This commit is contained in:
sunface 2022-04-09 19:32:12 +08:00
commit b669929771
2 changed files with 37 additions and 37 deletions

View File

@ -6,10 +6,10 @@
fn main() { fn main() {
let x = 5; let x = 5;
// fill the blank // Fill the blank
let p = __; let p = __;
println!("the memory address of x is {:p}", p); // one possible output: 0x16fa3ac84 println!("the memory address of x is {:p}", p); // One possible output: 0x16fa3ac84
} }
``` ```
@ -20,23 +20,23 @@ fn main() {
let x = 5; let x = 5;
let y = &x; let y = &x;
// modify this line only // Modify this line only
assert_eq!(5, y); assert_eq!(5, y);
println!("Success!") println!("Success!");
} }
``` ```
3. ๐ŸŒŸ 3. ๐ŸŒŸ
```rust,editable ```rust,editable
// fix error // Fix error
fn main() { fn main() {
let mut s = String::from("hello, "); let mut s = String::from("hello, ");
borrow_object(s); borrow_object(s);
println!("Success!") println!("Success!");
} }
fn borrow_object(s: &String) {} fn borrow_object(s: &String) {}
@ -45,13 +45,13 @@ fn borrow_object(s: &String) {}
4. ๐ŸŒŸ 4. ๐ŸŒŸ
```rust,editable ```rust,editable
// fix error // Fix error
fn main() { fn main() {
let mut s = String::from("hello, "); let mut s = String::from("hello, ");
push_str(s); push_str(s);
println!("Success!") println!("Success!");
} }
fn push_str(s: &mut String) { fn push_str(s: &mut String) {
@ -65,16 +65,16 @@ fn push_str(s: &mut String) {
fn main() { fn main() {
let mut s = String::from("hello, "); let mut s = String::from("hello, ");
// fill the blank to make it work // Fill the blank to make it work
let p = __; let p = __;
p.push_str("world"); p.push_str("world");
println!("Success!") println!("Success!");
} }
``` ```
#### ref #### Ref
`ref` can be used to take references to a value, similar to `&`. `ref` can be used to take references to a value, similar to `&`.
6. ๐ŸŒŸ๐ŸŒŸ๐ŸŒŸ 6. ๐ŸŒŸ๐ŸŒŸ๐ŸŒŸ
@ -84,18 +84,18 @@ fn main() {
let c = 'ไธญ'; let c = 'ไธญ';
let r1 = &c; let r1 = &c;
// fill the blank๏ผŒdont change other code // Fill the blank๏ผŒdont change other code
let __ r2 = c; let __ r2 = c;
assert_eq!(*r1, *r2); assert_eq!(*r1, *r2);
// check the equality of the two address strings // Check the equality of the two address strings
assert_eq!(get_addr(r1),get_addr(r2)); assert_eq!(get_addr(r1),get_addr(r2));
println!("Success!") println!("Success!");
} }
// get memory address string // Get memory address string
fn get_addr(r: &char) -> String { fn get_addr(r: &char) -> String {
format!("{:p}", r) format!("{:p}", r)
} }
@ -105,8 +105,8 @@ fn get_addr(r: &char) -> String {
7. ๐ŸŒŸ 7. ๐ŸŒŸ
```rust,editable ```rust,editable
// remove something to make it work // Remove something to make it work
// don't remove a whole line ! // Don't remove a whole line !
fn main() { fn main() {
let mut s = String::from("hello"); let mut s = String::from("hello");
@ -115,21 +115,21 @@ fn main() {
println!("{}, {}", r1, r2); println!("{}, {}", r1, r2);
println!("Success!") println!("Success!");
} }
``` ```
#### Mutablity #### Mutability
8. ๐ŸŒŸ Error: Borrow a immutable object as mutable 8. ๐ŸŒŸ Error: Borrow an immutable object as mutable
```rust,editable ```rust,editable
fn main() { fn main() {
//fix error by modifying this line // Fix error by modifying this line
let s = String::from("hello, "); let s = String::from("hello, ");
borrow_object(&mut s); borrow_object(&mut s);
println!("Success!") println!("Success!");
} }
fn borrow_object(s: &mut String) {} fn borrow_object(s: &mut String) {}
@ -138,7 +138,7 @@ fn borrow_object(s: &mut String) {}
9. ๐ŸŒŸ๐ŸŒŸ Ok: Borrow a mutable object as immutable 9. ๐ŸŒŸ๐ŸŒŸ Ok: Borrow a mutable object as immutable
```rust,editable ```rust,editable
// this code has no errors! // This code has no errors!
fn main() { fn main() {
let mut s = String::from("hello, "); let mut s = String::from("hello, ");
@ -146,7 +146,7 @@ fn main() {
s.push_str("world"); s.push_str("world");
println!("Success!") println!("Success!");
} }
fn borrow_object(s: &String) {} fn borrow_object(s: &String) {}
@ -156,7 +156,7 @@ fn borrow_object(s: &String) {}
10. ๐ŸŒŸ๐ŸŒŸ 10. ๐ŸŒŸ๐ŸŒŸ
```rust,editable ```rust,editable
// comment one line to make it work // Comment one line to make it work
fn main() { fn main() {
let mut s = String::from("hello, "); let mut s = String::from("hello, ");
@ -178,8 +178,8 @@ fn main() {
let r1 = &mut s; let r1 = &mut s;
let r2 = &mut s; let r2 = &mut s;
// add one line below to make a compiler error: cannot borrow `s` as mutable more than once at a time // Add one line below to make a compiler error: cannot borrow `s` as mutable more than once at a time
// you can't use r1 and r2 at the same time // You can't use r1 and r2 at the same time
} }
``` ```

View File

@ -4,7 +4,7 @@
```rust,editable ```rust,editable
fn main() { fn main() {
// use as many approaches as you can to make it work // Use as many approaches as you can to make it work
let x = String::from("hello, world"); let x = String::from("hello, world");
let y = x; let y = x;
println!("{},{}",x,y); println!("{},{}",x,y);
@ -39,7 +39,7 @@ fn main() {
// Only modify the code below! // Only modify the code below!
fn give_ownership() -> String { fn give_ownership() -> String {
let s = String::from("hello, world"); let s = String::from("hello, world");
// convert String to Vec // Convert String to Vec
let _s = s.into_bytes(); let _s = s.into_bytes();
s s
} }
@ -47,7 +47,7 @@ fn give_ownership() -> String {
4. ๐ŸŒŸ๐ŸŒŸ 4. ๐ŸŒŸ๐ŸŒŸ
```rust,editable ```rust,editable
// fix the error without removing code line // Fix the error without removing code line
fn main() { fn main() {
let s = String::from("hello, world"); let s = String::from("hello, world");
@ -63,7 +63,7 @@ fn print_str(s: String) {
5. ๐ŸŒŸ๐ŸŒŸ 5. ๐ŸŒŸ๐ŸŒŸ
```rust, editable ```rust, editable
// don't use clone ,use copy instead // Don't use clone ,use copy instead
fn main() { fn main() {
let x = (1, 2, (), "hello".to_string()); let x = (1, 2, (), "hello".to_string());
let y = x.clone(); let y = x.clone();
@ -80,12 +80,12 @@ Mutability can be changed when ownership is transferred.
fn main() { fn main() {
let s = String::from("hello, "); let s = String::from("hello, ");
// modify this line only ! // Modify this line only !
let s1 = s; let s1 = s;
s1.push_str("world"); s1.push_str("world");
println!("Success!") println!("Success!");
} }
``` ```
@ -95,13 +95,13 @@ fn main() {
fn main() { fn main() {
let x = Box::new(5); let x = Box::new(5);
let ... // implement this line, dont change other lines! let ... // Implement this line, dont change other lines!
*y = 4; *y = 4;
assert_eq!(*x, 5); assert_eq!(*x, 5);
println!("Success!") println!("Success!");
} }
``` ```
@ -148,7 +148,7 @@ fn main() {
let _s = t.0; let _s = t.0;
// modify this line only, don't use `_s` // Modify this line only, don't use `_s`
println!("{:?}", t); println!("{:?}", t);
} }
``` ```
@ -159,7 +159,7 @@ fn main() {
fn main() { fn main() {
let t = (String::from("hello"), String::from("world")); let t = (String::from("hello"), String::from("world"));
// fill the blanks // Fill the blanks
let (__, __) = __; let (__, __) = __;
println!("{:?}, {:?}, {:?}", s1, s2, t); // -> "hello", "world", ("hello", "world") println!("{:?}, {:?}, {:?}", s1, s2, t); // -> "hello", "world", ("hello", "world")