// ❌ It won't compilefnis_palindrome(str:String)->bool{// lp rp// | |// v → ← v// str = "aabbccbbaa"letmutlp=0;letmutrp=str.len() -1;whilelp < rp {ifstr[lp] !=str[rp] {// ^^^ `String` cannot be indexed by `usize`returnfalse; } lp +=1; rp -=1; }true...
("example 3"); let mut str1 = String::from("hello"); //error[E0277]: the type `std::string::String` cannot be indexed by `{integer}` // --> src/main.rs:59:23 // | //59 | let answer = &str1[0]; // | ^^^ `std::string::String` cannot be indexed by `{integer...
String到&str:as_str(),as_ref(),Deref,&x[..] 适用于OsStr和CStr的类似(可能有损)方法 这些转换中的大多数在性能上是等效的,Rust社区似乎对哪些是“正确的”存在分歧。 我最终习惯于根据上下文使用不同的字符串(例如into(),表示要将a &str转换为a,String以便可以将其返回,to_owned()表示稍后将拥有该字...
$cargo runCompiling collections v0.1.0 (file:///projects/collections) error[E0277]: the type `String` cannot be indexed by `{integer}`-->src/main.rs:3:13| 3 | let h = s1[0]; | ^^^ `String` cannot be indexed by `{integer}` | = help: the trait `Index<{integer}>` is not...
error[E0277]: the type `str` cannot be indexed by `{integer}` --> src/main.rs:20:10 | 20 | let c = s[0]; | ^^^ string indices are ranges of `usize` | = help: the trait `std::slice::SliceIndex<str>` is not implemented for `{integer}` =...
println!("{}", s1[1]); // error[E0277]: the type `String` cannot be indexed by `{integer}` 1. 2. 上面报错的原因是因为,UTF-8 是不定长编码,但是String的实现是基于 Vec<u8> 的封装的,数组中每一个元素都是一个字节,但UT...
用非usize类型索引的话会给出类似如下的错误: error: the trait bound `collections::vec::Vec<_> : core::ops::Index<i32>` is not satisfied [E0277] v[j]; ^~~~ note: the type `collections::vec::Vec<_>` cannot be indexed by `i32` ...
error[E0596]: cannot borrow `*row` as mutable, as it is behind a `&` reference From the error, I can see that the issue is that Row should be mutable so I can edit it (which makes sense, since I am mutating it's String). I can't figure out a) how to be able to mutate ...
/// Data must be immutable but not aliasable. This kind of borrow /// cannot currently be expressed by the user and is used only in /// implicit closure bindings. It is needed when you the closure /// is borrowing or mutating a mutable referent, e.g.:...
This problem cannot be solved generally. If the value can be cloned, here is a not-so-specific solution: #[derive(Clone)] struct A{} impl A { fn consume(self) -> usize { 0 } } fn main() { let a = Some(A{}); match a{ Some(ref y) if y.clone().consume() > 0 => {...