Question

(C++) Suppose you want to use a linked list where the items stored in the list are strings from the standard library string class, how would you change the node1.h header file?

Header File:

#ifndef MAIN_SAVITCH_NODE1_H
#define MAIN_SAVITCH_NODE1_H
#include <cstdlib> // Provides size_t and NULL

namespace main_savitch_5 {

class node {
public:

// TYPEDEF
typedef double value_type;
// CONSTRUCTOR
node(const value_type& init_data=value_type( ), node* init_link=NULL)

{ data_field = init_data; link_field = init_link; }
// MODIFICATION MEMBER FUNCTIONS
node* link( ) { return link_field; }
void set_data(const value_type& new_data) { data_field = new_data; } void set_link(node* new_link) { link_field = new_link; }

// CONST MEMBER FUNCTIONS
value_type data( ) const { return data_field; } const node* link( ) const { return link_field; }

private:
value_type data_field; node *link_field;

};

// FUNCTIONS for the linked-list toolkit
std::size_t list_length(const node* head_ptr);
void list_head_insert(node*& head_ptr, const node::value_type& entry); void list_insert(node* previous_ptr, const node::value_type& entry); node* list_search(node* head_ptr, const node::value_type& target); const node* list_search

(const node* head_ptr, const node::value_type& target);
node* list_locate(node* head_ptr, std::size_t position);
const node* list_locate(const node* head_ptr, std::size_t position); void list_head_remove(node*& head_ptr);
void list_remove(node* previous_ptr);
void list_clear(node*& head_ptr);
void list_copy(const node* source_ptr, node*& head_ptr, node*& tail_ptr);

} #endif

Answer 1

Here the node1.h will have to specify that the value_type it is holding is of string type instead of the double type.

For Example Here is the changed code:

#include <string>

class node {
public:

// TYPEDEF
typedef string value_type;
// CONSTRUCTOR
node(const value_type& init_data=value_type( ), node* init_link=NULL)

{ data_field = init_data; link_field = init_link; }
// MODIFICATION MEMBER FUNCTIONS
node* link( ) { return link_field; }
void set_data(const value_type& new_data) { data_field = new_data; } void set_link(node* new_link) { link_field = new_link; }

// CONST MEMBER FUNCTIONS
value_type data( ) const { return data_field; } const node* link( ) const { return link_field; }

private:
value_type data_field; node *link_field;

};