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[英]Rust Diesel: the trait bound `NaiveDateTime: Deserialize<'_>` is not satisfied
[英]The trait bound is not satisfied in Rust
我正在嘗試在Rust中編寫一個Tic Tac Toe游戲,但是這個用於更改字段的功能不起作用,我不知道它有什么問題:
fn change_field(mut table: [char; 9], field: i32, player: char) -> bool {
if field > 0 && field < 10 {
if table[field - 1] == ' ' {
table[field - 1] = player;
return true;
} else {
println!("That field isn't empty!");
}
} else {
println!("That field doesn't exist!");
}
return false;
}
我收到這些錯誤:
src/main.rs:16:12: 16:26 error: the trait bound `[char]: std::ops::Index<i32>` is not satisfied [E0277]
src/main.rs:16 if table[field-1] == ' ' {
^~~~~~~~~~~~~~
src/main.rs:16:12: 16:26 help: run `rustc --explain E0277` to see a detailed explanation
src/main.rs:16:12: 16:26 note: slice indices are of type `usize`
src/main.rs:17:13: 17:27 error: the trait bound `[char]: std::ops::Index<i32>` is not satisfied [E0277]
src/main.rs:17 table[field-1] = player;
^~~~~~~~~~~~~~
src/main.rs:17:13: 17:27 help: run `rustc --explain E0277` to see a detailed explanation
src/main.rs:17:13: 17:27 note: slice indices are of type `usize`
src/main.rs:17:13: 17:27 error: the trait bound `[char]: std::ops::IndexMut<i32>` is not satisfied [E0277]
src/main.rs:17 table[field-1] = player;
^~~~~~~~~~~~~~
在Rust的更高版本中,我收到以下錯誤:
error[E0277]: the trait bound `i32: std::slice::SliceIndex<[char]>` is not satisfied
--> src/main.rs:3:12
|
3 | if table[field - 1] == ' ' {
| ^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize`
|
= help: the trait `std::slice::SliceIndex<[char]>` is not implemented for `i32`
= note: required because of the requirements on the impl of `std::ops::Index<i32>` for `[char]`
error[E0277]: the trait bound `i32: std::slice::SliceIndex<[char]>` is not satisfied
--> src/main.rs:4:13
|
4 | table[field - 1] = player;
| ^^^^^^^^^^^^^^^^ slice indices are of type `usize` or ranges of `usize`
|
= help: the trait `std::slice::SliceIndex<[char]>` is not implemented for `i32`
= note: required because of the requirements on the impl of `std::ops::Index<i32>` for `[char]`
這是我在Rust的第一個項目,所以我沒有多少經驗。 我也嘗試將字段更改為u32
。
原因是在筆記中給出的:
note: slice indices are of type `usize`
slice indices are of type `usize` or ranges of `usize`
您需要將i32
值轉換為usize
,例如:
table[(field - 1) as usize]
或者,如果在您的應用程序中有意義,請考慮使用usize
作為field
變量的類型。
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