Control Flow — if, switch, loops

if / else if / else

int score = 85;

if (score >= 90)
    grade = "A+";
else if (score >= 80)
    grade = "A";
else if (score >= 70)
    grade = "B";
else
    grade = "F";

// Ternary
string status = (age >= 18) ? "Adult" : "Minor";

switch (Classic)

switch (day) {
    case "Mon":
    case "Tue":
        Console.WriteLine("Weekday");
        break;
    case "Sat":
    case "Sun":
        Console.WriteLine("Weekend");
        break;
    default:
        Console.WriteLine("Unknown");
        break;
}

Switch Expression (C# 8+) ⭐

string category = day switch {
    "Mon" or "Tue" or "Wed" or "Thu" or "Fri" => "Weekday",
    "Sat" or "Sun" => "Weekend",
    _ => "Unknown"
};

// Pattern matching
string Describe(object obj) => obj switch {
    int n when n < 0 => "Negative",
    int n => $"Positive {n}",
    string s => $"String: {s}",
    null => "Null",
    _ => "Unknown"
};

Loops

// for
for (int i = 0; i < 10; i++) {
    Console.WriteLine(i);
}

// while
int x = 0;
while (x < 5) {
    Console.WriteLine(x++);
}

// do-while
do {
    input = Console.ReadLine();
} while (input != "exit");

// foreach (collection)
var names = new[] { "Rahim", "Karim", "Sumon" };
foreach (var name in names) {
    Console.WriteLine(name);
}

break, continue

for (int i = 0; i < 10; i++) {
    if (i == 5) break;       // loop শেষ
    if (i % 2 == 0) continue; // পরের iteration
    Console.WriteLine(i);
}