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struct T {
    iterm1: i32,
    iterm2: i32,
}

fn test_fn((a, b): (i32, i32)) {
    println!("{} {}", a, b);
}

fn main() {
    let tuple = (1i32, 2i32);
    let (first, second) = tuple;
    let callable = |(a, b): (i32, i32)| {
        println!("{} {}", a, b);
    };
    println!("{} {}", first, second);
    test_fn(tuple);
    callable(tuple);

    let t = T {
        iterm1: 1,
        iterm2: 2,
    };

    let T {
        iterm1: i1,
        iterm2: i2,
    } = t;
    println!("{} {}", i1, i2);

    let T { iterm1: ii1, .. } = t;
    println!("{}", ii1);

    let a = 1i32;

    match a {
        0..=1 => println!("a = 1"),
        _ => println!("default"),
    }

    let b = Some(1);
    if let Some(num) = b {
        println!("num = {}", num)
    }


    let arr = vec![1, 2, 3];
    for (index, val) in arr.iter().enumerate() {
        println!("{} => {}", index, val);
    }
}

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    let t = 1; // 1 2 3 有效
    match t {
        1 => println!(" is 1"),
        2 => println!(" is 2"),
        3 => println!(" is 3"),
        _ => println!(" is default"),
    }

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fn main() {
    let t = 1; // 1 2 3 有效
    match t {
        i if i > 2 => println!(" bigger than 2"),
        _ => println!(" is default"),
    }
}

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fn main() {
    let t = Some(Some(3)); // 1 2 3 有效
    match t {
        Some(r @ Some(1..=3)) => println!("{:?}", r),
        _ => println!(" is default"),
    }

    let mut x: Option<String> = Some("hello".into());
    match &mut x {
        Some(s) => s.push_str("world"),
        None => println!("none"),
    }

    println!("{}", x.unwrap())

    let x = 5i32;
    match x {
        ref r => println!("{}", r),
    }

    let mut y = 6i32;

    match y {
        ref mut r => *r = 5i32,
    }

    println!("{}", y)
}