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  1. #include <iostream>
  2. #include <functional>
  3.  
  4. void print(int x) {
  5.     std::cout << x << std::endl;
  6. }
  7.  
  8. int main() {
  9.     int hour_now = 5;
  10.     auto get_hour_now = [&]() { return hour_now; };
  11.  
  12.     auto f1 = [&get_hour_now]() { print(get_hour_now() + 10); }; // Correct
  13.     auto f2 = std::bind(print, get_hour_now() + 10); // Wrong
  14.     auto f3 = std::bind(print, std::bind(std::plus<int>(), get_hour_now(), 10)); // Wrong
  15.     auto f4 = std::bind(print, std::bind(std::plus<int>(), std::bind(get_hour_now), 10)); // Correct
  16.  
  17.     f1();
  18.     f2();
  19.     f3();
  20.     f4();
  21.  
  22.     hour_now = 1000;
  23.  
  24.     f1(); // 1010
  25.     f2(); // 15
  26.     f3(); // 15
  27.     f4(); // 1010
  28.  
  29.     return 0;
  30. }
  31.  
Success #stdin #stdout 0s 3468KB
comments (?)
stdin 
Standard input is empty
stdout 
15
15
15
15
1010
15
15
1010
https://ideone.com/oCueTf
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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