thread自然是boost::thread库的主 角，但thread类的实现总体上是比较简单的，前面已经说过，thread只是一个跨平台的线程封装库，其中按照所使用的编译选项的不同，分别决定使用 Windows线程API还是pthread，或者Macintosh Carbon平台的thread实现。以下只讨论Windows，即使用 BOOST_HAS_WINTHREADS的情况。
thread类提供了两种构造函数：
thread::thread()
thread::thread(const function0<void>& threadfunc)
第 一种构造函数用于调用GetCurrentThread构造一个当前线程的thread对象，第二种则通过传入一个函数或者一个functor来创建一个 新的线程。第二种情况下，thread类在其构造函数中间接调用CreateThread来创建线程，并将线程句柄保存到成员变量m_thread中，并 执行传入的函数，或执行functor的operator ()方法来启动工作线程。
我们可以用以下三种方式启动一个新线程：
1、传递一个工作函数来构造一个工作线程
1 #include <boost/thread/thread.hpp>
2 #include <boost/thread/mutex.hpp>
3 #include <iostream>
4
5 boost::mutex io_mutex;
6
7 void count() // worker function
8 {
9 for (int i = 0; i < 10; ++i)
10 {
11 boost::mutex::scoped_lock lock(io_mutex);
12 std::cout << i << std::endl;
13 }
14 }
15
16 int main(int argc, char* argv[])
17 {
18 boost::thread thrd1(&count);
19 boost::thread thrd2(&count);
20 thrd1.join();
21 thrd2.join();
22
23 return 0;
24 }
25
2 #include <boost/thread/mutex.hpp>
3 #include <iostream>
4
5 boost::mutex io_mutex;
6
7 void count() // worker function
8 {
9 for (int i = 0; i < 10; ++i)
10 {
11 boost::mutex::scoped_lock lock(io_mutex);
12 std::cout << i << std::endl;
13 }
14 }
15
16 int main(int argc, char* argv[])
17 {
18 boost::thread thrd1(&count);
19 boost::thread thrd2(&count);
20 thrd1.join();
21 thrd2.join();
22
23 return 0;
24 }
25
、传递一个functor对象来构造一个工作线程
1 #include <boost/thread/thread.hpp>
2 #include <boost/thread/mutex.hpp>
3 #include <iostream>
4
5 boost::mutex io_mutex;
6
7 struct count
8 {
9 count(int id) : id(id) { }
10
11 void operator()()
12 {
13 for (int i = 0; i < 10; ++i)
14 {
15 boost::mutex::scoped_lock lock(io_mutex); // lock io, will be explained soon.
16 std::cout << id << ": " << i << std::endl;
17 }
18 }
19
20 int id;
21 };
22
23 int main(int argc, char* argv[])
24 {
25 boost::thread thrd1(count(1));
26 boost::thread thrd2(count(2));
27 thrd1.join();
28 thrd2.join();
29 return 0;
30 }
31
2 #include <boost/thread/mutex.hpp>
3 #include <iostream>
4
5 boost::mutex io_mutex;
6
7 struct count
8 {
9 count(int id) : id(id) { }
10
11 void operator()()
12 {
13 for (int i = 0; i < 10; ++i)
14 {
15 boost::mutex::scoped_lock lock(io_mutex); // lock io, will be explained soon.
16 std::cout << id << ": " << i << std::endl;
17 }
18 }
19
20 int id;
21 };
22
23 int main(int argc, char* argv[])
24 {
25 boost::thread thrd1(count(1));
26 boost::thread thrd2(count(2));
27 thrd1.join();
28 thrd2.join();
29 return 0;
30 }
31
、无需将类设计成一个functor，借助bind来构造functor对象以创建工作线程
1 #include <boost/thread/thread.hpp>
2 #include <boost/thread/mutex.hpp>
3 #include <boost/bind.hpp>
4 #include <iostream>
5
6 boost::mutex io_mutex;
7
8 struct count
9 {
10 static int num;
11 int id;
12
13 count() : id(num++) {}
14
15 int do_count(int n)
16 {
17 for (int i = 0; i < n; ++i)
18 {
19 boost::mutex::scoped_lock lock(io_mutex);
20 std::cout << id << ": " << i << std::endl;
21 }
22 return id;
23 }
24 };
25
26 int count::num = 1;
27
28 int main(int argc, char* argv[])
29 {
30 count c1;
31 boost::thread thrd1(boost::bind(&count::do_count, &c1, 10));
32 thrd1.join();
33 return 0;
34 }
2 #include <boost/thread/mutex.hpp>
3 #include <boost/bind.hpp>
4 #include <iostream>
5
6 boost::mutex io_mutex;
7
8 struct count
9 {
10 static int num;
11 int id;
12
13 count() : id(num++) {}
14
15 int do_count(int n)
16 {
17 for (int i = 0; i < n; ++i)
18 {
19 boost::mutex::scoped_lock lock(io_mutex);
20 std::cout << id << ": " << i << std::endl;
21 }
22 return id;
23 }
24 };
25
26 int count::num = 1;
27
28 int main(int argc, char* argv[])
29 {
30 count c1;
31 boost::thread thrd1(boost::bind(&count::do_count, &c1, 10));
32 thrd1.join();
33 return 0;
34 }
其中bind是一个函数模板，它可以根据后面的实例化参数构造出一个functor来，上面的boost中是一样的了。