fn main() {
    const MAX_POINTS:u32 = 100;
    println!("常量max_points:{}",MAX_POINTS);
    let x = 5;
    println!("x is {}",x);
    // shadowing 影藏x的不可变特性  变成一个变量
    let x = x + 1;
    let x = x * 2;
    println!("x is {}",x);

    let spaces = "  ";
    let spaces = spaces.len();
    println!("{}",spaces)

}

fn main() {
   let guess:u32 = "42".parse().expect("not a number");
   println!("{}",guess)
}

fn main() {
    let tup: (i32,f64,u8) = (500,6.4,1);
    println!("{}, {}, {} ",tup.0,tup.1,tup.2);
}

let months = ["Jan","Feb"];
    let a : [i32;5] = [1,2,3,4,5];

fn main() {
   println!("main function");
   otherFunction(5,6)
}

fn otherFunction(x:i32, y:i32) {
   println!("other function value:{} {}",x,y);
}

fn plus_five(x:i32) -> i32 {
   return x + 5;
}

fn main() {
   let x = plus_five(6);
   println!("x :{}",x)
}

fn main() {
   let number = 3;
   if number < 5  {
      println!("small")
   } else {
      println!("big")
   }
}

fn main() {
   let condition = true;
   let number = if condition {5} else {6};
   println!("number:{}",number)
}

fn main() {
   let mut counter = 0;
   let result = loop {
      counter +=1;
      if counter == 10 {
         break counter * 2;
      }
   };
   println!("result:{}",result)
}

fn main() {
   let a = [10,20,30,40,50];
   for element in a.iter() {
      println!("element is {}",element)
   }
}

fn main() {
   for number in (1..11).rev() {
      println!("{}",number);
   }
}