Conditions: if and switch
Branching with if/else, the ternary operator, and modern switch expressions with patterns.
if / else if / else
if (temp >= 30)
{
Console.WriteLine("hot");
}
else if (temp >= 20)
{
Console.WriteLine("warm");
}
else
{
Console.WriteLine("cool");
}
Conditions are bool — never a number. Order matters: the first true branch wins, so ranges must descend (checking >= 20 before >= 30 would misclassify). Braces even for one line: future-you adds a second line and the indentation lie becomes a bug.
Ternary: conditional expressions
string label = score >= 50 ? "pass" : "fail";
int max = a > b ? a : b;
condition ? whenTrue : whenFalse is an expression — it produces a value. Use it for simple choices; nested ternaries are where readability goes to die.
switch expressions with patterns
static string Grade(int score) => score switch
{
>= 90 => "A",
>= 80 => "B",
>= 70 => "C",
>= 0 => "F",
_ => "invalid"
};
A switch expression matches the subject against patterns — here relational patterns (>= 90) — and yields the value after =>. Arms are tried top to bottom; _ is the catch-all. Compared with an if-chain: each arm is a value, the compiler warns when you miss cases it can prove (for enums), and ranges read as data, not control flow. Both forms are idiomatic; switch expressions shine for classification.