// returning a C-string as a pointer pointing to some dynamic memory

#include <iostream>
#include <iomanip>

using namespace std;

char* subr(char[]);
char* sub2(char[]);

int main()
{

  char name1[] = "George Washington";

  char* p;
  char* q;

  int len;

// This works because << is overloaded for char*
  cout << "The first president was " << name1 
       << " which has " << strlen(name1) << " bytes " << endl;

// *name1 has type char, so this only prints one letter
  cout << "His name starts with " << *name1 << endl << endl;


// Get some dynamic memory 
  len = strlen("Abraham Lincoln");
  cout << "Length is " << len << " bytes, so we need " << len + 1
       << " bytes" << endl;
  p = new char[len+1];

// Load a value into it
  strcpy(p, "Abraham Lincoln");

// This works because << is overloaded for char*
  cout << "Another great president was " << p 
       << " which has " << strlen(p) << " bytes" << endl;

// *p has type char, so this only prints one letter
  cout << "His name starts with " << *p << endl << endl;

// All of these are fine because the memory is pre-allocated
  q = subr(name1);
  cout << q << endl;
  cout << subr(name1) << endl;

  q = subr(p);
  cout << q << endl;
  cout << subr(p) << endl << endl;

// And all of these are fine because the memory is dynamically 
// allocated in the function

  q = sub2(name1);
  cout << q           << " has " << strlen(q) << " bytes" << endl;
  cout << sub2(name1) << " has " << strlen(sub2(name1)) << " bytes" << endl;

  q = sub2(p);
  cout << q           << " has " << strlen(q) << " bytes" << endl;
  cout << sub2(p)     << " has " << strlen(sub2(p)) << " bytes" << endl;

// What you can't do is return a pointer to a local variable in the function
// because that would be a dangling pointer (and the compiler will warn you)

  return 0;
}

// This function returns a pointer to pre-allocated memory
char* subr(char* in_string)
{
  return in_string;
}

// This function returns a pointer to some newly allocated dynamic memory
char* sub2(char* in_string)
{
  char* newp;
  newp = new char[strlen(in_string) + 1];
  strcpy(newp, in_string);
  return newp;
}