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  1. #include <iostream>
  2. #include <string>
  3. #include <functional>
  4.  
  5. template <typename T>
  6. void print(T t){
  7. 	std::cout << t<<std::endl;
  8. }
  9.  
  10. template <typename T>
  11. void print(T t,std::function<void(T& t)> transformer){
  12. 	transformer(t);
  13. 	std::cout << t << std::endl;
  14. }
  15.  
  16. template <typename... Params>
  17. void printLabeled(std::string label,Params... params){
  18. 	std::cout << label << ": ";
  19. 	print(params...);
  20. }
  21.  
  22. int main() {
  23. 	//prints the number '1', as expected
  24. 	print(1);
  25.  
  26. 	//prints the number the label "answer" and then the number one
  27. 	printLabeled("answer",1);
  28.  
  29. 	//I intended this to increment 1 to 2 and then print 2,
  30. 	//but I guess the lambda does not get converted to an std::function,
  31. 	//so this doesn't work
  32. 	//print(1,[](int& num){num+=1;});
  33.  
  34. 	//This does was the above line was intended to do
  35. 	print(1,{[](int& num){num+=1;}});
  36.  
  37. 	//I intended this to be the labeled version of the above line,
  38. 	//but for some reason, this doesn't work anymore
  39. 	// printLabeled("answer",1,{[](int& num){num+=1;}});
  40.  
  41. 	//This labeled version does work finally,
  42. 	//but its pretty verbose
  43. 	printLabeled("answer",1,std::function<void(int&)>([](int& num){num+=1;}));
  44. 	return 0;
  45. }
Success #stdin #stdout 0s 3460KB
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1
answer: 1
2
answer: 2
https://ideone.com/SwhUPd
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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