Rust by Example

if/else

Branching with if-else is similar to other languages. Unlike many of them, the boolean condition doesn't need to be surrounded by parentheses, and each condition is followed by a block. if-else conditionals are expressions, and, all branches must return the same type.

fn main() {

let n = 5;

if n < 0 {

print!("{} is negative", n);

} else if n > 0 {

print!("{} is positive", n);

} else {

print!("{} is zero", n);

}

let big_n =

if n < 10 && n > -10 {

println!(", and is a small number, increase ten-fold");

// This expression returns an `i32`.

10 * n

} else {

println!(", and is a big number, halve the number");

// This expression must return an `i32` as well.

n / 2

// TODO ^ Try suppressing this expression with a semicolon.

};

//   ^ Don't forget to put a semicolon here! All `let` bindings need it.

println!("{} -> {}", n, big_n);

}

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