Segmentation fault c++ Hexadecimal Calculator - c++

Question

I keep getting a segmentation fault when I attempt to add a hex number to the current hex number. Here is the line where I'm getting my segmentation fault(I think):
newHex->insertTail(sum);
Here is the whole program:
#include <iostream>
#include <vector>
#include <stdlib.h>
#include <string>
using namespace std;
#undef NULL
const int NULL = 0;
const char SENTINEL = '#';
typedef int element;
class listnode {
public:
element data;
listnode * next;
};
class LList {
private:
listnode * head;
listnode * tail;
listnode * view;
public:
LList();
~LList();
void read();
listnode* next();
void print();
void insertTail(element val);
void clean();
//void add(LList operand);
//void multiply(LList operand);
element deleteHead();
};
class Calculator {
public:
Calculator();
LList* add(LList& left, LList& right);
//LList* multiply(LList& left, LList& right);
};
Calculator::Calculator() {
};
LList* Calculator::add(LList& left, LList& right) {
int sum, carry = 0, lval = 0, rval = 0;
bool calculating = true;
listnode *leftNode;
listnode *rightNode;
LList* newHex;
while(calculating) {
leftNode = left.next();
rightNode = right.next();
if(leftNode == NULL) {
lval = 0;
}
else
lval = leftNode->data;
if(rightNode == NULL) {
rval = 0;
}
else
rval = rightNode->data;
if(leftNode == NULL && rightNode == NULL) {
calculating = false;
if(carry != 0) {
newHex->insertTail(carry);
}
break;
}
sum = lval + rval + carry;
carry = 0;
if(sum >= 16) {
carry = 1;
sum -= 16;
}
cout << "Segmentation Fault Below :)" << endl;
newHex->insertTail(sum);
}
return newHex;
};
listnode* LList::next() {
listnode* temp = view;
if(temp != NULL)
view = view->next;
if(view == NULL) {
}
return temp;
};
LList::LList(){
head = NULL;
view = NULL;
};
void LList::print() {
listnode * temp;
int i = 0;
string printValues;
temp = head;
while(temp != NULL) {
int var = temp -> data;
char character = ' ';
if(i % 3 == 0 && i != 0)
printValues += ',';
i++;
if(var > 9 && var < 16)
{
character = static_cast <char>(var + 65 - 10);
}else if (var <= 9 && var >= 0)
character = static_cast <char>(var + 48);
printValues += character;
temp = temp -> next;
}
string tempValues;
for(int i = printValues.length() - 1; i >= 0; i--)
tempValues += printValues[i];
cout << tempValues;
cout << endl;
};
void LList::read() {
string userval;
int i;
bool parsing = true;
char curval;
vector <int> values;
clean();
while(parsing) {
cin >> userval;
for(unsigned int i = 0; i < userval.length(); i++) {
curval = userval[i]; //this is your character
if(curval >= 48 && curval <= 57)
values.push_back(static_cast <int>(curval -
48));
if(curval >= 65 && curval <= 70)
values.push_back(static_cast <int>(curval -
65 + 10));
if(curval == ' ')
break;
if(curval == SENTINEL) {
parsing = false;
break;
}
}
}
for(int i = values.size() -1; i >= 0; i--) {
insertTail(values[i]);
}
};
void LList::insertTail(element val) {
listnode * temp;
temp = new listnode;
temp -> data = val;
temp -> next = NULL;
if(head == NULL) {
head = temp;
view = head;
}
else
tail -> next = temp;
tail = temp;
};
void LList::clean() {
while(head != NULL)
deleteHead();
};
void validCommands() {
cout << "Valid commands are:" << endl;
cout << " e enter enter the current ";
cout << "hexadecimal ";
cout << "number from the keyboard" << endl;
cout << " a add add a new hexadecimal ";
cout << "number to the current hex. number" << endl;
cout << " m multiply ";
cout << "multiply a new hexadecimal number ";
cout << "by the current hex. number" << endl;
cout << " h help show this help menu" << endl;
cout << " q quit quit the program" << endl << endl;
};
/*
void LList::multiply(LList operand) {
int left, right, product, carry;
listnode* operandNext = operand.next();
listnode* currentNode = this->head;
while(operandNext != NULL) {
left = operandNext->data;
right = currentNode->data;
product = left * right;
carry = 0;
if(product >= 16) {
product -= 16;
carry = 1;
}
if(currentNode == NULL) {
this->insertTail(left);
}
currentNode->data = product;
currentNode = currentNode->next;
operandNext = operandNext->next;
}
};
*/
element LList::deleteHead() {
listnode * temp;
temp = head;
head = head -> next;
delete temp;
return temp -> data;
};
LList::~LList(){
delete head;
};
int main() {
LList L, add,multiply;
Calculator calc;
L.insertTail(0);
char option;
bool run;
cout << "Hexadecimal Calculator, Ver 1.0.0 \n";
cout << endl;
do {
cout << "Current Hexadecimal number is: ";
L.print();
cout << endl;
cout << "Command (h for help): ";
cin >> option;
cout << endl << endl;
switch(option) {
case 'e' :
cout << "Enter a hexadecimal number ";
cout << "followed by #: ";
L.read();
cout << endl << "Entering completed.";
cout << endl << endl;
break;
case 'a' :
cout << "Adding a new hexadecimal number ";
cout << "to the current hex. number" << endl;
cout << endl;
cout << "Enter a hexadecimal ";
cout << "number, follow by #: ";
add.read();
cout << endl << "Addition completed.";
cout << endl;
L = *calc.add(L, add);
cout << endl;
break;
case 'm' :
cout << "Multiplying a new hexadecimal ";
cout << "number ";
cout << "to the current hex. number" << endl;
cout << endl;
cout << "Enter a hexadecimal ";
cout << "number, follow by #: ";
//multiply.read();
cout << endl << "Multiplication completed.";
cout << endl;
//L.multiply(multiply);
cout << endl;
break;
case 'h' : validCommands();
break;
case 'q' : run = false;
break;
};
} while (run);
exit(0);
}

Answer 1

If I'm not wrong, the problem is newHex, in Calculator::add()
You define a pointer to a LList
LList* newHex;
and you use it
newHex->insertTail(carry);
[...]
newHex->insertTail(sum);
without allocate it.