Example
In C++, threads are created using the std::thread class. A thread is a separate flow of execution; it is analogous to having a helper perform one task while you simultaneously perform another. When all the code in the thread is executed, it terminates. When creating a thread, you need to pass something to be executed on it. A few things that you can pass to a thread:
- Free functions
- Member functions
- Functor objects
- Lambda expressions
Free function example - executes a function on a separate thread (Live Example):
#include <iostream>
#include <thread>
void foo(int a)
{
std::cout << a << '\n';
}
int main()
{
// Create and execute the thread
std::thread thread(foo, 10); // foo is the function to execute, 10 is the
// argument to pass to it
// Keep going; the thread is executed separately
// Wait for the thread to finish; we stay here until it is done
thread.join();
return 0;
}
Member function example - executes a member function on a separate thread (Live Example):
#include <iostream>
#include <thread>
class Bar
{
public:
void foo(int a)
{
std::cout << a << '\n';
}
};
int main()
{
Bar bar;
// Create and execute the thread
std::thread thread(&Bar::foo, &bar, 10); // Pass 10 to member function
// The member function will be executed in a separate thread
// Wait for the thread to finish, this is a blocking operation
thread.join();
return 0;
}
Functor object example (Live Example):
#include <iostream>
#include <thread>
class Bar
{
public:
void operator()(int a)
{
std::cout << a << '\n';
}
};
int main()
{
Bar bar;
// Create and execute the thread
std::thread thread(bar, 10); // Pass 10 to functor object
// The functor object will be executed in a separate thread
// Wait for the thread to finish, this is a blocking operation
thread.join();
return 0;
}
Lambda expression example (Live Example):
#include <iostream>
#include <thread>
int main()
{
auto lambda = [](int a) { std::cout << a << '\n'; };
// Create and execute the thread
std::thread thread(lambda, 10); // Pass 10 to the lambda expression
// The lambda expression will be executed in a separate thread
// Wait for the thread to finish, this is a blocking operation
thread.join();
return 0;
}
