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  1. #include <cstdlib>
  2. #include <chrono>
  3. #include <iostream>
  4. #include <thread>
  5.  
  6. int p = 0;
  7. int *q = nullptr;
  8.  
  9. void g()
  10. {
  11.     using namespace std::chrono_literals;
  12.  
  13.     std::cout << "g()" << std::endl;
  14.  
  15.     std::cout << "g(): p = 1" << std::endl;
  16.     p = 1;
  17.  
  18.     std::this_thread::sleep_for(1s);
  19.  
  20.  
  21.     if (q != nullptr) {
  22.         std::cout << "g(): *q = 1" << std::endl;
  23.         *q = 1;
  24.     } else {
  25.         std::cout << "g(): q == nullptr" << std::endl;
  26.     }
  27. }
  28.  
  29. void f()
  30. {
  31.     using namespace std::chrono_literals;
  32.  
  33.     std::cout << "f()" << std::endl;
  34.  
  35.     if (p == 0) {
  36.         std::cout << "f(): first loop start" << std::endl;
  37.         while (p == 0) { }  // Потенциально конечный
  38.         std::cout << "f(): first loop end" << std::endl;
  39.     }
  40.  
  41.     int i = 0;
  42.     q = &i;
  43.     std::cout << "f(): second loop start" << std::endl;
  44.     while (i == 0) { }  // Потенциально конечный, хотя в условии только автоматическая пельменная
  45.     std::cout << "f(): second loop end" << std::endl;
  46. }
  47.  
  48. int main()
  49. {
  50.     using namespace std::chrono_literals;
  51.  
  52.     std::cout << "f() thread start" << std::endl;
  53.     auto thr1 = std::thread(f);
  54.     thr1.detach();
  55.     std::this_thread::sleep_for(1s);
  56.  
  57.     std::cout << "g() thread start" << std::endl;
  58.     auto thr2 = std::thread(g);
  59.     thr2.detach();
  60.     std::this_thread::sleep_for(2s);
  61.  
  62.     std::cout << "Done" << std::endl;
  63.  
  64.     std::_Exit(EXIT_SUCCESS);
  65. }
  66.  
Success #stdin #stdout 3s 4192KB
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stdin
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Standard input is empty
stdout
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f() thread start
f()
f(): first loop start
g() thread start
g()
g(): p = 1
g(): q == nullptr
Done
https://ideone.com/OCJQg9
language:
C++14 (clang 8.0)
created:
5 years ago
visibility:
public

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