[C/C++] thread

#include <iostream>
#include <thread>

void foo()
{
    std::cout << "foo thread thread id: " << std::this_thread::get_id() << '\n';
}

void bar(int x)
{
    std::cout << "bar thread thread id: " << std::this_thread::get_id() << '\n';
}

int main()
{
    std::thread first(foo);
    std::thread second(bar, 0);

    std::cout << "main thread id: " << std::this_thread::get_id() << '\n';

    first.join();
    second.join();

    std::cout << "main end\n";

    return 0;
}

#include <iostream>
#include <thread>
#include <chrono>

std::thread::id main_thread_id = std::this_thread::get_id();

void is_main_thread()
{
    if (main_thread_id == std::this_thread::get_id())
        std::cout << "This is the main thread.\n";
    else
        std::cout << "This is no the main thread.\n";
}

int main()
{
    is_main_thread();
    std::thread th(is_main_thread);
    th.join();
    return 0;
}

#include <iostream>
#include <thread>
#include <chrono>

void pause_thread(int n)
{
    std::this_thread::sleep_for(std::chrono::seconds(n));
    std::cout << "pause of " << n << " seconds ended\n";
}

int main()
{
    std::cout << "Spawning and detaching 3 threads...\n";
    std::thread(pause_thread, 1).detach();
    std::thread(pause_thread, 2).detach();
    std::thread(pause_thread, 3).detach();
    std::cout << "Done spawning threads.\n";

    std::cout << "(the main thread will now pause for 5 seconds)\n";
    pause_thread(5);
    return 0;
}
/*
output:
Spawning and detaching 3 threads...
Done spawning threads.
(the main thread will now pause for 5 seconds)
pause of 1 seconds ended
pause of 2 seconds ended
pause of 3 seconds ended
pause of 5 seconds ended
*/

#include <iostream>
#include <thread>

void mythread()
{
    std::cout << "mythread\n";
}

int main()
{
    std::thread foo;
    std::thread bar(mythread);

    std::cout << "Joinable after construction:\n" << std::boolalpha;
    std::cout << "foo: " << foo.joinable() << '\n';
    std::cout << "bar: " << bar.joinable() << '\n';

    if (foo.joinable())
        foo.join();
    if (bar.joinable())
        bar.join();

    std::cout << "Joinable after construction:\n" << std::boolalpha;
    std::cout << "foo: " << foo.joinable() << '\n';
    std::cout << "bar: " << bar.joinable() << '\n';

    return 0;
}
/*
output:
mythread
Joinable after construction:
foo: false
bar: true
Joinable after construction:
foo: false
bar: false
*/