C++ lambda 表达式在多线程编程中的应用是什么？

#include <thread>

void concurrent_task(int a, int b) {
  std::cout << "Performing concurrent task with " << a << " and " << b << "\n";
}

int main() {
  std::thread t(concurrent_task, 10, 20);
  t.join();  // 等待线程完成
  return 0;
}

#include <vector>
#include <thread>

void process_element(int& el) {
  el *= 2;
}

int main() {
  std::vector<int> v = {1, 2, 3, 4, 5};

  std::vector<std::thread> threads;
  for (int& el : v) {
    threads.push_back(std::thread(process_element, std::ref(el)));
  }

  for (auto& t : threads) {
    t.join();  // 等待所有线程完成
  }

  // 输出处理后的列表
  for (const auto& el : v) {
    std::cout << el << " ";
  }
  std::cout << "\n";

  return 0;
}

#include <thread>

void modify_variable(int& a) {
  a += 1;
}

int main() {
  int a = 10;
  std::thread t(modify_variable, std::ref(a));
  t.join();
  std::cout << "Modified value: " << a << "\n";
  return 0;
}