rust学习(二)

play on line  

match if  

#![allow(unused)]
fn write_bar(size: u64){
    match size{
        o if o < 100 => println!("{:?} less than 100", o),
        o if o < 200 && o > 100  => println!("{:?} between 100-200", o),
        _ => println!("{:?} bigger than 200", size),
    }
}
fn main() {
    write_bar(10);
    write_bar(150);
    write_bar(250);
}

 println!("{:#?}", 1)

#[derive(Debug)]
struct Teacher<'a> {
    name: &'a str,
    age1: u8
}

#[derive(Debug)]
struct Person<'a> {
    name: &'a str,
    age: u8
}

fn main() {
    let name = "Peter";
    let mut age = 27;
    let peter = Person { name, age };
    
    age = 22;
    let lilei = Teacher{ name:"Lilei", age1:age};
    // 美化打印
    println!("{:#?}", lilei);
    println!("{:#?}", peter);
}

 println! with param

#[derive(Debug)]
struct Complex { real: f32, imag: f32 }

fn main() {
    println!("The big range is {big:#?} and the small is {small}",
             small = 0,
             big = &[1, 2]);
    println!("Debug: {:#?}", Complex{real: 2.2, imag: 7.2});
}

 try! 宏和 ? 一样

write!(f, "{}", value)?; 
try!(write!(f, "{}", value));

闭包

|val| val + x，　输入和返回类型两者都可以自动推导，而输入变量 名必须指明。

• 声明时使用 || 替代 () 将输入参数括起来。
• 函数体定界符（{}）对于单个表达式是可选的，其他情况必须加上。
• 有能力捕获外部环境的变量。

fn function (i: i32) -> i32 { i + 1 }
let closure_annotated = |i: i32| -> i32 { i + 1 };

　　

valgrind 也可以检查rust的内存泄露

Drop trait 包含在 prelude 中，所以无需导入它。