How to perform C++ multi-threaded programming?

How to perform C multi-thread programming?

With the continuous development of computer hardware, multi-core processors have become the mainstream of modern computers. In order to fully utilize the performance of multi-core processors, multi-threaded programming becomes an important skill. C is a powerful programming language that also provides many tools and libraries for multi-threaded programming. This article will introduce how to do C multi-threaded programming.

1. Introduce header files

Before using C for multi-thread programming, you need to introduce the corresponding header files. Before the C 11 standard, the <pthread.h></pthread.h> header file needed to be introduced to use the POSIX thread library. After the C 11 standard, you can directly use the <thread></thread> header file for multi-threaded programming.

2. Creating a thread

In C, you can use the std::thread class to create a new thread. The basic syntax for creating a thread is as follows:

std::thread threadObj(function, arg1, arg2, ...);

Among them, function is a callable object, which can be a function pointer, a function object or a Lambda expression. arg1, arg2, ... are the parameters passed to function. In this way, you can easily create a new thread and pass it the code that needs to be executed.

3. Thread execution

Threads created by using the std::thread class can call its join()Method to wait for thread execution to complete. The specific syntax is as follows:

threadObj.join();

This line of code will block the current thread until threadObj thread execution is completed.

4. Passing parameters of threads

Threads created through the std::thread class can pass parameters in two ways. One is passing by reference and the other is passing by value. When passing by reference, you need to use the std::ref function to wrap the parameters. The specific syntax is as follows:

std::thread threadObj(function, std::ref(arg1), std::ref(arg2), ...);

When passing by reference, you need to pay attention to the life cycle of the thread. If the main thread ends before the thread execution ends, unpredictable behavior will occur.

5. Use future to get the thread return value

Sometimes, we hope that a value can be returned after the thread execution ends. C provides the std::future class to accomplish this task. First, you need to create an asynchronous task by calling the std::async function, and then get the return value by calling the get() method. The specific syntax is as follows:

std::future<T> futureObj = std::async(std::launch::async, function, arg1, arg2, ...);
T result = futureObj.get();

where T is the type of the return value. std::launch::asyncThe parameter specifies that the task is executed asynchronously, rather than delayed.

6. Thread synchronization

In multi-thread programming, special attention needs to be paid to thread synchronization. When multiple threads access a resource at the same time, race conditions and data races may occur. C provides a variety of thread synchronization mechanisms, such as mutex locks (std::mutex), condition variables (std::condition_variable) and atomic operations (std: :atomic) etc. By using these mechanisms correctly, safe execution of multiple threads can be ensured.

The above is a basic introduction on how to perform C multi-threaded programming. Multithreaded programming is a complex and challenging skill that requires careful design and consideration of various concurrency scenarios. By using the multi-threaded programming tools and libraries provided by C, you can better utilize the computer's hardware resources and improve program execution efficiency and performance. I hope this article can help readers understand and apply C multi-threaded programming more deeply.

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