182. Quine program
Output the source of the program.
输出程序的源代码
package main import "fmt" func main() { fmt.Printf("%s%c%s%c\n", s, 0x60, s, 0x60) } var s = `package main import "fmt" func main() { fmt.Printf("%s%c%s%c\n", s, 0x60, s, 0x60) } var s = `
输出：
package main import "fmt" func main() { fmt.Printf("%s%c%s%c\n", s, 0x60, s, 0x60) } var s = `package main import "fmt" func main() { fmt.Printf("%s%c%s%c\n", s, 0x60, s, 0x60) } var s = `
fn main() { let x = "fn main() {\n let x = "; let y = "print!(\"{}{:?};\n let y = {:?};\n {}\", x, x, y, y)\n}\n"; print!("{}{:?}; let y = {:?}; {}", x, x, y, y) }
输出：
fn main() { let x = "fn main() {\n let x = "; let y = "print!(\"{}{:?};\n let y = {:?};\n {}\", x, x, y, y)\n}\n"; print!("{}{:?}; let y = {:?}; {}", x, x, y, y) }
or
fn main(){print!("{},{0:?})}}","fn main(){print!(\"{},{0:?})}}\"")}
输出：
fn main(){print!("{},{0:?})}}","fn main(){print!(\"{},{0:?})}}\"")}
184. Tomorrow
Assign to variable t a string representing the day, month and year of the day after the current date.
明天的日期
import "time" t := time.Now().Add(24 * time.Hour).Format("2006-01-02")
fn main() { let t = chrono::Utc::now().date().succ().to_string(); println!("{}", t); }
185. Execute function in 30 seconds
Schedule the execution of f(42) in 30 seconds.
30秒内执行功能
import "time" timer := time.AfterFunc( 30*time.Second, func() { f(42) })
or
package main import ( "fmt" "time" ) func main() { fmt.Println("Scheduling f(42)") go func() { time.Sleep(3 * time.Second) f(42) }() // Poor man's waiting of completion of f. // Don't do this in prod, use proper synchronization instead. time.Sleep(4 * time.Second) } func f(i int) { fmt.Println("Received", i) }
use std::time::Duration; use std::thread::sleep; sleep(Duration::new(30, 0)); f(42);
186. Exit program cleanly
Exit a program cleanly indicating no error to OS
干净地退出程序
package main import ( "fmt" "os" ) func main() { fmt.Println("A") os.Exit(0) fmt.Println("B") }
or
package main import ( "fmt" "os" ) func main() { process1() process2() process3() } func process1() { fmt.Println("process 1") } func process2() { fmt.Println("process 2") defer fmt.Println("A") defer os.Exit(0) defer fmt.Println("B") fmt.Println("C") } func process3() { fmt.Println("process 3") }
process 1 process 2 C B
use std::process::exit; fn main() { println!("A"); exit(0); println!("B"); }
189. Filter and transform list
Produce a new list y containing the result of function T applied to all elements e of list x that match the predicate P.
过滤和转换列表
package main import ( "fmt" ) func P(e int) bool { // Predicate "is even" return e%2 == 0 } type Result = int func T(e int) Result { // Transformation "square" return e * e } func main() { x := []int{4, 5, 6, 7, 8, 9, 10} var y []Result for _, e := range x { if P(e) { y = append(y, T(e)) } } fmt.Println(y) }
let y = x.iter() .filter(P) .map(T) .collect::<Vec<_>>();
190. Call an external C function
Declare an external C function with the prototype
void foo(double *a, int n);
and call it, passing an array (or a list) of size 10 to a and 10 to n.
Use only standard features of your language.
调用外部C函数
// void foo(double *a, int n); // double a[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; import "C" C.foo(C.a, 10)
extern "C" { /// # Safety /// /// `a` must point to an array of at least size 10 fn foo(a: *mut libc::c_double, n: libc::c_int); } let mut a = [0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0]; let n = 10; unsafe { foo(a.as_mut_ptr(), n); }
191. Check if any value in a list is larger than a limit
Given a one-dimensional array a, check if any value is larger than x, and execute the procedure f if that is the case
检查列表中是否有任何值大于限制
package main import ( "fmt" ) func f() { fmt.Println("Larger found") } func main() { a := []int{1, 2, 3, 4, 5} x := 4 for _, v := range a { if v > x { f() break } } }
fn main() { let a = [5, 6, 8, -20, 9, 42]; let x = 35; if a.iter().any(|&elem| elem > x) { f() } let x = 50; if a.iter().any(|&elem| elem > x) { g() } } fn f() { println!("F") } fn g() { println!("G") }
192. Declare a real variable with at least 20 digits
Declare a real variable a with at least 20 digits; if the type does not exist, issue an error at compile time.
声明一个至少有20位数字的实变量
package main import ( "fmt" "math/big" ) func main() { a, _, err := big.ParseFloat("123456789.123456789123465789", 10, 200, big.ToZero) if err != nil { panic(err) } fmt.Println(a) }
use rust_decimal::Decimal; use std::str::FromStr; let a = Decimal::from_str("1234567890.123456789012345").unwrap();
197. Get a list of lines from a file
Retrieve the contents of file at path into a list of strings lines, in which each element is a line of the file.
从文件中获取行列表.将文件路径中的内容检索到字符串行列表中，其中每个元素都是文件的一行。
package main import ( "fmt" "io/ioutil" "log" "strings" ) func readLines(path string) ([]string, error) { b, err := ioutil.ReadFile(path) if err != nil { return nil, err } lines := strings.Split(string(b), "\n") return lines, nil } func main() { lines, err := readLines("/tmp/file1") if err != nil { log.Fatalln(err) } for i, line := range lines { fmt.Printf("line %d: %s\n", i, line) } } func init() { data := []byte(`foo bar baz`) err := ioutil.WriteFile("/tmp/file1", data, 0644) if err != nil { log.Fatalln(err) } }
line 0: foo line 1: bar line 2: baz
use std::fs::File; use std::io::prelude::*; use std::io::BufReader; fn main() { let path = "/etc/hosts"; let lines = BufReader::new(File::open(path).unwrap()) .lines() .collect::<Vec<_>>(); println!("{:?}", lines); }
198. Abort program execution with error condition
Abort program execution with error condition x (where x is an integer value)
出现错误情况时中止程序执行
package main import ( "os" ) func main() { x := 1 os.Exit(x) }
Program exited: status 1.
use std::process; process::exit(x);
200. Return hypotenuse
Returns the hypotenuse h of the triangle where the sides adjacent to the square angle have lengths x and y.
返回三角形的斜边h，其中与直角相邻的边的长度为x和y。
package main import ( "fmt" "math" ) func main() { x := 1.0 y := 1.0 h := math.Hypot(x, y) fmt.Println(h) }
fn main() { let (x, y) = (1.0, 1.0); let h = hypot(x, y); println!("{}", h); } fn hypot(x: f64, y: f64) -> f64 { let num = x.powi(2) + y.powi(2); num.powf(0.5) }
