Question

我正在玩纸牌游戏，想画一张纸牌。我有一个random_choice()函数，它会随机选择一个i32并将其用作切片。它没有执行预期的操作，而是说切片必须是usize。

我尝试将i32转换为u16，然后转换为usize，但是那也不起作用。我还尝试将i32直接转换为usize。

这些是我的数据集的结构：

struct Card {
    Attack: i32,
    Defense: i32,
    Cost: i32,
    Pay: i32,
    Name: String,
    Type: String,
    Effect: String,
}

struct Deck {
    Cards: Vec<Card>,
}

以下是功能：

fn random_choice_deck(deck: Deck) -> Card {
    let slice = rand::thread_rng().gen_range(i32::from(0), i32::from(deck.Cards.len()));
    return deck.Cards[usize::from(u16::from(slice))];
}
fn Draw_Cards(deck: Deck) {
    let cards = vec![
        random_choice(deck),
        random_choice(deck),
        random_choice(deck),
    ];
    for a in cards {
        println!(
            "{} : C{}, A{}, D{}, P{}",
            a.Name, a.Cost, a.Attack, a.Defense, a.Pay
        );
    }
}

输出应该是套牌中的东西。例如，我有自己的飞机甲板：

Cards: vec![
    wildcat, wildcat, wildcat, wildcat, zero, zero, zero, flying_gun, flying_gun,
]

里面的东西：

let mut wildcat = Card {
    Attack: i32::from(10),
    Defense: i32::from(50),
    Name: String::from("Wildcat"),
    Type: String::from("Air"),
    Effect: String::from("None"),
    Cost: i32::from(25),
    Pay: i32::from(50),
};
let mut zero = Card {
    Attack: i32::from(20),
    Defense: i32::from(35),
    Name: String::from("A6M Zero"),
    Type: String::from("Air"),
    Effect: String::from("Air only"),
    Cost: i32::from(25),
    Pay: i32::from(50),
};
let mut flying_gun = Card {
    Attack: i32::from(5),
    Defense: i32::from(1),
    Name: String::from("Flying Gun"),
    Type: String::from("Air"),
    Effect: String::from("None"),
    Cost: i32::from(5),
    Pay: i32::from(5),
};

它应该输出wildcat，zero或flying_gun，但它会输出以下错误：

error[E0277]: the trait bound `u16: std::convert::From<i32>` is not satisfied

return deck.Cards[usize::from(u16::from(slice))
                              ^^^^^^^^^ the trait 'std::convert::From<i32>' is not implemented for 'u16'

更改i32以使用

0 个答案: