else if

Goal of This Episode

Use else if to handle multiple condition branches — not just two-way choices, but three-way, four-way, and beyond.

Main Text

The if...else... from last episode only handles “pick one of two.” But what if there are more cases? Say, letter grades: A, B, C, F… That’s when you need else if.

Example: Letter Grades

fn main() {
    let score = 85;

    if score >= 90 {
        println!("A");
    } else if score >= 80 {
        println!("B");
    } else if score >= 70 {
        println!("C");
    } else {
        println!("F");
    }
}

How Does It Decide?

Rust goes from top to bottom, checking the conditions one by one:

1. score >= 90? Is 85 >= 90? No, skip.
2. score >= 80? Is 85 >= 80? Yes! Print "B", then stop.
3. Everything after that is never looked at.

This is important: as soon as one condition holds, all the rest are skipped.

Try Other Scores

• score = 95 → prints "A".
• score = 73 → prints "C".
• score = 50 → prints "F" (nothing above holds, so it falls through to else).

The Structure

if condition1 {
    ...
} else if condition2 {
    ...
} else if condition3 {
    ...
} else {
    ... (when none of the above holds)
}

You can have as many else ifs as you like. The final else is optional (though it’s usually a good idea to include it, in case some situation slips through).

Recap

• else if handles multiple condition branches — more than just two-way choices.
• Rust checks conditions from top to bottom; the first one that holds gets executed, and all the rest are skipped.
• The final else is optional; it handles the case where “none of the above holds.”