Pattern

The program checks the type of the variable data and executes the matching case.

object data = "Hello";

switch (data)
{
    case int n:
        Console.WriteLine($"This is a number: {n}");
        break;

    case string s:
        Console.WriteLine($"This is a string: {s}");
        break;

    case bool b:
        Console.WriteLine($"This is a boolean value: {b}");
        break;

    default:
        Console.WriteLine("Unknown type");
        break;
}

Conditional patterns using when

int score = 85;

switch (score)
{
    case int s when s >= 90:
        Console.WriteLine("Excellent");
        break;

    case int s when s >= 70:
        Console.WriteLine("Satisfactory");
        break;

    case int s when s < 70:
        Console.WriteLine("Needs improvement");
        break;

    default:
        Console.WriteLine("Invalid score");
        break;
}