198 lines
3.2 KiB
Markdown
198 lines
3.2 KiB
Markdown
1.
|
||
|
||
```rust
|
||
fn main() {
|
||
let s: &str = "hello, world";
|
||
}
|
||
```
|
||
|
||
2.
|
||
|
||
```rust
|
||
fn main() {
|
||
let s: Box<str> = "hello, world".into();
|
||
greetings(&s)
|
||
}
|
||
|
||
fn greetings(s: &str) {
|
||
println!("{}",s)
|
||
}
|
||
```
|
||
|
||
```rust
|
||
fn main() {
|
||
let s: Box<&str> = "hello, world".into();
|
||
greetings(*s)
|
||
}
|
||
|
||
fn greetings(s: &str) {
|
||
println!("{}", s);
|
||
}
|
||
```
|
||
|
||
3.
|
||
|
||
```rust
|
||
fn main() {
|
||
let mut s = String::new();
|
||
s.push_str("hello, world");
|
||
s.push('!');
|
||
|
||
assert_eq!(s, "hello, world!");
|
||
}
|
||
```
|
||
|
||
4.
|
||
|
||
```rust
|
||
fn main() {
|
||
let mut s = String::from("hello");
|
||
s.push(',');
|
||
s.push_str(" world");
|
||
s += "!";
|
||
|
||
println!("{}", s)
|
||
}
|
||
```
|
||
|
||
5.
|
||
|
||
```rust
|
||
fn main() {
|
||
let s = String::from("I like dogs");
|
||
// Allocate new memory and store the modified string there
|
||
let s1 = s.replace("dogs", "cats");
|
||
|
||
assert_eq!(s1, "I like cats")
|
||
}
|
||
```
|
||
|
||
6.
|
||
|
||
```rust
|
||
fn main() {
|
||
let s1 = String::from("hello,");
|
||
let s2 = String::from("world!");
|
||
let s3 = s1.clone() + &s2;
|
||
assert_eq!(s3,"hello,world!");
|
||
println!("{}",s1);
|
||
}
|
||
```
|
||
|
||
7.
|
||
|
||
```rust
|
||
fn main() {
|
||
let s = "hello, world".to_string();
|
||
greetings(s)
|
||
}
|
||
|
||
fn greetings(s: String) {
|
||
println!("{}",s)
|
||
}
|
||
```
|
||
|
||
```rust
|
||
fn main() {
|
||
let s = String::from("hello, world");
|
||
greetings(s)
|
||
}
|
||
|
||
fn greetings(s: String) {
|
||
println!("{}",s)
|
||
}
|
||
```
|
||
|
||
8.
|
||
|
||
```rust
|
||
fn main() {
|
||
let s = "hello, world".to_string();
|
||
let s1: &str = &s;
|
||
}
|
||
```
|
||
|
||
```rust
|
||
fn main() {
|
||
let s = "hello, world";
|
||
let s1: &str = s;
|
||
}
|
||
```
|
||
|
||
```rust
|
||
fn main() {
|
||
let s = "hello, world".to_string();
|
||
let s1: String = s;
|
||
}
|
||
```
|
||
|
||
9.
|
||
|
||
```rust
|
||
fn main() {
|
||
// You can use escapes to write bytes by their hexadecimal values
|
||
// fill the blank below to show "I'm writing Rust"
|
||
let byte_escape = "I'm writing Ru\x73\x74!";
|
||
println!("What are you doing\x3F (\\x3F means ?) {}", byte_escape);
|
||
|
||
// ...or Unicode code points.
|
||
let unicode_codepoint = "\u{211D}";
|
||
let character_name = "\"DOUBLE-STRUCK CAPITAL R\"";
|
||
|
||
println!("Unicode character {} (U+211D) is called {}",
|
||
unicode_codepoint, character_name );
|
||
|
||
let long_string = "String literals
|
||
can span multiple lines.
|
||
The linebreak and indentation here \
|
||
can be escaped too!";
|
||
println!("{}", long_string);
|
||
}
|
||
```
|
||
|
||
10.
|
||
|
||
```rust
|
||
fn main() {
|
||
let raw_str = "Escapes don't work here: \x3F \u{211D}";
|
||
// modify above line to make it work
|
||
assert_eq!(raw_str, "Escapes don't work here: ? ℝ");
|
||
|
||
// If you need quotes in a raw string, add a pair of #s
|
||
let quotes = r#"And then I said: "There is no escape!""#;
|
||
println!("{}", quotes);
|
||
|
||
// If you need "# in your string, just use more #s in the delimiter.
|
||
// You can use up to 65535 #s.
|
||
let delimiter = r###"A string with "# in it. And even "##!"###;
|
||
println!("{}", delimiter);
|
||
|
||
// Fill the blank
|
||
let long_delimiter = r###"Hello, "##""###;
|
||
assert_eq!(long_delimiter, "Hello, \"##\"")
|
||
}
|
||
```
|
||
|
||
11.
|
||
|
||
```rust
|
||
fn main() {
|
||
let s1 = String::from("hi,中国");
|
||
let h = &s1[0..1];
|
||
assert_eq!(h, "h");
|
||
|
||
let h1 = &s1[3..6];
|
||
assert_eq!(h1, "中");
|
||
}
|
||
```
|
||
|
||
12.
|
||
|
||
```rust
|
||
fn main() {
|
||
for c in "你好，世界".chars() {
|
||
println!("{}", c)
|
||
}
|
||
}
|
||
```
|