(done) 速通 rustlings(9) 分支跳转

RUST 中的分支跳转-条件判断不需要加括号

fn picky_eater(food: &str) -> &str {
    if food == "strawberry" {
        "Yummy!"
    } else if food == "potato" {
        "I guess I can eat that."
    } else {
        "No thanks!"
    }
}

RUST 作为一种表达式导向的语言，if-else 块作为一个表达式，可以直接赋值给变量：

fn animal_habitat(animal: &str) -> &str {
    // TODO: Fix the compiler error in the statement below.
    let identifier = if animal == "crab" {
        1
    } else if animal == "gopher" {
        2
    } else if animal == "snake" {
        3
    } else {
        4
    };

    // Don't change the expression below!
    if identifier == 1 {
        "Beach"
    } else if identifier == 2 {
        "Burrow"
    } else if identifier == 3 {
        "Desert"
    } else {
        "Unknown"
    }
}