163 lines
3.6 KiB
Rust
163 lines
3.6 KiB
Rust
fn main() {
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let guess: u32 = "42".parse().expect("Not a number!");
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println!("You guessed: {}", guess);
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let heart_eyed_cat = '😻';
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println!("{}", heart_eyed_cat);
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let cc = another_function(3, 'a');
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println!("The value of cc is: {}", cc);
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// Statements and Expressions
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let x = {
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let y = 5;
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y + 1
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};
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println!("The value of x is: {}", x);
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for number in 1..4 {
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println!("{}!", number);
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}
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let result = fibonacci_function(3);
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println!("The result is: {}", result);
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// 相互转换摄氏与华氏温度
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let celsius = 30.0;
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let fahrenheit = celsius_to_fahrenheit(celsius);
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println!("{} celsius is {} fahrenheit.", celsius, fahrenheit);
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let fahrenheit = 86.0;
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let celsius = fahrenheit_to_celsius(fahrenheit);
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println!("{} fahrenheit is {} celsius.", fahrenheit, celsius);
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let mut s = String::from("hello");
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s.push_str(", world!");
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println!("{}", s);
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let s2 = s;
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println!("{}", s2);
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// println!("{}", s);
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let t = String::from("hello");
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takes_ownership(t);
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// println!("{}", t);
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let y = 5;
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makes_copy(y);
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println!("{}", y);
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let s4 = String::from("hello");
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let len = calculate_length(&s4);
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println!("The length of '{}' is {}.", s4, len);
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// let s5 = String::from("hello");
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// change(&s5);
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let mn = String::from("hello world");
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let word = first_word(&mn);
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// mn.clear();
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println!("The first word is: {}", word);
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// let width1 = 30;
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// let height1 = 50;
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let rect1 = Rectangle {
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width: 30,
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height: 50,
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};
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dbg!(&rect1);
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// println!("rect1 is {:#?}", rect1);
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// println!(
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// "The area of the rectangle is {} square pixels.",
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// area(&rect1)
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// );
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println!(
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"The area of the rectangle is {} square pixels.",
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rect1.area()
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);
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let rect2 = Rectangle::square(3);
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println!(
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"The area of the rectangle is {} square pixels.",
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rect2.area()
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);
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}
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fn another_function(a: i32, char: char) -> i32 {
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println!("Another function.");
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println!("The value of a is: {}", a);
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println!("The value of char is: {}", char);
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5
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}
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fn fibonacci_function(n: i32) -> i32 {
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if n == 0 {
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return 0;
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} else if n == 1 {
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return 1;
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} else {
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return fibonacci_function(n - 1) + fibonacci_function(n - 2);
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}
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}
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fn celsius_to_fahrenheit(celsius: f64) -> f64 {
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celsius * 1.8 + 32.0
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}
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fn fahrenheit_to_celsius(fahrenheit: f64) -> f64 {
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(fahrenheit - 32.0) / 1.8
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}
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fn takes_ownership(some_string: String) {
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// some_string 进入作用域
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println!("{some_string}");
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} // 这里，some_string 移出作用域并调用 `drop` 方法。
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// 占用的内存被释放
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fn makes_copy(some_integer: i32) {
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// some_integer 进入作用域
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println!("{some_integer}");
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} // 这里，some_integer 移出作用域。没有特殊之处
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fn calculate_length(s: &String) -> usize {
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s.len()
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}
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// fn change(some_string: &String) {
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// some_string.push_str(", world");
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// }
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fn first_word(s: &String) -> &str {
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let bytes = s.as_bytes();
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for (i, &item) in bytes.iter().enumerate() {
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if item == b' ' {
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return &s[..i];
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}
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}
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&s[..]
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}
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// fn area(width: u32, height: u32) -> u32 {
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// width * height
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// }
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#[derive(Debug)]
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struct Rectangle {
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width: u32,
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height: u32,
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}
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impl Rectangle {
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fn area(&self) -> u32 {
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self.width * self.height
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}
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}
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impl Rectangle {
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fn square(size: u32) -> Rectangle {
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Rectangle {
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width: size,
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height: size,
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}
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}
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}
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