Rust vs Go:常用語(yǔ)法對(duì)比(三)

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題圖來(lái)自When to use Rust and when to use Go^[1]

41. Reverse a string

反轉(zhuǎn)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)
}

輸出

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>();

fn?main()?{
????let?s?=?"lorém?ipsüm?dol?r?sit?amor???";
????let?t:?String?=?s.chars().rev().collect();
????println!("{}",?t);
}

輸出

? roma tis r?lod 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中的每個(gè)項(xiàng)目v。為此，編寫(xiě)一個(gè)外部循環(huán)來(lái)迭代a，編寫(xiě)一個(gè)內(nèi)部循環(huán)來(lái)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.

輸出

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 '.

輸出

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整數(shù)矩陣m中尋找一個(gè)負(fù)值v，打印出來(lái)，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.

輸出

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.

輸出

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。其他元素必須向右移動(dòng)。

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)
}

輸出

[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

在繼續(xù)下一個(gè)指令之前，在當(dāng)前線程中休眠5秒鐘。

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));

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.

創(chuàng)建由字符串s的前5個(gè)字符組成的字符串t。確保正確處理多字節(jié)字符。

package?main

import?"fmt"

func?main()?{
?s?:=?"Привет"
?t?:=?string([]rune(s)[:5])
?
?fmt.Println(t)
}

輸出

Приве

fn?main()?{
????let?s?=?"été????torride";
????
????let?t?=?s.char_indices().nth(5).map_or(s,?|(i,?_)|?&s[..i]);

????println!("{}",?t);
}

輸出

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.

創(chuàng)建由字符串s的最后5個(gè)字符組成的字符串t。確保正確處理多字節(jié)字符

package?main

import?"fmt"

func?main()?{
?s?:=?"hello,?world!???"
?t?:=?string([]rune(s)[len([]rune(s))-5:])
?fmt.Println(t)
}

輸出

d! ??

fn?main()?{
????let?s?=?"tük?rfúrógép";
????let?last5ch?=?s.chars().count()?-?5;
????let?s2:?String?=?s.chars().skip(last5ch).collect();
????println!("{}",?s2);
}

輸出

rógép

48. Multi-line string literal

Assign to variable s a string literal consisting in several lines of text, including newlines.

給變量s賦值一個(gè)由幾行文本組成的字符串，包括換行符。

package?main

import?(
?"fmt"
)

func?main()?{
?s?:=?`Huey
Dewey
Louie`

?fmt.Println(s)
}

輸出

Huey
Dewey
Louie

fn?main()?{
????let?s?=?"line?1
line?2
line?3";
????
????print!("{}",?&s);
}

輸出

line?1
line?2
line?3

fn?main()?{
????let?s?=?r#"Huey
Dewey
Louie"#;
????
????print!("{}",?&s);
}

輸出

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.

構(gòu)建由輸入字符串的子字符串組成的列表塊，由一個(gè)或多個(gè)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)
}

輸出

3
[Un?dos?tres]
5
[?Un?dos?tres?]
3
[Un??dos]

package?main

import?(
?"fmt"
?"strings"
)

func?main()?{
?s?:=?"hello?world"
?chunks?:=?strings.Fields(s)

?fmt.Println(chunks)
}

輸出為

[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)
}

輸出

3
[Un?dos?tres]
3
[Un?dos?tres]
2
[Un?dos]

strings.Fields 就只能干這個(gè)事兒

fn?main()?{
????let?s?=?"What?a??mess";

????let?chunks:?Vec<_>?=?s.split_whitespace().collect();

????println!("{:?}",?chunks);
}

輸出

["What",?"a",?"mess"]

fn?main()?{
????let?s?=?"What?a??mess";

????let?chunks:?Vec<_>?=?s.split_ascii_whitespace().collect();

????println!("{:?}",?chunks);
}

輸出

["What",?"a",?"mess"]

fn?main()?{
????let?s?=?"What?a??mess";

????let?chunks:?Vec<_>?=?s.split('?').collect();

????println!("{:?}",?chunks);
}

輸出

["What",?"a",?"",?"mess"]

50. Make an infinite loop

寫(xiě)一個(gè)無(wú)限循環(huán)

for?{
?//?Do?something
}

package?main

import?"fmt"

func?main()?{
?k?:=?0
?for?{
??fmt.Println("Hello,?playground")
??k++
??if?k?==?5?{
???break
??}
?}
}

輸出

Hello,?playground
Hello,?playground
Hello,?playground
Hello,?playground
Hello,?playground

loop?{
?//?Do?something
}

51. Check if map contains key

Determine whether map m contains an entry for key k

檢查map是否有某個(gè)key

package?main

import?(
?"fmt"
)

func?main()?{
?m?:=?map[string]int{
??"uno":??1,
??"dos":??2,
??"tres":?3,
?}

?k?:=?"cinco"
?_,?ok?:=?m[k]
?fmt.Printf("m?contains?key?%q:?%v\n",?k,?ok)

?k?=?"tres"
?_,?ok?=?m[k]
?fmt.Printf("m?contains?key?%q:?%v\n",?k,?ok)
}

輸出

m?contains?key?"cinco":?false
m?contains?key?"tres":?true

use?std::collections::HashMap;

fn?main()?{
????let?mut?m?=?HashMap::new();
????m.insert(1,?"a");
????m.insert(2,?"b");

????let?k?=?2;

????let?hit?=?m.contains_key(&k);

????println!("{:?}",?hit);
}

52. Check if map contains value

檢查map中是否有某個(gè)值

package?main

import?(
?"fmt"
)

func?containsValue(m?map[K]T,?v?T)?bool?{
?for?_,?x?:=?range?m?{
??if?x?==?v?{
???return?true
??}
?}
?return?false
}

//?Arbitrary?types?for?K,?T.
type?K?string
type?T?int

func?main()?{
?m?:=?map[K]T{
??"uno":??1,
??"dos":??2,
??"tres":?3,
?}

?var?v?T?=?5
?ok?:=?containsValue(m,?v)
?fmt.Printf("m?contains?value?%d:?%v\n",?v,?ok)

?v?=?3
?ok?=?containsValue(m,?v)
?fmt.Printf("m?contains?value?%d:?%v\n",?v,?ok)
}

輸出

m?contains?value?5:?false
m?contains?value?3:?true

use?std::collections::BTreeMap;

fn?main()?{
????let?mut?m?=?BTreeMap::new();
????m.insert(11,?"one");
????m.insert(22,?"twenty-two");

????{
????????let?v?=?"eight";
????????let?does_contain?=?m.values().any(|&val|?*val?==?*v);
????????println!("{:?}",?does_contain);
????}

????{
????????let?v?=?"twenty-two";
????????let?does_contain?=?m.values().any(|&val|?*val?==?*v);
????????println!("{:?}",?does_contain);
????}
}

53. Join a list of strings

字符串連接

package?main

import?(
?"fmt"
?"strings"
)

func?main()?{

?x?:=?[]string{"xxx",?"bbb",?"aaa"}
?y?:=?strings.Join(x,?"&")

?fmt.Println(y)

}

輸出

xxx&bbb&aaa

關(guān)于 strings.Joins^[2]

fn?main()?{
????let?x?=?vec!["Lorem",?"ipsum",?"dolor",?"sit",?"amet"];
????let?y?=?x.join(",?");
????println!("{}",?y);
}

輸出

Lorem,?ipsum,?dolor,?sit,?amet

54. Compute sum of integers

計(jì)算整數(shù)之和

package?main

import?"fmt"

func?main()?{
?x?:=?[]int{1,?2,?3}
?s?:=?0
?for?_,?v?:=?range?x?{
??s?+=?v
?}
?fmt.Println(s)
}

輸出

6

fn?main()?{
????let?x:?Vec<usize>?=?(0..=10_000).collect();
????
????eprintln!("Sum?of?0-10,000?=?{}",?x.iter().sum::<usize>())
}

輸出

Sum of 0-10,000 = 50005000

55. Convert integer to string

將整數(shù)轉(zhuǎn)換為字符串

package?main

import?(
?"fmt"
?"strconv"
)

func?main()?{
?var?i?int?=?1234
?s?:=?strconv.Itoa(i)
?fmt.Println(s)
}

輸出

1234

package?main

import?(
?"fmt"
?"strconv"
)

func?main()?{
?var?i?int64?=?1234
?s?:=?strconv.FormatInt(i,?10)
?fmt.Println(s)
}

輸出

1234

package?main

import?"fmt"
import?"math/big"

func?main()?{
?var?i?int?=?1234
?s?:=?fmt.Sprintf("%d",?i)
?fmt.Println(s)

?var?j?int?=?5678
?s?=?fmt.Sprintf("%d",?j)
?fmt.Println(s)

?var?k?*big.Int?=?big.NewInt(90123456)
?s?=?fmt.Sprintf("%d",?k)
?fmt.Println(s)
}

輸出

1234
5678
90123456

fn?main()?{
????let?i?=?123;
????let?s?=?i.to_string();

????println!("{}",?s);
}

輸出

123

fn?main()?{
????let?i?=?123;
????let?s?=?format!("{}",?i);

????println!("{}",?s);
}

輸出

123

56. Launch 1000 parallel tasks and wait for completion

Fork-join : launch the concurrent execution of procedure f with parameter i from 1 to 1000. Tasks are independent and f(i) doesn't return any value. Tasks need not run all at the same time, so you may use a pool. Wait for the completion of the 1000 tasks and then print "Finished".

創(chuàng)建1000個(gè)并行任務(wù)，并等待其完成

package?main

import?(
?"fmt"
?"math/rand"
?"sync"
?"time"
)

func?f(i?int)?{
?d?:=?rand.Int()?%?10000
?time.Sleep(time.Duration(d))
?fmt.Printf("Hello?%v\n",?i)
}

func?main()?{
?var?wg?sync.WaitGroup
?wg.Add(1000)
?for?i?:=?1;?i?<=?1000;?i++?{
??go?func(i?int)?{
???f(i)
???wg.Done()
??}(i)
?}
?wg.Wait()
?fmt.Println("Finished")
}

輸出

Hello?741
Hello?651
Hello?49
...（共計(jì)1000個(gè)）
Hello?xxx

use?std::thread;

fn?f(i:?i32)?{
????i?+?1;
}

fn?main()?{
????let?threads:?Vec<_>?=?(0..10).map(|i|?thread::spawn(move?||?f(i))).collect();

????for?t?in?threads?{
?????t.join();
????}
}

57. Filter list

Create list y containing items from list x satisfying predicate p. Respect original ordering. Don't modify x in-place.

過(guò)濾list中的值

package?main

import?"fmt"

type?T?int

func?main()?{
?x?:=?[]T{1,?2,?3,?4,?5,?6,?7,?8,?9,?10}
?p?:=?func(t?T)?bool?{?return?t%2?==?0?}

?y?:=?make([]T,?0,?len(x))
?for?_,?v?:=?range?x?{
??if?p(v)?{
???y?=?append(y,?v)
??}
?}

?fmt.Println(y)
}

package?main

import?"fmt"

type?T?int

func?main()?{
?x?:=?[]T{1,?2,?3,?4,?5,?6,?7,?8,?9,?10}
?p?:=?func(t?T)?bool?{?return?t%2?==?0?}

?n?:=?0
?for?_,?v?:=?range?x?{
??if?p(v)?{
???n++
??}
?}
?y?:=?make([]T,?0,?n)
?for?_,?v?:=?range?x?{
??if?p(v)?{
???y?=?append(y,?v)
??}
?}

?fmt.Println(y)
}

輸出

[2?4?6?8?10]

fn?main()?{
????let?x?=?vec![1,?2,?3,?4,?5,?6];

????let?y:?Vec<_>?=?x.iter()
????????.filter(|&x|?x?%?2?==?0)
????????.collect();

????println!("{:?}",?y);
}

輸出

[2,?4,?6]

58. Extract file content to a string

提取字符串的文件內(nèi)容

package?main

import?"fmt"
import?"io/ioutil"

func?main()?{
?f?:=?"data.txt"
?b,?err?:=?ioutil.ReadFile(f)
?if?err?!=?nil?{
??panic(err)
?}
?lines?:=?string(b)

?fmt.Println(lines)
}

//?Create?file?in?fake?FS?of?the?Playground.?init?is?executed?before?main.
func?init()?{
?err?:=?ioutil.WriteFile("data.txt",?[]byte(`Un
Dos
Tres`),?0644)
?if?err?!=?nil?{
??panic(err)
?}
}

輸出

Un
Dos
Tres

use?std::fs::File;
use?std::io::prelude::*;

fn?main()?->?Result<(),?()>?{
????let?f?=?"Cargo.toml";

????let?mut?file?=?File::open(f).expect("Can't?open?file.");
????let?mut?lines?=?String::new();
????file.read_to_string(&mut?lines)
????????.expect("Can't?read?file?contents.");

????println!("{}",?lines);

????Ok(())
}

use?std::fs;

fn?main()?{
????let?f?=?"Cargo.toml";

????let?lines?=?fs::read_to_string(f).expect("Can't?read?file.");

????println!("{}",?lines);
}

59. Write to standard error stream

Print the message "x is negative" to standard error (stderr), with integer x value substitution (e.g. "-2 is negative").

寫(xiě)入標(biāo)準(zhǔn)錯(cuò)誤流

package?main

import?(
?"fmt"
?"os"
)

func?main()?{
?x?:=?-2
?fmt.Fprintln(os.Stderr,?x,?"is?negative")
}

輸出

-2?is?negative

fn?main()?{
????let?x?=?-3;
????eprintln!("{}?is?negative",?x);
}

輸出

-3?is?negative

60. Read command line argument

讀取命令行參數(shù)

import?"os"
x?:=?os.Args[1]

use?std::env;

fn?main()?{
????let?first_arg?=?env::args().skip(1).next();

????let?fallback?=?"".to_owned();
????let?x?=?first_arg.unwrap_or(fallback);
????
????println!("{:?}",?x);
}