#include <iostream>  
#include <thread>  
#include <mutex>  
#include "my_utils.h"std::mutex mtx; // 全局互斥鎖  
int shared_data = 0; // 共享數據  void increment() {  for (int i = 0; i < 10; ++i) {  std::cout <<"increment lock_guard: "<<"\n";std::lock_guard<std::mutex> lock(mtx); // 在這里鎖定互斥鎖  ++shared_data;  std::cout <<"increment: "<<shared_data<<"\n";SLEEP_FOR_500_MS();}  SLEEP_FOR_500_MS();for (int i = 0; i < 10; ++i) {  std::cout <<"increment lock_guard: "<<"\n";std::lock_guard<std::mutex> lock(mtx); // 在這里鎖定互斥鎖  ++shared_data;  std::cout <<"increment: "<<shared_data<<"\n";SLEEP_FOR_500_MS();}  
}  void decrement() {  for (int i = 0; i < 10; ++i) {  std::cout <<"decrement lock_guard1: "<<"\n";std::lock_guard<std::mutex> lock(mtx); // 在這里鎖定互斥鎖  --shared_data;  SLEEP_FOR_500_MS();std::cout <<"decrement: "<<shared_data<<"\n";}  for (int i = 0; i < 10; ++i) {  std::cout <<"decrement lock_guard2: "<<"\n";std::lock_guard<std::mutex> lock(mtx); // 在這里鎖定互斥鎖  --shared_data;  SLEEP_FOR_500_MS();std::cout <<"decrement: "<<shared_data<<"\n";}  
}  int main() {  std::thread t1(increment);  std::thread t2(decrement);  std::cout << "task inited: " << shared_data << std::endl;  t1.join();  t2.join();  std::cout << "Final value of shared_data: " << shared_data << std::endl;  return 0;  
}

運行結果如下：

increment lock_guard: 
increment: 1
task inited: 1
decrement lock_guard1: 
increment lock_guard: 
increment: 2
increment lock_guard: 
decrement: 1
decrement lock_guard1: 
decrement: 0
decrement lock_guard1: 
decrement: -1
decrement lock_guard1: 
decrement: -2
decrement lock_guard1: 
decrement: -3
decrement lock_guard1: 
decrement: -4
decrement lock_guard1: 
decrement: -5
decrement lock_guard1: 
decrement: -6
decrement lock_guard1: 
decrement: -7
decrement lock_guard1: 
decrement: -8
decrement lock_guard2: 
decrement: -9
decrement lock_guard2: 
decrement: -10
decrement lock_guard2: 
decrement: -11
decrement lock_guard2: 
decrement: -12
decrement lock_guard2: 
decrement: -13
decrement lock_guard2: 
decrement: -14
decrement lock_guard2: 
decrement: -15
decrement lock_guard2: 
decrement: -16
decrement lock_guard2: 
decrement: -17
decrement lock_guard2: 
decrement: -18
increment: -17
increment lock_guard: 
increment: -16
increment lock_guard: 
increment: -15
increment lock_guard: 
increment: -14
increment lock_guard: 
increment: -13
increment lock_guard: 
increment: -12
increment lock_guard: 
increment: -11
increment lock_guard: 
increment: -10
increment lock_guard: 
increment: -9
increment lock_guard: 
increment: -8
increment lock_guard: 
increment: -7
increment lock_guard: 
increment: -6
increment lock_guard: 
increment: -5
increment lock_guard: 
increment: -4
increment lock_guard: 
increment: -3
increment lock_guard: 
increment: -2
increment lock_guard: 
increment: -1
increment lock_guard: 
increment: 0
Final value of shared_data: 0