What are the application scenarios for async in C++?

In C++, the async function is used to execute a task in the background and return a std::future object that can be used to retrieve the result of the task. Potential use cases for async include, but are not limited to:

1. Concurrent task execution: By using async functions, multiple tasks can be executed in parallel, improving the performance of the program. Tasks can be executed simultaneously in multiple threads, reducing overall execution time.
2. Asynchronous task execution: In some cases, it is necessary to perform certain tasks in the background of a program to avoid blocking the main thread. By using async functions, tasks can be executed in the background and results can be retrieved when needed.
3. Asynchronous invocation of remote functions: By using async functions, you can call remote functions or services asynchronously, thereby improving the responsiveness of the program.
4. Handle large amounts of data in parallel: When dealing with a large volume of data, using async functions can help process the data in parallel, speeding up the processing time.
5. Use std::future and std::promise for asynchronous communication: the async function returns a std::future object, which can be used to retrieve the result of the task execution. Additionally, you can also use a std::promise object to set the result of the task execution, which can then be retrieved by the std::future object.