std::function vs function pointer

Question

• Is there any differences?

• Which is the best way to "save/transfer" function?

  function<void(int)> fcn = 
                      [](int par) {std::cout<<"fcn: "<<par<<std::endl; };
  void(*fcn_a)(int) = 
                      [](int par) {std::cout<<"fcn_a: "<<par<<std::endl; };
  
  
  fcn(12);
  fcn_a(12);
  

Answer 1

std::function is more generic - you can store in it any callable object with correct signature (function pointer, method pointer, object with operator()) and you can construct std::function using std::bind.

Function pointer can only accept functions with correct signature but might be slightly faster and might generate slightly smaller code.