C++ How do I start this? Using an appropriate definition of ListNode, design a s
ID: 3673935 • Letter: C
Question
C++
How do I start this?
Using an appropriate definition of ListNode, design a simple linked list class called StringList with the following member functions:
void add (std::string);
int positionOf (std::string);
bool setNodeVal(int, std::string);
std::vector<std::string> getAsVector();
a default constructor
a copy constructor
a destructor
The add() function adds a new node containing the value of the parameter to the end of the list. The positionOf() function returns the (zero-based) position in the list for the first occurrence of the parameter in the list, or -1 if that value is not in the list. In the setNodeVal() function, the first parameter represents a (zero-based) position in the list. The setNodeVal() function sets the value of the node at that position to the value of the string parameter. If the position parameter is >= the number of nodes in the list, the operation cannot be carried out and setNodeVal() should return false, otherwise it should be successful and return true. The getAsVector() function returns a vector with the same size, values and order as the StringList. The default constructor should initialize a new empty StringList object. The copy constructor should create a completely separate duplicate of a StringList object (a deep copy). The destructor should delete any memory that was dynamically allocated by the StringList object.
Files must be called: StringList.hpp and StringList.cpp
Explanation / Answer
StringList.hpp
#ifndef STRING_LIST
#define STRING_LIST
#include <string>
#include <vector>
class StringList
{
private:
struct ListNode
{
std::string parameter;
ListNode *next;
ListNode(std::string parameter1, ListNode *next1 = NULL)
{
parameter = parameter1;
next = next1;
}
};
ListNode *head;
public:
StringList();
~StringList();
StringList(const StringList &);
void add(std::string);
int positionOf(std::string);
bool setNodeVal(int, std::string);
std::vector<std::string>getAsVector();
};
#endif
StringList.cpp
#include "StringList.hpp"
#include <string>
#include <vector>
#include <iostream>
StringList::StringList() // default constructor
{
head = NULL;
}
StringList::StringList(const StringList& source) // copy constructor
{
head = NULL;
ListNode *p = source.head;
while(p!=NULL)
{
add(p->parameter);
p = p->next;
}
}
void StringList::add(std::string para)
{
if (head == NULL)
head = new ListNode(para);
else
{
ListNode *nodePtr = head;
while (nodePtr->next != NULL) // walks down the list until pointer equals NULL
nodePtr = nodePtr->next;
nodePtr->next = new ListNode(para); // actually adds new node to end
}
}
int StringList::positionOf(std::string value)
{
ListNode *nodePtr = head;
int length = 0;
while (nodePtr != NULL)
{
if (nodePtr->parameter == value)
return length;
else
nodePtr = nodePtr->next;
length++;
}
return -1;
}
bool StringList::setNodeVal(int position, std::string value)
{
ListNode *nodePtr = head;
int count = 0;
while (nodePtr != NULL)
{
if (count == position)
{
nodePtr->parameter = value;
return true;
}
count++;
nodePtr = nodePtr->next;
}
return false;
}
std::vector<std::string> StringList::getAsVector()
{
std::vector<std::string> stringVec;
StringList obj;
ListNode *nodePtr = head;
while (nodePtr != NULL)
{
stringVec.push_back(nodePtr->parameter);
nodePtr = nodePtr->next;
}
return stringVec;
}
StringList::~StringList()
{
ListNode *nodePtr = head;
while(nodePtr != NULL)
{
ListNode *temp = nodePtr;
nodePtr = nodePtr->next;
delete temp;
}
}
main.cpp
#include <iostream>
#include <vector>
#include <string>
#include "StringList.hpp"
using namespace std;
int main() {
StringList list;
list.add("Hello");
list.add("World");
list.add("Goodbye");
cout << "This is the position of Hello in the list: " << list.positionOf("Hello") << endl;
if (list.setNodeVal(0, "Hi"))
{
cout << "setNodeVal has returned true" << endl;
}
if (list.setNodeVal(6, "Hi") == false)
{
cout << "setNodeVal has returned false" << endl;
}
cout << "I changed Hello to Hi at position: " << list.positionOf("Hi") << endl;
StringList newlist = list;
vector<string> veclist = newlist.getAsVector();
for (int i = 0; i < 3; i++)
{
cout << veclist[i] << endl;
}
cout << "This is the position of something in the new list: " << newlist.positionOf("Goodbye") << endl;
return 0;
}
sample output
This is the position of Hello in the list: 0
setNodeVal has returned true
setNodeVal has returned false
I changed Hello to Hi at position: 0
Hi
World
Goodbye
This is the position of something in the new list: 2
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