231. Test if bytes are a valid UTF-8 string
Set b to true if the byte sequence s consists entirely of valid UTF-8 character code points, false otherwise.
测试字节是否是有效的UTF-8字符串
package main import ( "fmt" "unicode/utf8" ) func main() { { s := []byte("Hello, 世界") b := utf8.Valid(s) fmt.Println(b) } { s := []byte{0xff, 0xfe, 0xfd} b := utf8.Valid(s) fmt.Println(b) } }
true false
fn main() { { let bytes = [0xc3, 0x81, 0x72, 0x76, 0xc3, 0xad, 0x7a]; let b = std::str::from_utf8(&bytes).is_ok(); println!("{}", b); } { let bytes = [0xc3, 0x81, 0x81, 0x76, 0xc3, 0xad, 0x7a]; let b = std::str::from_utf8(&bytes).is_ok(); println!("{}", b); } }
true false
234. Encode bytes to base64
Assign to string s the standard base64 encoding of the byte array data, as specified by RFC 4648.
将字节编码为base64
package main import ( "encoding/base64" "fmt" ) func main() { data := []byte("Hello world") s := base64.StdEncoding.EncodeToString(data) fmt.Println(s) }
//use base64; fn main() { let d = "Hello, World!"; let b64txt = base64::encode(d); println!("{}", b64txt); }
235. Decode base64
Assign to byte array data the bytes represented by the base64 string s, as specified by RFC 4648.
解码base64
package main import ( "encoding/base64" "fmt" ) func main() { str := "SGVsbG8gd29ybGQ=" data, err := base64.StdEncoding.DecodeString(str) if err != nil { fmt.Println("error:", err) return } fmt.Printf("%q\n", data) }
//use base64; fn main() { let d = "SGVsbG8sIFdvcmxkIQ=="; let bytes = base64::decode(d).unwrap(); println!("Hex: {:x?}", bytes); println!("Txt: {}", std::str::from_utf8(&bytes).unwrap()); }
Hex: [48, 65, 6c, 6c, 6f, 2c, 20, 57, 6f, 72, 6c, 64, 21] Txt: Hello, World!
237. Xor integers
Assign to c the result of (a xor b)
异或运算
异或整数
package main import ( "fmt" ) func main() { a, b := 230, 42 c := a ^ b fmt.Printf("a is %12b\n", a) fmt.Printf("b is %12b\n", b) fmt.Printf("c is %12b\n", c) fmt.Println("c ==", c) }
a is 11100110 b is 101010 c is 11001100 c == 204
or
package main import ( "fmt" "math/big" ) func main() { a, b := big.NewInt(230), big.NewInt(42) c := new(big.Int) c.Xor(a, b) fmt.Printf("a is %12b\n", a) fmt.Printf("b is %12b\n", b) fmt.Printf("c is %12b\n", c) fmt.Println("c ==", c) }
a is 11100110 b is 101010 c is 11001100 c == 204
fn main() { let a = 230; let b = 42; let c = a ^ b; println!("{}", c); }
238. Xor byte arrays
Write in a new byte array c the xor result of byte arrays a and b.
a and b have the same size.
异或字节数组
package main import ( "fmt" ) func main() { a, b := []byte("Hello"), []byte("world") c := make([]byte, len(a)) for i := range a { c[i] = a[i] ^ b[i] } fmt.Printf("a is %08b\n", a) fmt.Printf("b is %08b\n", b) fmt.Printf("c is %08b\n", c) fmt.Println("c ==", c) fmt.Printf("c as string would be %q\n", string(c)) }
a is [01001000 01100101 01101100 01101100 01101111] b is [01110111 01101111 01110010 01101100 01100100] c is [00111111 00001010 00011110 00000000 00001011] c == [63 10 30 0 11] c as string would be "?\n\x1e\x00\v"
or
package main import ( "fmt" ) type T [5]byte func main() { var a, b T copy(a[:], "Hello") copy(b[:], "world") var c T for i := range a { c[i] = a[i] ^ b[i] } fmt.Printf("a is %08b\n", a) fmt.Printf("b is %08b\n", b) fmt.Printf("c is %08b\n", c) fmt.Println("c ==", c) fmt.Printf("c as string would be %q\n", string(c[:])) }
a is [01001000 01100101 01101100 01101100 01101111] b is [01110111 01101111 01110010 01101100 01100100] c is [00111111 00001010 00011110 00000000 00001011] c == [63 10 30 0 11] c as string would be "?\n\x1e\x00\v"
fn main() { let a: &[u8] = "Hello".as_bytes(); let b: &[u8] = "world".as_bytes(); let c: Vec<_> = a.iter().zip(b).map(|(x, y)| x ^ y).collect(); println!("{:?}", c); }
239. Find first regular expression match
Assign to string x the first word of string s consisting of exactly 3 digits, or the empty string if no such match exists.
A word containing more digits, or 3 digits as a substring fragment, must not match.
查找第一个正则表达式匹配项
package main import ( "fmt" "regexp" ) func main() { re := regexp.MustCompile(`\b\d\d\d\b`) for _, s := range []string{ "", "12", "123", "1234", "I have 12 goats, 3988 otters, 224 shrimps and 456 giraffes", "See p.456, for word boundaries", } { x := re.FindString(s) fmt.Printf("%q -> %q\n", s, x) } }
"" -> "" "12" -> "" "123" -> "123" "1234" -> "" "I have 12 goats, 3988 otters, 224 shrimps and 456 giraffes" -> "224" "See p.456, for word boundaries" -> "456"
use regex::Regex; fn main() { let sentences = vec![ "", "12", "123", "1234", "I have 12 goats, 3988 otters, 224 shrimps and 456 giraffes", "See p.456, for word boundaries", ]; for s in sentences { let re = Regex::new(r"\b\d\d\d\b").expect("failed to compile regex"); let x = re.find(s).map(|x| x.as_str()).unwrap_or(""); println!("[{}] -> [{}]", &s, &x); } }
[] -> [] [12] -> [] [123] -> [123] [1234] -> [] [I have 12 goats, 3988 otters, 224 shrimps and 456 giraffes] -> [224] [See p.456, for word boundaries] -> [456]
240. Sort 2 lists together
Lists a and b have the same length. Apply the same permutation to a and b to have them sorted based on the values of a.
将两个列表排序在一起.列表a和b的长度相同。对a和b应用相同的排列，根据a的值对它们进行排序。
package main import ( "fmt" "sort" ) type K int type T string type sorter struct { k []K t []T } func (s *sorter) Len() int { return len(s.k) } func (s *sorter) Swap(i, j int) { // Swap affects 2 slices at once. s.k[i], s.k[j] = s.k[j], s.k[i] s.t[i], s.t[j] = s.t[j], s.t[i] } func (s *sorter) Less(i, j int) bool { return s.k[i] < s.k[j] } func main() { a := []K{9, 3, 4, 8} b := []T{"nine", "three", "four", "eight"} sort.Sort(&sorter{ k: a, t: b, }) fmt.Println(a) fmt.Println(b) }
[3 4 8 9] [three four eight nine]
fn main() { let a = vec![30, 20, 40, 10]; let b = vec![101, 102, 103, 104]; let mut tmp: Vec<_> = a.iter().zip(b).collect(); tmp.as_mut_slice().sort_by_key(|(&x, _y)| x); let (aa, bb): (Vec<i32>, Vec<i32>) = tmp.into_iter().unzip(); println!("{:?}, {:?}", aa, bb); }
