171. Add an element at the end of a list
Append element x to the list s.
在list尾部添加元素
package main import "fmt" func main() { s := []int{1, 1, 2, 3, 5, 8, 13} x := 21 s = append(s, x) fmt.Println(s) }
fn main() { let mut s = vec![1, 2, 3]; let x = 99; s.push(x); println!("{:?}", s); }
172. Insert entry in map
Insert value v for key k in map m.
向map中写入元素
package main import "fmt" func main() { m := map[string]int{"one": 1, "two": 2} k := "three" v := 3 m[k] = v fmt.Println(m) }
use std::collections::HashMap; fn main() { let mut m: HashMap<&str, i32> = [("one", 1), ("two", 2)].iter().cloned().collect(); let (k, v) = ("three", 3); m.insert(k, v); println!("{:?}", m); }
173. Format a number with grouped thousands
Number will be formatted with a comma separator between every group of thousands.
按千位格式化数字
package main import ( "fmt" "golang.org/x/text/language" "golang.org/x/text/message" ) // The Playground doesn't work with import of external packages. // However, you may copy this source and test it on your workstation. func main() { p := message.NewPrinter(language.English) s := p.Sprintf("%d\n", 1000) fmt.Println(s) // Output: // 1,000 }
or
package main import ( "fmt" "github.com/floscodes/golang-thousands" "strconv" ) // The Playground takes more time when importing external packages. // However, you may want to copy this source and test it on your workstation. func main() { n := strconv.Itoa(23489) s := thousands.Separate(n, "en") fmt.Println(s) // Output: // 23,489 }
use separator::Separatable; println!("{}", 1000.separated_string());
174. Make HTTP POST request
Make a HTTP request with method POST to URL u
发起http POST请求
package main import ( "fmt" "io" "io/ioutil" "net" "net/http" ) func main() { contentType := "text/plain" var body io.Reader u := "http://" + localhost + "/hello" response, err := http.Post(u, contentType, body) check(err) buffer, err := ioutil.ReadAll(response.Body) check(err) fmt.Println("POST response:", response.StatusCode, string(buffer)) response, err = http.Get(u) check(err) buffer, err = ioutil.ReadAll(response.Body) check(err) fmt.Println("GET response:", response.StatusCode, string(buffer)) } const localhost = "127.0.0.1:3000" func init() { http.HandleFunc("/hello", myHandler) startServer() } func myHandler(w http.ResponseWriter, r *http.Request) { if r.Method != "POST" { w.WriteHeader(http.StatusBadRequest) fmt.Fprintf(w, "Refusing request verb %q", r.Method) return } fmt.Fprintf(w, "Hello POST :)") } func startServer() { listener, err := net.Listen("tcp", localhost) check(err) go http.Serve(listener, nil) } func check(err error) { if err != nil { panic(err) } }
POST response: 200 Hello Alice (POST) GET response: 400 Refusing request verb "GET"
or
package main import ( "fmt" "io/ioutil" "net" "net/http" "net/url" ) func main() { formValues := url.Values{ "who": []string{"Alice"}, } u := "http://" + localhost + "/hello" response, err := http.PostForm(u, formValues) check(err) buffer, err := ioutil.ReadAll(response.Body) check(err) fmt.Println("POST response:", response.StatusCode, string(buffer)) response, err = http.Get(u) check(err) buffer, err = ioutil.ReadAll(response.Body) check(err) fmt.Println("GET response:", response.StatusCode, string(buffer)) } const localhost = "127.0.0.1:3000" func init() { http.HandleFunc("/hello", myHandler) startServer() } func myHandler(w http.ResponseWriter, r *http.Request) { if r.Method != "POST" { w.WriteHeader(http.StatusBadRequest) fmt.Fprintf(w, "Refusing request verb %q", r.Method) return } fmt.Fprintf(w, "Hello %s (POST)", r.FormValue("who")) } func startServer() { listener, err := net.Listen("tcp", localhost) check(err) go http.Serve(listener, nil) } func check(err error) { if err != nil { panic(err) } }
[dependencies] error-chain = "0.12.4" reqwest = { version = "0.11.2", features = ["blocking"] } use error_chain::error_chain; use std::io::Read; let client = reqwest::blocking::Client::new(); let mut response = client.post(u).body("abc").send()?;
175. Bytes to hex string
From array a of n bytes, build the equivalent hex string s of 2n digits. Each byte (256 possible values) is encoded as two hexadecimal characters (16 possible values per digit).
字节转十六进制字符串
package main import ( "encoding/hex" "fmt" ) func main() { a := []byte("Hello") s := hex.EncodeToString(a) fmt.Println(s) }
use core::fmt::Write; fn main() -> core::fmt::Result { let a = vec![22, 4, 127, 193]; let n = a.len(); let mut s = String::with_capacity(2 * n); for byte in a { write!(s, "{:02X}", byte)?; } dbg!(s); Ok(()) }
176. Hex string to byte array
From hex string s of 2n digits, build the equivalent array a of n bytes. Each pair of hexadecimal characters (16 possible values per digit) is decoded into one byte (256 possible values).
十六进制字符串转字节数组
package main import ( "encoding/hex" "fmt" "log" ) func main() { s := "48656c6c6f" a, err := hex.DecodeString(s) if err != nil { log.Fatal(err) } fmt.Println(a) fmt.Println(string(a)) }
[72 101 108 108 111] Hello
use hex::FromHex let a: Vec<u8> = Vec::from_hex(s).expect("Invalid Hex String");
178. Check if point is inside rectangle
Set boolean b to true if if the point with coordinates (x,y) is inside the rectangle with coordinates (x1,y1,x2,y2) , or to false otherwise. Describe if the edges are considered to be inside the rectangle.
检查点是否在矩形内
package main import ( "fmt" "image" ) func main() { x1, y1, x2, y2 := 1, 1, 50, 100 r := image.Rect(x1, y1, x2, y2) x, y := 10, 10 p := image.Pt(x, y) b := p.In(r) fmt.Println(b) x, y = 100, 100 p = image.Pt(x, y) b = p.In(r) fmt.Println(b) }
true false
struct Rect { x1: i32, x2: i32, y1: i32, y2: i32, } impl Rect { fn contains(&self, x: i32, y: i32) -> bool { return self.x1 < x && x < self.x2 && self.y1 < y && y < self.y2; } }
179. Get center of a rectangle
Return the center c of the rectangle with coördinates(x1,y1,x2,y2)
获取矩形的中心
import "image" c := image.Pt((x1+x2)/2, (y1+y2)/2)
struct Rectangle { x1: f64, y1: f64, x2: f64, y2: f64, } impl Rectangle { pub fn center(&self) -> (f64, f64) { ((self.x1 + self.x2) / 2.0, (self.y1 + self.y2) / 2.0) } } fn main() { let r = Rectangle { x1: 5., y1: 5., x2: 10., y2: 10., }; println!("{:?}", r.center()); }
180. List files in directory
Create list x containing the contents of directory d.
x may contain files and subfolders.
No recursive subfolder listing.
列出目录中的文件
package main import ( "fmt" "io/ioutil" "log" ) func main() { d := "/" x, err := ioutil.ReadDir(d) if err != nil { log.Fatal(err) } for _, f := range x { fmt.Println(f.Name()) } }
.dockerenv bin dev etc home lib lib64 proc root sys tmp tmpfs usr var
use std::fs; fn main() { let d = "/etc"; let x = fs::read_dir(d).unwrap(); for entry in x { let entry = entry.unwrap(); println!("{:?}", entry.path()); } }
or
fn main() { let d = "/etc"; let x = std::fs::read_dir(d) .unwrap() .collect::<Result<Vec<_>, _>>() .unwrap(); for entry in x { println!("{:?}", entry.path()); } }
"/etc/issue.net" "/etc/bindresvport.blacklist" "/etc/rc1.d" "/etc/hostname" "/etc/xattr.conf" "/etc/resolv.conf" "/etc/pam.conf" "/etc/mke2fs.conf" "/etc/e2scrub.conf" "/etc/update-motd.d" "/etc/terminfo" "/etc/alternatives" "/etc/ld.so.cache" "/etc/networks" "/etc/profile" "/etc/debconf.conf" "/etc/security" "/etc/.pwd.lock" "/etc/gai.conf" "/etc/dpkg" "/etc/rc3.d" "/etc/fstab" "/etc/gshadow" "/etc/sysctl.conf" "/etc/rc2.d" "/etc/selinux" "/etc/ld.so.conf.d" "/etc/os-release" "/etc/libaudit.conf" "/etc/login.defs" "/etc/skel" "/etc/shells" "/etc/rc4.d" "/etc/cron.d" "/etc/default" "/etc/lsb-release" "/etc/apt" "/etc/debian_version" "/etc/machine-id" "/etc/deluser.conf" "/etc/group" "/etc/legal" "/etc/rc6.d" "/etc/init.d" "/etc/sysctl.d" "/etc/pam.d" "/etc/passwd" "/etc/rc5.d" "/etc/bash.bashrc" "/etc/hosts" "/etc/rc0.d" "/etc/environment" "/etc/cron.daily" "/etc/shadow" "/etc/ld.so.conf" "/etc/subgid" "/etc/opt" "/etc/logrotate.d" "/etc/subuid" "/etc/profile.d" "/etc/adduser.conf" "/etc/issue" "/etc/rmt" "/etc/host.conf" "/etc/rcS.d" "/etc/nsswitch.conf" "/etc/systemd" "/etc/kernel" "/etc/mtab" "/etc/shadow-" "/etc/passwd-" "/etc/subuid-" "/etc/gshadow-" "/etc/subgid-" "/etc/group-" "/etc/ethertypes" "/etc/logcheck" "/etc/gss" "/etc/bash_completion.d" "/etc/X11" "/etc/perl" "/etc/ca-certificates" "/etc/protocols" "/etc/ca-certificates.conf" "/etc/python2.7" "/etc/localtime" "/etc/xdg" "/etc/timezone" "/etc/mailcap.order" "/etc/emacs" "/etc/ssh" "/etc/magic.mime" "/etc/services" "/etc/ssl" "/etc/ldap" "/etc/rpc" "/etc/mime.types" "/etc/magic" "/etc/mailcap" "/etc/inputrc"
