急!一个C++问题!希望大家能帮个忙!谢谢

//此程序是建立链表相关的操作
#include <iostream>
#include <string>
using namespace std;//申明结构

struct Elephant
{
string name;
Elephant* next;
};

void print_elephants( const Elephant* ptr );
Elephant* get_elephants();
void free_list( const Elephant* ptr );

int main()
{
Elephant* start;
start = get_elephants();
print_elephants( start );//由于start是指针类型,作为此函数的参数,会在此函数的作用下,start所指向的内存地址会改变,当此函数返回时,start已经为0
free_list( start ); //因此,当再调free_list(start)时,按理说应该不有任何作用了,但此函数还是被调用了!也就是说此时start还是start=get_elephants(),这是为什么啊?
return 0;
}

Elephant* get_elephants()//创建链表
{
Elephant *current,*first;
int response;
current =first=new Elephant;
cout << "\nNAME: ";
cin >> current -> name;
cout << "\nAdd another? (1 == yes, 0 == no): ";
cin >> response;
while ( response == 1 )
{
current = current -> next = new Elephant;
cout << "\nNAME: ";
cin >> current -> name;
cout << "\nAdd another? (1 == yes, 0 == no): ";
cin >> response;
}
current -> next = 0;
return first;
}


void print_elephants( const Elephant* ptr )//打印
{
int count = 1;
cout << "\n\n\n";
while ( ptr != 0 ) {
cout << "Elephant number " << count++
<< " is " << ptr -> name << '\n';
ptr = ptr -> next;
}
}

void free_list( const Elephant* ptr )//释放
{
const Elephant* temp_ptr;
while ( ptr != 0 )
{
cout<<"1111111111111111"<<endl;
temp_ptr = ptr -> next;
delete ptr;
ptr = temp_ptr;
}
}


希望高手们能帮个忙,小弟我不胜感谢!