149 lines
3.0 KiB
Markdown
149 lines
3.0 KiB
Markdown
1.
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```rust
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fn main() {
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println!("{0}, this is {1}. {1}, this is {0}", "Alice", "Bob");// => Alice, this is Bob. Bob, this is Alice
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assert_eq!(format!("{1}{0}", 1, 2), "21");
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assert_eq!(format!("{1}{}{0}{}", 1, 2), "2112");
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println!("Success!")
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}
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```
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2.
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```rust
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fn main() {
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println!("{argument}", argument = "test"); // => "test"
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assert_eq!(format!("{name}{}", 1, name = 2), "21");
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assert_eq!(format!("{a} {c} {b}",a = "a", b = 'b', c = 3 ), "a 3 b");
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// named argument must be placed after other arguments
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println!("{abc} {0}", 2, abc = "def");
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println!("Success!")
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}
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```
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3.
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```rust
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fn main() {
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// the following two are padding with 5 spaces
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println!("Hello {:5}!", "x"); // => "Hello x !"
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println!("Hello {:1$}!", "x", 5); // => "Hello x !"
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assert_eq!(format!("Hello {1:0$}!", 5, "x"), "Hello x !");
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assert_eq!(format!("Hello {:width$}!", "x", width = 5), "Hello x !");
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println!("Success!")
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}
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```
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4.
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```rust
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fn main() {
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// left align
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println!("Hello {:<5}!", "x"); // => Hello x !
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// right align
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assert_eq!(format!("Hello {:>5}!", "x"), "Hello x!");
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// center align
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assert_eq!(format!("Hello {:^5}!", "x"), "Hello x !");
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// left align, pad with '&'
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assert_eq!(format!("Hello {:&<5}!", "x"), "Hello x&&&&!");
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println!("Success!")
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}
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```
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5.
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```rust
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fn main() {
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println!("Hello {:5}!", 5); // => Hello 5!
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println!("Hello {:+}!", 5); // => Hello +5!
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println!("Hello {:05}!", 5); // => Hello 00005!
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println!("Hello {:05}!", -5); // => Hello -0005!
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assert!(format!("{number:0>width$}", number=1, width=6) == "000001");
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println!("Success!")
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}
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```
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6.
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```rust
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fn main() {
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let v = 3.1415926;
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println!("{:.1$}", v, 4); // same as {:.4} => 3.1416
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assert_eq!(format!("{:.2}", v), "3.14");
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assert_eq!(format!("{:+.2}", v), "+3.14");
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assert_eq!(format!("{:.0}", v), "3");
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println!("Success!")
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}
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```
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7.
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```rust
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fn main() {
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let s = "Hello, world!";
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println!("{0:.5}", s); // => Hello
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assert_eq!(format!("Hello {1:.0$}!", 3, "abcdefg"), "Hello abc!");
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println!("Success!")
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}
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```
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8.
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```rust
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fn main() {
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assert_eq!(format!("{:#b}", 27), "0b11011");
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assert_eq!(format!("{:#o}", 27), "0o33");
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assert_eq!(format!("{:#x}", 27), "0x1b");
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assert_eq!(format!("{:#X}", 27), "0x1B");
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println!("{:x}!", 27); // hex with no prefix => 1b
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println!("{:#010b}", 27); // pad binary with 0, width = 10, => 0b00011011
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println!("Success!")
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}
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```
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9.
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```rust
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fn get_person() -> String {
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String::from("sunface")
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}
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fn get_format() -> (usize, usize) {
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(4, 1)
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}
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fn main() {
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let person = get_person();
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println!("Hello, {person}!");
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let (width, precision) = get_format();
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let scores = [("sunface", 99.12), ("jack", 60.34)];
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/* Make it print:
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sunface: 99.1
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jack: 60.3
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*/
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for (name, score) in scores {
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println!("{name}: {score:width$.precision$}");
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}
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}
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``` |