Conditionals

Making Decisions in Zig

If / Else

Zig's if statement is straightforward. No parentheses around the condition, and braces are mandatory:

if (x > 10) {
    std.debug.print("big\n", .{});
} else if (x > 5) {
    std.debug.print("medium\n", .{});
} else {
    std.debug.print("small\n", .{});
}

Note that Zig does require parentheses around the condition, unlike Go. This is one area where Zig follows C tradition.

If as an Expression

One of Zig's powerful features is that if can be used as an expression, not just a statement. This means if can return a value:

const label = if (x > 10) "big" else "small";

This is similar to the ternary operator in C (? :), but more readable. The else branch is mandatory when using if as an expression.

If with Optionals

Zig has a special if syntax for unwrapping optional values:

const maybe_value: ?i32 = 42;
if (maybe_value) |value| {
    std.debug.print("got: {}\n", .{value});
} else {
    std.debug.print("no value\n", .{});
}

The |value| syntax captures the unwrapped non-null value. This eliminates null pointer errors at compile time.

Switch

Zig's switch is an expression, which means it always produces a value. It is exhaustive: you must handle every possible case or provide an else branch:

const result = switch (day) {
    .monday => "start of the week",
    .friday => "almost weekend",
    else => "regular day",
};

Switch on integers:

const label = switch (score) {
    0...59 => "fail",
    60...79 => "pass",
    80...100 => "excellent",
    else => "invalid",
};

The ... syntax defines an inclusive range. This is unique to Zig and makes range matching concise and clear.

Switch vs If-Else Chains

"The needs of the many outweigh the needs of the few." --- Spock's logic applies to conditionals too: switch serves the many cases elegantly, while if-else handles the few complex ones.

Use switch when you have multiple discrete values or ranges to match against. Use if-else chains when conditions are complex expressions that do not map cleanly to a single value.

Your Task

Write a function classifyTemp that takes an i32 temperature in Celsius and returns a []const u8 string:

• "freezing" if temp <= 0
• "cold" if temp <= 15
• "warm" if temp <= 30
• "hot" if temp > 30