How to use a function of own class in for_each method?

Question

Assume I have this class (inherited from std::Vector, it\'s just an example)

#include 

using namespace std;

template 
class C          


        

Answer 1

You need to bind the this pointer:

public:   
void method() 
{
    for_each(this->begin(), this->end(), bind(&C::transformation, this, placeholders::_1));
}

Answer 2

For starters, don't inherit from the standard containers, they are not designed to be inherited (no virtual destructors etc.).

Secondly, and regarding your problem, it's because a pointer to a member function is not the same as a pointer to a function. The reason is that member function has a hidden first parameter which becomes the this pointer in the function. The simplest way to solve it is to make the function static.

Another solution is to use the std::bind function that came with C++11:

for_each(this->begin(), this->end(),
    std::bind(&C::transformation, this, std::placeholders::_1));

If you don't have C++11 (even though you tagged your question as such), then you probably could get something working with std::mem_fun or std::bind1st.

Answer 3

C++11 bind solution:

std::for_each(this->begin(), this->end(),
      std::bind(&C::transformation, this, std::placeholders::_1));

C++11 lambda solution:

std::for_each(this->begin(), this->end(),
      [this] (T& i) { transformation(i); });

C++14 generic lambda solution:

std::for_each(this->begin(), this->end(),
      [this] (auto&& i) { transformation(std::forward<decltype(i)>(i)); });

C++98 bind1st+mem_fun solution:

std::for_each(this->begin(), this->end(),
      std::bind1st(std::mem_fun(&C::transformation), this));

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_{Note: this->begin() and this->end() calls are qualified with this-> only because in the OP's code they are member functions of a templated base class. As such, those names are primirarily searched in a global namespace. Any other occurrence of this is mandatory.}