Convert "this" pointer to string

Question

In a system where registered objects must have unique names, I want to use/include the object's this pointer in the name. I want the simplest way to create ??? where:

std::string name = ???(this);

Answer 1

You could use string representation of the address:

#include <sstream> //for std::stringstream 
#include <string>  //for std::string

const void * address = static_cast<const void*>(this);
std::stringstream ss;
ss << address;  
std::string name = ss.str(); 

Answer 2

You mean format the pointer itself as a string?

std::ostringstream address;
address << (void const *)this;
std:string name = address.str();

Or ... yes, all the other equivalent answers in the time it took me to type this!

Answer 3

#include <sstream>
#include <iostream>
struct T
{
    T()
    {
        std::ostringstream oss;
        oss << (void*)this;
        std::string s(oss.str());

        std::cout << s << std::endl;
    }
};

int main()
{
    T t;
} 

Answer 4

You could use ostringstream the this pointer's address and put that ostringstream's value as string?

Answer 5

A simpler one-liner that doesn't require a whole stringstream:

std::string address = std::to_string((unsigned long long)(void**)this);

Also implied, works with pointers of any time, not just this. Also works if you just need it as an integer:

unsigned long long address = (unsigned long long)(void**)this;

You can replace unsigned long long with a type alias that is provided by the system. On Windows it's uintptr_t.

Answer 6

In a system where registered objects must have unique names, I want to use/include the object's this pointer in the name.

An object's address is not necessarily unique. Example: You dynamically allocate such an object, use it for a while, delete it, and then allocate another such object. That newly allocated object might well have the same the object address as the previous.

There are far better ways to generate a unique name for something. A gensym counter, for example:

// Base class for objects with a unique, autogenerated name.
class Named {
public:
  Named() : unique_id(gensym()) {}
  Named(const std::string & prefix) : unique_id(gensym(prefix)) {}

  const std::string & get_unique_id () { return unique_id; }

private:
  static std::string gensym (const std::string & prefix = "gensym");
  const std::string unique_id;
};  

inline std::string Named::gensym (const std::string & prefix) {
  static std::map<std::string, int> counter_map;
  int & entry = counter_map[prefix];
  std::stringstream sstream;
  sstream << prefix << std::setfill('0') << std::setw(7) << ++entry;
  return sstream.str();
}   

// Derived classes can have their own prefix. For example,
class DerivedNamed : public Named {
public:
  DerivedNamed() : Named("Derived") {}
};