dlib C++ Library - thread_function_ex.cpp

// The contents of this file are in the public domain. See LICENSE_FOR_EXAMPLE_PROGRAMS.txt
/*
 This is a very simple example that illustrates the use of the
 thread_function object from the dlib C++ Library.
 The output of the programs should look like this:
 45.6
 9.999
 I have no args!
 val: 3
*/
#include <iostream>
#include <dlib/threads.h>
#include <dlib/ref.h>
using namespace dlib;
using namespace std;
void thread_1(double a)
{
 cout << a << endl;
}
void thread_2 ()
{
 cout << "I have no args!" << endl;
}
void thread_increment(double& a)
{
 a += 1;
}
int main()
{
 // create a thread that will call thread_1(45.6)
 thread_function t1(thread_1,45.6);
 // wait for the t1 thread to end
 t1.wait();
 // create a thread that will call thread_1(9.999)
 thread_function t2(thread_1,9.999);
 // wait for the t2 thread to end
 t2.wait();
 // create a thread that will call thread_2()
 thread_function t3(thread_2);
 // Note that we can also use the ref() function to pass a variable
 // to a thread by reference. For example, the thread below adds
 // one to val.
 double val = 2;
 thread_function t4(thread_increment, dlib::ref(val));
 t4.wait(); // wait for t4 to finish before printing val.
 // Print val. It will now have a value of 3.
 cout << "val: " << val << endl;
 // At this point we will automatically wait for t3 to end because
 // the destructor for thread_function objects always wait for their
 // thread to terminate.
}