在使用 闭包+move后 数值类型的变量仍然可以引用，但是string变量不能再引用，提示已经“value borrowed here after move”，从这里可以引申，其它引用类型如struct 应该跟string一样处理。
pub fn main(){
let ch='英';
let ch2=& ch;
let ch3=& ch;
println!("{:?}",(&ch,ch2,ch3));
let ch=String::from("英");
let ch2=&ch;
let ch3=& ch;
println!("{:?}",(&ch,ch2,ch3));
let mut b = false;
let x = &mut b;
{
let mut c = || { *x = true; };
// The following line is an error:
// let y = &x;
c();
println!("{:?}",x);
}
let z = &x;
//b=true;
println!("{:?}",z);
let mut num = 5;
let add_num = || println!("Closure num:{:?}",num);
add_num();
let a=&mut num;
println!("num:{:?}",&num);
let mut add_num = || {num+=5;println!("Closure num:{:?}",&num);};
add_num();
println!("num:{:?}",&num);
let a=&mut num;
println!("num:{:?}",a);
let mut add_num = move ||{num+=5;println!("Closure num:{:?}",&num);};
add_num();
println!("num:{:?}",&num);
let a=&mut num;
println!("num:{:?}",a);
let mut num = String::from("hello");
let add_num = || println!("Closure num:{:?}",num);
add_num();
let a=&mut num;
println!("num:{:?}",&num);
let mut add_num = || {num+="5";println!("Closure num:{:?}",&num);};
add_num();
println!("num:{:?}",&num);
let a=&mut num;
println!("num:{:?}",a);
let mut add_num = move || {num+="5";println!("Closure num:{:?}",&num);};
add_num();
//let a=&mut num; // ^^^^^^^^ value borrowed here after move
//println!("num:{:?}",a);
}