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1.实例化需要初始化全部成员变量2.如果需要实例化对象可变#xff0c;加上mut则所有成员变量均可变 Rust支持通过已实例化的对象#xff0c;赋值给未赋值的对象的成员变量 #![allow(warnings)]
use std::io;
use std::error::Error;
use std::boxed::Box;
use s…Rust struct
1.实例化需要初始化全部成员变量2.如果需要实例化对象可变加上mut则所有成员变量均可变 Rust支持通过已实例化的对象赋值给未赋值的对象的成员变量 #![allow(warnings)]
use std::io;
use std::error::Error;
use std::boxed::Box;
use std::convert::TryInto;
use std::cmp::Ordering;
use std::cmp::min;
use std::cmp::max;struct User {name: String,age: i32
}fn main() - Result(), Boxdyn Error {let u: User User {name: String::from(sqs),age: 12};print!({} {} , u.name, u.age);let b: User User {name: String::from(sqssqs),..u};print!({} {}, b.name, b.age);Ok(())
}定义结构体中的方法 #![allow(warnings)]
use std::io;
use std::error::Error;
use std::boxed::Box;
use std::convert::TryInto;
use std::cmp::Ordering;
use std::cmp::min;
use std::cmp::max;struct User {name: String,age: i32
}impl User {fn print(self) {println!({} {}, self.name, self.age);}
}fn main() - Result(), Boxdyn Error {let u: User User {name: String::from(sqs),age: 12};u.print();let b: User User {name: String::from(sqssqs),..u};b.print();Ok(())
}修改成员变量 #![allow(warnings)]
use std::io;
use std::error::Error;
use std::boxed::Box;
use std::convert::TryInto;
use std::cmp::Ordering;
use std::cmp::min;
use std::cmp::max;struct User {name: String,age: i32
}fn main() - Result(), Boxdyn Error {let mut u: User User {name: String::from(sqs),age: 12};print!({} {} , u.name, u.age);u.name String::from(sqssqs);u.age 16;print!({} {}, u.name, u.age);Ok(())
}通过 借用 修改成员变量 #![allow(warnings)]
use std::io;
use std::error::Error;
use std::boxed::Box;
use std::convert::TryInto;
use std::cmp::Ordering;
use std::cmp::min;
use std::cmp::max;struct User {name: String,age: i32
}fn chageAge(u : mut User){u.age 10;
}fn main() - Result(), Boxdyn Error {let mut u: User User {name: String::from(sqs),age: 12};println!({} {}, u.name, u.age);u.name String::from(sqssqs);u.age 16;println!({} {}, u.name, u.age);chageAge(mut u);println!({} {}, u.name, u.age);Ok(())
}通过 转移所有权 修改成员变量 #![allow(warnings)]
use std::io;
use std::error::Error;
use std::boxed::Box;
use std::convert::TryInto;
use std::cmp::Ordering;
use std::cmp::min;
use std::cmp::max;struct User {name: String,age: i32
}fn chageAge(mut u: User) - User {u.age 10;u
}fn main() - Result(), Boxdyn Error {let mut u: User User {name: String::from(sqs),age: 12};println!({} {}, u.name, u.age);u.name String::from(sqssqs);u.age 16;println!({} {}, u.name, u.age);u chageAge(u);println!({} {}, u.name, u.age);Ok(())
}以下代码报错
#![allow(warnings)]
use std::io;
use std::error::Error;
use std::boxed::Box;
use std::convert::TryInto;
use std::cmp::Ordering;
use std::cmp::min;
use std::cmp::max;struct User {name: String,age: i32
}fn chageAge(mut u: User) - User {u.age 10;u
}fn main() - Result(), Boxdyn Error { let mut u: User User {name: String::from(sqs),age: 12};println!({} {}, u.name, u.age);u.name String::from(sqssqs);u.age 16;println!({} {}, u.name, u.age);let b: User chageAge(u);println!({} {}, u.name, u.age);Ok(())
}报错详情
编译出错
error[E0382]: borrow of moved value: u.age-- /main.rs:30:31|
21 | let mut u: User User {| ----- move occurs because u has type User, which does not implement the Copy trait
...
29 | let b: User chageAge(u);| - value moved here
30 | println!({} {}, u.name, u.age);| ^^^^^ value borrowed here after move| note: this error originates in the macro $crate::format_args_nl which comes from the expansion of the macro println (in Nightly builds, run with -Z macro-backtrace for more info)error: aborting due to previous errorFor more information about this error, try rustc --explain E0382.原因
所有权已经从u给b导致u无法使用
