Asynchronous Tasks with std::async, std::future, and std::promise0%

std::string_view: Zero-Copy String Passing

Asynchronous Tasks with std::async, std::future, and std::promise

Advanced13 min read•Updated: 2026-10-22

🔮 Asynchronous Tasks with std::async, std::future, and std::promise

Introduction

Low-level threads (std::thread) do not provide a direct way to return a value to the caller. High-level task-based concurrency via std::async and std::future abstracts thread management and transmits return values or exceptions seamlessly.

⚡ Task-Based Asynchrony with `std::async`

1#include <iostream>
2#include <future>
3#include <chrono>
4 
5// Time-consuming background computation:
6int calculateBatchExamAverages(int batchId) {
7    std::this_thread::sleep_for(std::chrono::milliseconds(200));
8    return batchId * 85; // Simulated computed result
9}
10 
11int main() {
12    std::cout << "Initiating background calculation...\n";
13 
14    // Launch asynchronously in background thread:
15    std::future<int> futureResult = std::async(std::launch::async, calculateBatchExamAverages, 101);
16 
17    std::cout << "Main thread continues rendering UI animations...\n";
18 
19    // .get() waits until the task finishes and retrieves the return value!
20    int score = futureResult.get();
21 
22    std::cout << "Background Task Completed! Result: " << score << "\n";
23    return 0;
24}

🤝 `std::promise` and `std::future` Channel

A std::promise is the sending end of a communication channel, while std::future is the receiving end:

1#include <iostream>
2#include <future>
3#include <thread>
4 
5void worker(std::promise<double> prom) {
6    std::this_thread::sleep_for(std::chrono::milliseconds(100));
7    prom.set_value(98.6); // Transmit result to consumer
8}
9 
10int main() {
11    std::promise<double> prom;
12    std::future<double> fut = prom.get_future();
13 
14    std::jthread t(worker, std::move(prom));
15 
16    std::cout << "Received value from thread: " << fut.get() << "\n";
17    return 0;
18}

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std::string_view: Zero-Copy String Passing

Asynchronous Tasks with std::async, std::future, and std::promise

Advanced13 min read•Updated: 2026-10-22

Study Materials

🔮 Asynchronous Tasks with std::async, std::future, and std::promise

Introduction

⚡ Task-Based Asynchrony with `std::async`

1#include <iostream>
2#include <future>
3#include <chrono>
4 
5// Time-consuming background computation:
6int calculateBatchExamAverages(int batchId) {
7    std::this_thread::sleep_for(std::chrono::milliseconds(200));
8    return batchId * 85; // Simulated computed result
9}
10 
11int main() {
12    std::cout << "Initiating background calculation...\n";
13 
14    // Launch asynchronously in background thread:
15    std::future<int> futureResult = std::async(std::launch::async, calculateBatchExamAverages, 101);
16 
17    std::cout << "Main thread continues rendering UI animations...\n";
18 
19    // .get() waits until the task finishes and retrieves the return value!
20    int score = futureResult.get();
21 
22    std::cout << "Background Task Completed! Result: " << score << "\n";
23    return 0;
24}

🤝 `std::promise` and `std::future` Channel

A std::promise is the sending end of a communication channel, while std::future is the receiving end:

1#include <iostream>
2#include <future>
3#include <thread>
4 
5void worker(std::promise<double> prom) {
6    std::this_thread::sleep_for(std::chrono::milliseconds(100));
7    prom.set_value(98.6); // Transmit result to consumer
8}
9 
10int main() {
11    std::promise<double> prom;
12    std::future<double> fut = prom.get_future();
13 
14    std::jthread t(worker, std::move(prom));
15 
16    std::cout << "Received value from thread: " << fut.get() << "\n";
17    return 0;
18}

Next Lesson

std::string_view: Zero-Copy String Passing

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Thread Signaling with std::condition_variable	std::string_view: Zero-Copy String Passing

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next

🔮 Asynchronous Tasks with std::async, std::future, and std::promise

Introduction

⚡ Task-Based Asynchrony with std::async

🤝 std::promise and std::future Channel

std::string_view: Zero-Copy String Passing

Related Lessons

Practice Quiz

Loading Page Content...

🔮 Asynchronous Tasks with std::async, std::future, and std::promise

Introduction

⚡ Task-Based Asynchrony with std::async

🤝 std::promise and std::future Channel

std::string_view: Zero-Copy String Passing

Related Lessons

Practice Quiz

⚡ Task-Based Asynchrony with `std::async`

🤝 `std::promise` and `std::future` Channel

⚡ Task-Based Asynchrony with `std::async`

🤝 `std::promise` and `std::future` Channel