update at 2020-06-16 18:18:40 by ehlxr

This commit is contained in:
ehlxr 2020-06-16 18:18:40 +08:00
parent 4c9a6dec3c
commit 939f409503

View File

@ -331,15 +331,15 @@ fn main() {
let v: Vec<_> = counter.into_iter().map(|x| x + 1).collect();
println!("{:?}", v);
let v: Vec<_> = Counter::new()
.zip(Counter::new().skip(1))
.map(|(a, b)| a * b)
.collect();
.zip(Counter::new().skip(1))
.map(|(a, b)| a * b)
.collect();
println!("{:?}", v);
let sum: u32 = Counter::new()
.zip(Counter::new().skip(1))
.map(|(a, b)| a * b)
.filter(|x| x % 3 == 0)
.sum();
.zip(Counter::new().skip(1))
.map(|(a, b)| a * b)
.filter(|x| x % 3 == 0)
.sum();
println!("{}", sum);
// ---------------------------
@ -409,7 +409,7 @@ fn main() {
leaf.parent.borrow().upgrade(),
);
} // -> 离开作用域此时Rc<branch> 的强引用strong_count为 0但是 Weak<branch> 弱引用数weak_count仍然为 1引用 Weak<branch> 的 Rc<leaf> 仍然存在),
// weak_count 无需计数为 0 就能使 Rc<branch> 实例被清理。
// weak_count 无需计数为 0 就能使 Rc<branch> 实例被清理。
println!(
"leaf strong = {}, weak = {}, parent = {:?}",
Rc::strong_count(&leaf),
@ -937,7 +937,7 @@ fn main() {
println!("{}", s);
let mut s: String = "Hello".to_string();
let w = "World";
s.push_str(w);// 并不需要获取 w 的所有权
s.push_str(w); // 并不需要获取 w 的所有权
s.push('!');
println!("{} {}", s, w);
@ -948,18 +948,21 @@ fn main() {
let s1 = String::from("Hello, ");
let s2 = String::from("World!");
let s3 = s1 + &s2; // 注意 s1 被移动了,不能继续使用
// println!("{} {} {}", s1, s3, s2);
// println!("{} {} {}", s1, s3, s2);
println!("{} {}", s3, s2);
for c in "नमˑे".chars() {
println!("{}", c);
let hello = "测试中文字符串";
for c in hello.chars() {
print!("{} ", c);
}
for b in "नमˑे".bytes() {
println!("{}", b);
println!("");
for b in hello.bytes() {
print!("{} ", b);
}
let hello = "Здравствуйте";
let s = &hello[0..4];
println!("&hello[0..4]={}", s);
println!("");
// let s = hello[1]; // Rust 的字符串不支持索引
// let s = &hello[0..4]; // thread 'main' panicked at 'byte index 4 is not a char boundary; it is inside '试' (bytes 3..6) of `测试中文字符串`', src/libcore/str/mod.rs:2219:5
print!("{}", &hello[0..3]);
}
fn test_tuple(t: (i32, &str)) {
@ -1265,9 +1268,9 @@ impl ToString for Tweet {
//}
fn notify<T, U>(t: &T, u: &U) -> String
where
T: Summary + ToString,
U: Summary,
where
T: Summary + ToString,
U: Summary,
{
format!("{}, {}", u.summarize(), t.to_string())
}
@ -1335,18 +1338,18 @@ fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
}
struct Cacher<T, D, F>
where
T: Fn(&D) -> F,
where
T: Fn(&D) -> F,
{
calculation: T,
value: HashMap<D, F>,
}
impl<T, D, F> Cacher<T, D, F>
where
D: Hash + Eq,
F: Copy,
T: Fn(&D) -> F,
where
D: Hash + Eq,
F: Copy,
T: Fn(&D) -> F,
{
fn new(calculation: T) -> Cacher<T, D, F> {
Self {
@ -1406,10 +1409,10 @@ struct Shoe {
fn shoes_in_my_size(shoes: Vec<Shoe>, shoe_size: u32) -> Vec<Shoe> {
shoes
// .iter() // a collection of type `std::vec::Vec<Shoe>` cannot be built from `std::iter::Iterator<Item=&Shoe>`
.into_iter() //获取 vector 所有权的迭代器
.filter(|s| s.size == shoe_size)
.collect()
// .iter() // a collection of type `std::vec::Vec<Shoe>` cannot be built from `std::iter::Iterator<Item=&Shoe>`
.into_iter() //获取 vector 所有权的迭代器
.filter(|s| s.size == shoe_size)
.collect()
}
struct Counter {