make -k main  && cat main.cpp && ./main 
g++     main.cpp   -o main
/* #ident "$Id: main.cpp$"
 * @author: rzr@gna.org - rev: $Author: rzr$
 * Copyright: See README file that comes with this distribution
 *****************************************************************************/

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <cassert>

#define LOG()                                                           \
  std::cout                                                             \
  << __FILE__ << ":" << __LINE__ << ": log: " << __PRETTY_FUNCTION__ << std::endl

class Main
{
public:

  Main() {
    LOG();
    ptr_ = new char[1];
  }

  virtual ~Main() {
    LOG();
    delete( ptr_);
  }

public:

  inline char * getPtr() const {
    LOG();
    return(getPtrNew());
  }

  ///TODO: express: char const * const getPtr() const
  inline  char const * const getPtr(bool isconst/*=true*/) const {
    LOG();
    assert(isconst == true);
    return( getPtrConst() );
  }

public: //or private as you want

  char * getPtrNew()  const {
    LOG();
    return(strdup(ptr_));
  }

  char const * const getPtrConst() const
  {
    LOG();
    return(ptr_);
  }

private:
  char * ptr_;

};


int main()
{
  Main const main;
  {
    LOG();
    char* pnew = main.getPtr();
    delete(pnew);
  }
  {
    LOG();
    Main const main;
    char const * const pconst = main.getPtr(true);
    // no need to delete , main's destructor will do
  }
  {
    LOG();
    char const */* const*/ pconst = main.getPtr(true);
    pconst  = 0; // TODO: should be avoid if prev line use const..
    LOG();
    char const * const pnew = main.getPtr(); // TODO: delete const ?
    delete(pnew);
  }
  return 0;
}

/*

  make -k main && cat main.cpp && ./main 

*/

//#eof "$Id:$"

main.cpp:21: log: Main::Main()
main.cpp:67: log: int main()
main.cpp:33: log: char* Main::getPtr() const
main.cpp:47: log: char* Main::getPtrNew() const
main.cpp:72: log: int main()
main.cpp:21: log: Main::Main()
main.cpp:39: log: const char* const Main::getPtr(bool) const
main.cpp:53: log: const char* const Main::getPtrConst() const
main.cpp:26: log: virtual Main::~Main()
main.cpp:78: log: int main()
main.cpp:39: log: const char* const Main::getPtr(bool) const
main.cpp:53: log: const char* const Main::getPtrConst() const
main.cpp:81: log: int main()
main.cpp:33: log: char* Main::getPtr() const
main.cpp:47: log: char* Main::getPtrNew() const
main.cpp:26: log: virtual Main::~Main()

One track to avoid the cast :

 template<typename T>
  T getPtr() {
    return (0);
  }

MISC

error: assignment of read-only reference