41. Reverse a string
反转字符串
package main import "fmt" func Reverse(s string) string { runes := []rune(s) for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 { runes[i], runes[j] = runes[j], runes[i] } return string(runes) } func main() { input := "The quick brown 狐 jumped over the lazy 犬" fmt.Println(Reverse(input)) // Original string unaltered fmt.Println(input) }
输出
犬 yzal eht revo depmuj 狐 nworb kciuq ehT The quick brown 狐 jumped over the lazy 犬
let t = s.chars().rev().collect::<String>();
or
fn main() { let s = "lorém ipsüm dolör sit amor ❤ "; let t: String = s.chars().rev().collect(); println!("{}", t); }
输出
❤ roma tis rölod müspi mérol
42. Continue outer loop
Print each item v of list a which in not contained in list b. For this, write an outer loop to iterate on a and an inner loop to iterate on b.
打印列表a中不包含在列表b中的每个项目v。 为此，编写一个外部循环来迭代a，编写一个内部循环来迭代b。
package main import "fmt" func printSubtraction(a []int, b []int) { mainloop: for _, v := range a { for _, w := range b { if v == w { continue mainloop } } fmt.Println(v) } } func main() { a := []int{1, 2, 3, 4} b := []int{2, 4, 6, 8} printSubtraction(a, b) }
mainloop is a label used to refer to the outer loop.
输出
1 3
fn main() { let a = ['a', 'b', 'c', 'd', 'e']; let b = [ 'b', 'd' ]; 'outer: for va in &a { for vb in &b { if va == vb { continue 'outer; } } println!("{}", va); } }
'outer is a label used to refer to the outer loop. Labels in Rust start with a '.
输出
rust
复制代码
a c e
43. Break outer loop
Look for a negative value v in 2D integer matrix m. Print it and stop searching.
在2D整数矩阵m中寻找一个负值v，打印出来，停止搜索。
package main import "fmt" import "os" var m = [][]int{ {1, 2, 3}, {11, 0, 30}, {5, -20, 55}, {0, 0, -60}, } func main() { mainloop: for i, line := range m { fmt.Fprintln(os.Stderr, "Searching in line", i) for _, v := range line { if v < 0 { fmt.Println("Found ", v) break mainloop } } } fmt.Println("Done.") }
mainloop is a label used to refer to the outer loop.
输出
Searching in line 0 Searching in line 1 Searching in line 2 Found -20 Done.
fn main() { let m = vec![ vec![1, 2, 3], vec![11, 0, 30], vec![5, -20, 55], vec![0, 0, -60], ]; 'outer: for v in m { 'inner: for i in v { if i < 0 { println!("Found {}", i); break 'outer; } } } }
Loop label syntax is similar to lifetimes.
输出
Found -20
44. Insert element in list
Insert element x at position i in list s. Further elements must be shifted to the right.
在列表s的位置I插入元素x。其他元素必须向右移动。
package main import "fmt" func main() { s := make([]int, 2) s[0] = 0 s[1] = 2 fmt.Println(s) // insert one at index one s = append(s, 0) copy(s[2:], s[1:]) s[1] = 1 fmt.Println(s) }
输出
[0 2] [0 1 2]
fn main() { let mut vec = vec![1, 2, 3]; vec.insert(1, 4); assert_eq!(vec, [1, 4, 2, 3]); vec.insert(4, 5); assert_eq!(vec, [1, 4, 2, 3, 5]); }
45. Pause execution for 5 seconds
在继续下一个指令之前，在当前线程中休眠5秒钟。
package main import ( "fmt" "time" ) func main() { time.Sleep(5 * time.Second) fmt.Println("Done.") }
use std::{thread, time}; thread::sleep(time::Duration::from_secs(5));
use std::{thread, time};thread::sleep(time::Duration::from_secs(5));
46. Extract beginning of string (prefix)
Create string t consisting of the 5 first characters of string s. Make sure that multibyte characters are properly handled.
创建由字符串s的前5个字符组成的字符串t。 确保正确处理多字节字符。
package main import "fmt" func main() { s := "Привет" t := string([]rune(s)[:5]) fmt.Println(t) }
输出
Приве
fn main() { let s = "été 😁 torride"; let t = s.char_indices().nth(5).map_or(s, |(i, _)| &s[..i]); println!("{}", t); }
输出
été 😁
47. Extract string suffix
Create string t consisting in the 5 last characters of string s. Make sure that multibyte characters are properly handled.
创建由字符串s的最后5个字符组成的字符串t。 确保正确处理多字节字符
package main import "fmt" func main() { s := "hello, world! 문자" t := string([]rune(s)[len([]rune(s))-5:]) fmt.Println(t) }
输出
d! 문자
fn main() { let s = "tükörfúrógép"; let last5ch = s.chars().count() - 5; let s2: String = s.chars().skip(last5ch).collect(); println!("{}", s2); }
输出
rógép
48. Multi-line string literal
Assign to variable s a string literal consisting in several lines of text, including newlines.
给变量s赋值一个由几行文本组成的字符串，包括换行符。
package main import ( "fmt" ) func main() { s := `Huey Dewey Louie` fmt.Println(s) }
输出
Huey Dewey Louie
fn main() { let s = "line 1 line 2 line 3"; print!("{}", &s); }
输出
line 1 line 2 line 3
or
fn main() { let s = r#"Huey Dewey Louie"#; print!("{}", &s); }
输出
Huey Dewey Louie
49. Split a space-separated string
拆分用空格分隔的字符串
Build list chunks consisting in substrings of input string s, separated by one or more space characters.
构建由输入字符串的子字符串组成的列表块，由一个或多个空格字符分隔。
package main import ( "fmt" "strings" ) func main() { s := "Un dos tres" chunks := strings.Split(s, " ") fmt.Println(len(chunks)) fmt.Println(chunks) s = " Un dos tres " chunks = strings.Split(s, " ") fmt.Println(len(chunks)) fmt.Println(chunks) s = "Un dos" chunks = strings.Split(s, " ") fmt.Println(len(chunks)) fmt.Println(chunks) }
输出
3 [Un dos tres] 5 [ Un dos tres ] 3 [Un dos]
or
package main import ( "fmt" "strings" ) func main() { s := "hello world" chunks := strings.Fields(s) fmt.Println(chunks) }
输出为
[hello world]
and
package main import ( "fmt" "strings" ) func main() { s := "Un dos tres" chunks := strings.Fields(s) fmt.Println(len(chunks)) fmt.Println(chunks) s = " Un dos tres " chunks = strings.Fields(s) fmt.Println(len(chunks)) fmt.Println(chunks) s = "Un dos" chunks = strings.Fields(s) fmt.Println(len(chunks)) fmt.Println(chunks) }
输出
3 [Un dos tres] 3 [Un dos tres] 2 [Un dos]
strings.Fields 就只能干这个事儿
fn main() { let s = "What a mess"; let chunks: Vec<_> = s.split_whitespace().collect(); println!("{:?}", chunks); }
输出
["What", "a", "mess"]
or
fn main() { let s = "What a mess"; let chunks: Vec<_> = s.split_ascii_whitespace().collect(); println!("{:?}", chunks); }
书橱
["What", "a", "mess"]
or
fn main() { let s = "What a mess"; let chunks: Vec<_> = s.split(' ').collect(); println!("{:?}", chunks); }
输出
["What", "a", "", "mess"]
50. Make an infinite loop
写一个无限循环
for { // Do something }
package main import "fmt" func main() { k := 0 for { fmt.Println("Hello, playground") k++ if k == 5 { break } } }
输出
Hello, playground Hello, playground Hello, playground Hello, playground Hello, playground
loop { // Do something }
