View Problem
Parallel
Threads

Create a multithreaded "Hello World"

Create a program which outputs the string "Hello World" to the console, multiple times, using separate threads or processes.

Example:

-Output-

Thread one says Hello World!
Thread two says Hello World!
Thread four says Hello World!
Thread three says Hello World!

-Notice that the threads can print in any order.
DiskEdit
ruby
%w[one two three four].each do |number|
Thread.new(number) { |number|
puts "Thread #{number} says Hello World!"
}.join
end
DiskEdit
clojure
(doseq [msg ["one" "two" "three" "four"]]
(future (println "Thread" msg "says Hello World!")))
DiskEdit
clojure
(dorun (pmap #(println (str "Thread " % " says Hello World!")) '("one" "two" "three" "four")))
ExpandDiskEdit
clojure
(dorun (map (fn [n] (.start (Thread. #(println (str "Thread " n " says Hello World!")))))
'("one" "two" "three" "four")))
DiskEdit
fsharp
let mappedString =
["Thread one says Hello World!";
"Thread two says Hello World!";
"Thread four says Hello World!";
"Thread three says Hello World!"]
|> Seq.map (fun str -> async { printfn "%s" str })

Async.RunSynchronously (Async.Parallel mappedString)
DiskEdit
cpp
#include <iostream>
#include <string>

using namespace std;

int main(){
int pid;
string text[4]={"one","two","three","four"};
for (int i=0;i<4;i++){
pid=fork();
if (pid>0){
//cout << "Process("<<pid<<") - " << "Thread " << text[i] << " says Hello World!" << endl;
cout << "Thread " << text[i] << " says Hello World!" << endl;
exit(0);
}
}
return 0;
}
DiskEdit
cpp
#include <iostream>
#include <string>

#include <omp.h>

int main() {
unsigned int const num_threads = 4;

std::string const names[] = { "one", "two", "three", "four" };

# pragma omp parallel num_threads(num_threads)
{
unsigned const id = omp_get_thread_num();
// Stream concatenation isn't thread-safe so we use a critical section.
# pragma omp critical
std::cout << "Thread " << names[id] << " says Hello World!" << std::endl;
}
}

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