Code:
#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <fstream>
using namespace std;
class linkedListNode
{
public:
char *value; //char array info portion of node
linkedListNode *nextPtr; //declare pointer to next node in list
linkedListNode(char *val = "", linkedListNode *nxtPtr = 0) //node constructor, default empty string for info portion, 'value'
{
nextPtr = nxtPtr;
value = strdup(val);
}
linkedListNode& operator=(const linkedListNode&); //explicit copy constructor, due to pointers
linkedListNode(const linkedListNode&);//explicit assingment operator, due to pointers
~linkedListNode();//explicitly declared destructor, due to pointers
};
class linkedList
{
public:
linkedList() //constructor setting nodes = 0
{
headPtr = tailPtr = 0;//head and tail = 0
}
~linkedList();//explicit destructor
void add(const linkedListNode& node, int);//function to add a node, used for both createEmptyList, and to add/replace a node
linkedListNode * get(int idx);//uses temp variable to locate node for any function that accesses node in the list
void insertLine(int);//insert(or replace) text in a particular node
void display();//displays list for clearer, more user-friendly interface
void deleteNode();//sets 'value' portion of node = "", doesn't actually delete, but as far as end-user is concerned, it does
void deleteLines();//see above deleteNode() comments, "deletes" multiple lines
void addTextToLine();//appends text to 'value' portion of nodes
void createEmptyList();//creates empty nodes for user to manipulate at beginning of int main()
void listFromFile(ifstream&);
private:
linkedListNode *headPtr, *tailPtr; //head and tail pointers for linked list
};
linkedListNode::linkedListNode(const linkedListNode& l)//copy constructor
{
nextPtr = l.nextPtr; //copy pointer over
value = strdup(l.value);//copy value field over
}
linkedListNode& linkedListNode::operator=(const linkedListNode& l) //assignment op.
{
if(this != &l) //make sure not to assign to itself
{
if(value != 0) //if value portion already has a value assigned
{
free(value); //delete it
}
value = strdup(l.value); //copy existing value to freed field
nextPtr = l.nextPtr; //copy existing pointer to l-value pointer field
}
return *this; //std. w/ass. op.
}
linkedListNode::~linkedListNode()
{
if(value != 0)//if value field has a value
{
value = 0;//to prevent dangling reference problem
}
}
linkedList::~linkedList() //linkedList destructor
{
while(headPtr)//as long as there are more nodes
{
linkedListNode *p = headPtr;//temp variable to traverse list while deleting sequentially
headPtr = headPtr->nextPtr;//make head = next element
delete p; //delete temp, which is old head
}
}
void linkedList::add(const linkedListNode& node, int i) //add/replace blank/existing on line i text w/node->value
{
if(headPtr == 0) //if empty
{
headPtr = new linkedListNode(node); //node = head
tailPtr = headPtr;//node also = tail
}
else //if not empty
{
linkedListNode *current = new linkedListNode(node); //create a tmp node with values of 'node' passed to function
current = headPtr; //start at the head of the list
static int count = 0; //set static counter to 0
while(current->nextPtr) //while nextPtr (next element) exists
{
count++; //increment counter (start at 1, since first element = 1)
if(count == i) //if line number == counter
{
break; //break out of the loop, because this is the line number we want to insert/overwrite
}
else // if (count != i)
{
current = current->nextPtr; //move on down the list, one element at a time
}
}
int j; //new counter int
for(j = 0; j <= i-count; j++) //if sequence wasn't completed with i-loop
{
tailPtr->nextPtr = new linkedListNode(); //go on creating empty nodes
tailPtr = tailPtr->nextPtr; //set tail = to new node just created at end
}
}
}
void linkedList::createEmptyList()//this is done to make nodes available for editing to user
{
if(headPtr)
{
return;
}
linkedListNode node(""); // create an empty node on the stack
for(int i = 1; i < 4; i++) // put 3 copies into the list
{
add(node, i);//add node into position i of list
}
}
void linkedList::addTextToLine()//function for appending data
{
int lineNum;//line number which is to be appended to, input by user
cout << "Which line would you like to append to?" << endl;
cin >> lineNum;//input line number to which data is to be appended
char appTxt[255];//text to be appended
cout << "Enter the text to be appended to line " << lineNum << endl;//prompt user to input text
cin.getline(appTxt, 255);//accept text
linkedListNode *tmp;//create temp node to traverse list to find desired line
tmp = headPtr;//start at beginning of list
for(int i = 1; i <= lineNum; i++)//for loop to go to desired line
{
tmp = tmp->nextPtr;//keep incrementing until desired node found
}
strcat(tmp->value, appTxt);//append text to line after desired line found w/for loop
}
void linkedList::listFromFile(ifstream& inputFile)//get node->value for all nodes from chosen file
{
char valPortion[255];
string valuePortion;//value to be put into node->value for all nodes
for(int iTwo = 1; iTwo <= 5; iTwo++)
{
(getline(inputFile, valuePortion));//while eof marker not found in file, read until
cout << valuePortion;
strcpy(valPortion, valuePortion.c_str());//char *valPortion = strdup(valuePortion.c_str()) copy line from file into valPortion, which will be put into new node
//linkedListNode node(valPortion);//create node w/value = line of text
//add(node, iTwo);//add the above-created node to list
linkedListNode node(valPortion);//access node to be deleted(overwritten)
add(node, iTwo);
}
}
void linkedList::display()//display list to user before modifying, for more user-friendliness
{
linkedListNode *node = headPtr;//new temp node to traverse list, starts at head because will go sequentially displaying values for user
int count = 1; //set counter to 1 and display and increment
while(node)//while there is still a node to display
{
cout << count++ << ": " << node->value << "" << endl;//cout value and increment counter for next node
node = node->nextPtr;//move on down the list
}
}
linkedListNode * linkedList::get(int count)//function to go to desired element, to make manipulation possible
{
linkedListNode *pnode = headPtr;//new temp object to find desired node
while(count--)//easier than for-loop
{
pnode = pnode->nextPtr;//go on to next node until nth node
if(!pnode)//if end of list
{
break;//stop
}
}
return pnode;//get(return) the nth node
}
int main()
{
linkedList l;
l.createEmptyList();
fileGoto:
ifstream inputFile;//input file stream object
ofstream outputFile;//output file stream object
string filename;//name of file to be input by user
cout << "EDIT: enter file name: ";//prompt user for name of file
cin >> filename;//user enters name of file to be written
try//get ready to throw fake exception (skips rest of block, which not necessary if file non-existent) if file not opened for input due to non-existence
{
inputFile.open(filename.c_str());//open the chosen file
if(inputFile.fail())//if file does not exist
throw 1;//throw so as to not execute below statements
char overWrite;//y or n overwrite prompt to user
cout << "A file by that name already exists. Would you like to overwrite it? ('y' or 'n'): ";
cin >> overWrite;//user inputs yes or no, y or n
cin.ignore();//flush buffer
if(tolower(overWrite) == 'y')
{
//linkedList l;//create linkedList object l
l.listFromFile(inputFile);//get list from file and set data in file = node->value for all of the nodes
goto ifFromFile;//had this set up so as to not declare linkedList l twice, but didn't like me skipping instantiation w/control statement
}
else if(tolower(overWrite) == 'n')
{
inputFile.close();//close file up
cout << "OK, file will not be overwritten";
goto fileGoto;//go back to file prompt
}
}
catch(int e) {};//do nothing with artificially thrown exception
cin.ignore();//flush buffer after cin statement, since cin and getline used in same program
//create a linkedList object to use linkedList functions
//create empty list to make possible user manipulation of nodes
ifFromFile:
int x = 2;//used to create infinite loop(see use of 'while(x < 4)' below
here://if user inputs invalid data in list options, will cout error message, then return control here
char selection;//for operation to perform
cout << "Which option would you like to perform? " << endl;
cout << "'i' to insert new data or replace existing data;" << endl;
cout << "'d' to delete existing data;" << endl;
cout << "'a' to append to data;" << endl;
cout << "'e' to exit program;" << endl;
cout << "Enter your selection: ";
cin >> selection;//user selects operation to perform
cin.ignore();//get rid of buffer, because I'm using cin and getline in same program
if(tolower(selection) == 'i')
{
while(x < 4)//here's where I create an endless loop until 'n' entered, then use control variable to move back to options list
{
char data[256];//for data to be inserted
int i;//line number to be entered
char response;//y or n response to insert prompt
l.display();//display list for user-friendliness
insGoto://control statement to return to if invalid data input (after warning message displayed)
cout << "Would you like to insert/replace data? ('y' or 'n'): ";
cin >> response;//y or n
cin.ignore();//flush buffer
if(tolower(response) == 'n')
goto here;//if no more data to be entered, go back to options list
else if(tolower(response) == 'y')//if data to be entered
{
cout << "Enter the line number you would like to insert/replace: ";
cin >> i;//user inputs line number
cin.ignore();//flush buffer
cout << endl;
linkedListNode *pnode = l.get(i-1);//go to the desired node
if(pnode)//if node exists
{
cout << "Adding/replacing node " << i << " : ";
cin.getline(data, 256);//get data to be inserted
*pnode = linkedListNode(data, pnode->nextPtr);//write new data to node
}
}
else//if y, Y, n or N not input
{
cout << "Sorry, invalid input. Please answer 'y' or 'n'." << endl;
goto insGoto;//go back to input/replace prompt
}
}
}
else if(tolower(selection) == 'd')//if delete desired
{
while(x < 4)//create endless loop user can break out of by entering 'n'
{
l.display();//display contents of list for user-friendliness
char delYN;//y or n if they want to delete node
delGoto://control statement to go to if invalid delYN response entered
cout << "Would you like to delete any of this info? (y or n): ";
cin >> delYN;//user decided yes or no
if(tolower(delYN) == 'n')
goto here;//if no more info to be input, go back to main menu
else if(tolower(delYN) == 'y')
{
char multLines;//user decides if just 1 line, or more than one to be deleted
cout << "Would you like to delete 1 line, or multiple (1 or m)?: ";
cin >> multLines;//1 or more, user picks
cin.ignore();//flush buffer
if(multLines == '1')//if only 1 line to be deleted
{
int nodeNum;//line/node to be deleted
cout << "Enter the node you would like to delete: ";//prompt user
cin >> nodeNum;//user input
linkedListNode *dnode = l.get(nodeNum-1);//access node to be deleted(overwritten with "")
if(dnode)//if node exists
{
cout << "Node " << nodeNum << " : "
<< dnode->value << "" << " deleted ";
dnode->value = "";//overwrite with "", so user can still access node for manipulation
cout << endl;
}
}
else if(tolower(multLines) == 'm')//if more than one line is to be deleted
{
int startLine, endLine;//line to start deleting, line to stop deleting
cout << "Where do you want to start deleting, which line?: ";
cin >> startLine;//start here
cin.ignore();//flush buffer
cout << "Where do you want to stop deleting, which line?: ";
cin >> endLine;//stop here
cin.ignore();//flush buffer
for(int k = startLine; k <= endLine; k++)//for loop to delete(overwrite) desired lines
{
linkedListNode *dnode = l.get(k-1);//access node to be deleted(overwritten)
if(dnode)//if node exists
{
dnode->value = "";//overwrite it - keep it for user access later, don't delete completely
cout << endl;
}
}
}
else//if neither y nor n input
{
cout << "Sorry, that was incorrect input. Please enter either y or no." << endl;
goto delGoto;
}
}
}
}
else if(tolower(selection) == 'a')//if append(concatenate) operation desired
{
while(x < 4)//endless loop only user breaks out of by selecting 'n'
{
l.display();//display list again for user-frienliness
char appYN;//for deciding whether or not to continue w/append operation
appGoto://goto control statement if user inputs invalid data (neither y nor n)
cout << "Would you like to append to any of this info? (y or n): ";
cin >> appYN;//y or n
if(tolower(appYN) == 'n')
goto here;//go back to main menu if done appending
else if(tolower(appYN) == 'y')
{
cout << "Enter the line number to which you would like to append?: ";
int appLine;//line to be appended
cin >> appLine;//user inputs line #
cin.ignore();//flush buffer
cout << endl;
char appTxt[255];//text to be concatenated
linkedListNode *pnode = l.get(appLine-1);//access node to which we wish to append text
if(pnode)//if node exists
{
cout << "Enter the text to be appended to line " << appLine << ": ";
cin.getline(appTxt, 255);//user inputs text to be concatenated
strcat(pnode->value, appTxt);//concatenate text to value portion of node
}
}
else//if neither y nor n entered to appendText prompt
{
cout << "Sorry, wrong input. Please enter 'y' or 'n'." << endl;
goto appGoto;//go back to appText y or n prompt
}
}
}
else if(tolower(selection) == 'e')//if exit from program desired
{
outputFile.open(filename.c_str());//open outfile object for writing to chose file
for(int n = 1; n <= 5; n++)//for-loop to write out each node's info portion to file
{
linkedListNode *onode = l.get(n-1);//access node to be deleted(overwritten)
if(onode)//if node exists
{
outputFile << onode->value << endl;//write the value portion the the file for access next time opened
}
}
outputFile.close();//close file before exiting program
exit(1);//exit program
}
else//if none of options from main menu chosen
{
cout << "Sorry, wrong input. Choose a selection from the menu " << endl;
goto here;//go back to main meun
}
return 0;
}
