Sleep
Write a program that does the following in this order:
- Input an amount of time to sleep in whatever units are most natural for your language (milliseconds, seconds, ticks, etc.). This unit should be noted in comments or in a description.
- Print "Sleeping..."
- Sleep the main thread for the given amount of time.
- Print "Awake!"
- End.
You are encouraged to solve this task according to the task description, using any language you may know.
Ada
The Ada delay statement takes an argument of type Duration, which is a real number counting the number of seconds to delay. Thus, 2.0 will delay 2.0 seconds, while 0.001 will delay 0.001 seconds.
<lang ada>with Ada.Text_Io; use Ada.Text_Io; with Ada.Float_Text_Io; use Ada.Float_Text_Io;
procedure Sleep is
In_Val : Float;
begin
Get(In_Val);
Put_Line("Sleeping...");
delay Duration(In_Val);
Put_Line("Awake!");
end Sleep;</lang>
AutoHotkey
<lang AutoHotkey>TrayTip, sleeping, sleeping sleep, 2000 ; 2 seconds TrayTip, awake, awake Msgbox, awake</lang>
BASH
<lang bash>read -p "Enter a time in seconds to sleep: " seconds echo "Sleeping..." sleep $seconds echo "Awake!"</lang>
BASIC
<lang qbasic>INPUT sec 'the SLEEP command takes seconds PRINT "Sleeping..." SLEEP sec PRINT "Awake!"</lang> "SLEEP" with no argument will sleep until a button is pressed on the keyboard (including modifier keys such as shift or control). Also, pressing a key while SLEEP is waiting for a specific amount of time (as above) will end the SLEEP.
C
The function sleep needs seconds, which are read from the standard input.
<lang c>#include <stdio.h>
- include <unistd.h>
int main() {
unsigned int seconds;
scanf("%u", &seconds);
printf("Sleeping...\n");
sleep(seconds);
printf("Awake!\n");
return 0;
}</lang>
C++
<lang cpp>#include <unistd.h>
- include <iostream>
using namespace std;
int main(int argc, char* argv[]) {
useconds_t microseconds; cin >> microseconds; cout << "Sleeping..." << endl; usleep(microseconds); cout << "Awake!" << endl; return 0;
}</lang>
C#
<lang csharp>using System; using System.Threading;
class Program {
static void Main(string[] args)
{
int sleep = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("Sleeping...");
Thread.Sleep(sleep); //milliseconds
Console.WriteLine("Awake!");
}
}</lang>
Common Lisp
<lang lisp>(defun test-sleep ()
(let ((seconds (read))) (format t "Sleeping...~%") (sleep seconds) (format t "Awake!~%")))
(test-sleep)</lang>
D
<lang d> import std.c.time; import std.stdio; import std.string; void main() {
writef("Enter a time(seconds) to sleep: ");
writefln("Sleeping...");
sleep(atoi(readln())*1000);
writefln("Awake!");
} </lang>
E
You can't do that.
No, really. E's approach to timing, concurrency, and IO is non-blocking; if you want to wait for something, you say what you want to do when it happens — i.e. callbacks. There are no threads of control which can be stopped — except automatically when they just have nothing to do.
So, the closest thing possible to the task description is to wait for the specified time to pass, then do whatever the next thing is.
def sleep(milliseconds :int, nextThing) {
stdout.println("Sleeping...")
timer.whenPast(timer.now() + milliseconds, fn {
stdout.println("Awake!")
nextThing()
})
}
Erlang
Erlang doesn't really have such a thing as a main thread. However, sleeping any process can be done with the timer:sleep/1 function: <lang erlang> main() ->
io:format("Sleeping...~n"),
timer:sleep(1000), %% in milliseconds
io:format("Awake!~n").</lang>
It is to be noted that Erlang's sleep function is implemented in Erlang with a timeout on a receive, so you may sometimes encounter the following way of sleeping a process: <lang erlang> main() ->
io:format("Sleeping...~n"),
receive
after 1000 -> ok %% in milliseconds
end,
io:format("Awake!~n").</lang>
which is the way it is implemented in the timer module.
Forth
: sleep ( ms -- ) ." Sleeping..." ms ." awake." cr ;
Haskell
<lang haskell>import Control.Concurrent
main = do seconds <- readLn
putStrLn "Sleeping..."
threadDelay $ round $ seconds * 1000000
putStrLn "Awake!"</lang>
Java
<lang java>import java.util.Scanner;
public class Sleep{ public static void main(String[] args) throws InterruptedException{ Scanner input = new Scanner(System.in); int ms = input.nextInt(); //Java's sleep method accepts milliseconds System.out.println("Sleeping..."); Thread.sleep(ms); System.out.println("Awake!"); } }</lang>
Objective-C
<lang objc>[NSThread sleepForTimeInterval:numSeconds];
// number of seconds can be fractional (it's a double)</lang>
OCaml
<lang ocaml>#load "unix.cma";; let seconds = read_int ();; print_endline "Sleeping...";; Unix.sleep seconds;; (* number is integer in seconds *) print_endline "Awake!";;</lang>
or <lang ocaml>#load "unix.cma";;
- directory "+threads";;
- load "threads.cma";;
let seconds = read_float ();; print_endline "Sleeping...";; Thread.delay seconds;; (* number is in seconds ... but accepts fractions *) print_endline "Awake!";;</lang>
Perl
seconds: <lang perl>$seconds = <>; print "Sleeping...\n"; sleep $seconds; # number is in seconds print "Awake!\n";</lang>
microseconds and nanoseconds using the Time::HiRes module: <lang perl>use Time::HiRes qw( usleep nanosleep );
$microseconds = <>; print "Sleeping...\n"; usleep $microseconds; print "Awake!\n";
$nanoseconds = <>; print "Sleeping...\n"; nanosleep $nanoseconds; print "Awake!\n";</lang>
PHP
seconds: <lang php>$seconds = 42; echo "Sleeping...\n"; sleep($seconds); # number is integer in seconds echo "Awake!\n";</lang>
microseconds: <lang php>$microseconds = 42000000; echo "Sleeping...\n"; usleep($microseconds); # number is integer in microseconds echo "Awake!\n";</lang>
nanoseconds: <lang php>$nanoseconds = 42000000000; echo "Sleeping...\n"; time_nanosleep($seconds, $nanoseconds); # first arg in seconds plus second arg in nanoseconds echo "Awake!\n";</lang>
PowerShell
<lang powershell>$d = [int] (Read-Host Duration in seconds)
Write-Host Sleeping ...
Start-Sleep $d
Write-Host Awake!</lang>
The -Milliseconds parameter to Start-Sleep can be used to allow for sub-second precision in sleeping.
Python
<lang python>import time
seconds = float(raw_input()) print "Sleeping..." time.sleep(seconds) # number is in seconds ... but accepts fractions
- Minimum resolution is system dependent.
print "Awake!"</lang>
R
The call to flush.console is only needed if buffering is turned on. See FAQ for R on windows. The time is given in seconds (fractions allowed, resolution is system dependent). <lang R> sleep <- function(time=1) {
message("Sleeping...")
flush.console()
Sys.sleep(time)
message("Awake!")
}
sleep() </lang>
Ruby
<lang ruby>seconds = gets.to_f puts "Sleeping..." sleep(seconds) # number is in seconds ... but accepts fractions
- Minimum resolution is system dependent.
puts "Awake!"</lang>
Standard ML
<lang ocaml>(TextIO.print "input a number of seconds please: "; let val seconds = valOf (Int.fromString (valOf (TextIO.inputLine TextIO.stdIn))) in
TextIO.print "Sleeping...\n";
OS.Process.sleep (Time.fromReal seconds); (* it takes a Time.time data structure as arg,
but in my implementation it seems to round down to the nearest second.
I dunno why; it doesn't say anything about this in the documentation *)
TextIO.print "Awake!\n"
end)</lang>
Tcl
<lang tcl>puts -nonewline "Enter a number of milliseconds to sleep: " flush stdout set millis [gets stdin] puts Sleeping... after $millis puts Awake!</lang>
TI-89 BASIC
Local dur_secs,st0,st,seconds Define seconds() = Func Local hms getTime()→hms Return ((hms[1] * 60 + hms[2]) * 60) + hms[3] EndFunc ClockOn Prompt dur_secs Disp "Sleeping..." seconds()→st st→st0 While when(st<st0, st+86400, st) - st0 < dur_secs seconds()→st EndWhile Disp "Awake!"
Toka
This makes use of the sleep() function from libc which suspends execution for a specified number of seconds.
1 import sleep as sleep() [ ." Sleeping...\n" sleep() drop ." Awake!\n" bye ] is sleep 45 sleep
Vedit macro language
<lang vedit>#1 = Get_Num("Sleep time in 1/10 seconds: ") Message("Sleeping...\n") Sleep(#1) Message("Awake!\n")</lang>