C++ Array values being altered at element 4 after throwing exception - c++

Question

The requirements for the program state that the try/catch must be placed in the main.cpp as below:
cout << "printing the array element by element using: int getElement(int);" << endl;
cout << "(going one too far to test out of range)" << endl;
for(int i=0; i<=LISTSIZE; i++){
try{
elementResult = mylist.getElement(i);
cout << elementResult << endl;
} catch(int e){
cout << "Error: Index out of range." << endl;
}
}
cout << endl;
When it accesses the method:
int MyList::getElement(int passedIndex){
if((passedIndex < 0) || (passedIndex > length -1)){
throw 0;
}
return array[passedIndex];
}
It doesn't seem to matter which variation of throwing I use, my array gets destroyed afterward. It works fine if it stays within bounds, or I work it to not throw from the method (doing the error checking elsewhere), but the requirements state that it has to be that way, so I must be missing something. Full code below:
main.h:
#ifndef MAIN_H
#define MAIN_H
/***********************************
* DO NOT MODIFY THIS FILE OTHER THAN
* TO ADD YOUR COMMENT HEADER
***********************************/
#include <iostream> /* cout, endl */
#include "mylist.h"
#include <stdexcept>
#define LISTSIZE 10
using std::cout;
using std::endl;
int elementResult;
#endif /* MAIN_H */
main.cpp:
#include "main.h"
int main(int argc, char** argv) {
/***********************************
* DO NOT MODIFY THIS FILE OTHER THAN
* TO ADD YOUR COMMENT HEADER AND
* UNCOMMENT THINGS AS YOU COMPLETE
* THE FUNCTIONALITY OF YOUR LIST OBJECT
***********************************/
/* This will create a "list" of size LISTSIZE
* and initialize it to all zeros */
cout << "create and initialize mylist" << endl;
MyList mylist(LISTSIZE);
mylist.printArray();
cout << endl;
/* This will set the list to all 50 */
cout << "set mylist to all 50" << endl;
mylist.setArray(50);
mylist.printArray();
cout << endl;
/* This will fail and set the array to the
* default random 1-10 values */
cout << "attempt to set to random numbers -2 to 4" << endl;
mylist.setRandom(-2,4);
mylist.printArray();
cout << endl;
/* This will fail and set the array to the
* default random 1-10 values */
cout << "attempt to set to random numbers 4 to 4" << endl;
mylist.setRandom(4,4);
mylist.printArray();
cout << endl;
/* This will succeed and set the array to the
* random 1-100 values */
cout << "attempt to set to random numbers 1 to 100" << endl;
mylist.setRandom(1,100);
mylist.printArray();
cout << endl;
/* This will succeed and set the array to the
* random 500-1000 values */
cout << "attempt to set to random numbers 500 to 1000" << endl;
mylist.setRandom(1000,500);
mylist.printArray();
cout << endl;
/* These next two sets will succeed and set the 1st and last
* elements to 1000 and 2000 respectively */
if(mylist.setElement(1000, 0)){
cout << "Element Set" << endl;
} else {
cout << "Element NOT Set" << endl;
}
if(mylist.setElement(2000, LISTSIZE-1)){
cout << "Element Set" << endl;
} else {
cout << "Element NOT Set" << endl;
}
mylist.printArray();
cout << endl;
/* These next two sets will fail and leave the array unmodified */
if(mylist.setElement(9999, -1)){
cout << "Element Set" << endl;
} else {
cout << "Element NOT Set" << endl;
}
if(mylist.setElement(9999, LISTSIZE)){
cout << "Element Set" << endl;
} else {
cout << "Element NOT Set" << endl;
}
mylist.printArray();
cout << endl;
cout << "Testing new and/or modified code..." << endl << endl;
cout << "printing the array element by element using: int getElement(int);" << endl;
cout << "(going one too far to test out of range)" << endl;
for(int i=0; i<=LISTSIZE; i++){
try{
elementResult = mylist.getElement(i);
cout << elementResult << endl;
} catch(int e){
cout << "Error: Index out of range." << endl;
}
}
cout << endl;
mylist.printArray();
cout << "attempting to get element 4000 using: int getElement(int);" << endl;
try{
cout << mylist.getElement(4000) << endl;
} catch(int e){
cout << "Error: Index out of range." << endl;
}
cout << endl;
cout << "printing the array element by element using: int getElement(int,int*);" << endl;
cout << "(going one too far to test out of range)" << endl;
for(int i=0; i<=LISTSIZE; i++){
if(mylist.getElement(i, &elementResult)){
cout << elementResult << endl;
} else {
cout << "Error: Index out of range." << endl;
}
}
cout << endl;
cout << "attempting to get element 4000 using: int getElement(int,int*);" << endl;
if(mylist.getElement(4000, &elementResult)){
cout << elementResult << endl;
} else {
cout << "Error: Index out of range." << endl;
}
return 0;
}
mylist.h:
#ifndef MYLIST_H
#define MYLIST_H
#include <iostream> /* cout, endl */
#include <stdlib.h> /* srand, rand, atoi */
#include <time.h> /* time */
#include <stdexcept>
// you can add libraries if you need them, but you shouldn't
// DO NOT MODIFY THESE DEFINES
#define RMIN 1
#define RMAX 10
#define DEFAULT_SIZE 10
using std::cout;
using std::endl;
class MyList {
public:
// DO NOT MODIFY THESES NEXT TWO
MyList(int); // constructor
~MyList(); // destructor
int getElement(int);
void setArray(int);
bool setElement(int, int);
void setRandom(int, int);
void printArray();
bool getElement(int, int*);
private:
// these are the only attributes allowed
// DO NOT ADD OR MODIFY THEM
int length;
int *array;
};
#endif //MYLIST_H
mylist.cpp:
#include "mylist.h"
// constructor
MyList::MyList(int size) {
srand(time(NULL)); // call only once!
if(size < 1){
size = DEFAULT_SIZE;
}
MyList::length = size;
MyList::array = new int(size);
setArray(0);
}
// destructor
MyList::~MyList() {
//delete[] MyList::array;
}
void MyList::printArray() {
cout << "[";
for (int i = 0; i < length; i++){
if (i == length - 1){
cout << array[i];
}else{
cout << array[i] << " ";
}
}
cout << "]" << endl;
}
void MyList::setArray(int setArrayTo){
for (int i = 0; i < length; i++){
MyList::array[i] = setArrayTo;
}
}
void MyList::setRandom(int numOne, int numTwo){
bool isValidRandom = true;
int randMin, randMax;
if((numOne < RMIN) || (numTwo < RMIN) || (numOne == numTwo)){ isValidRandom = false; }
if(isValidRandom == true){
if(numTwo < numOne){
randMin = numTwo;
randMax = numOne;
} else {
randMin = numOne;
randMax = numTwo;
}
} else {
randMin = RMIN;
randMax = RMAX;
}
for(int i = 0;i < length; i++){
MyList::array[i] = rand() % randMax + randMin;
}
}
bool MyList::setElement(int passedValue, int arrayIndex){
bool isInRange = true;
if ((arrayIndex < 0)||(arrayIndex > length - 1)){
isInRange = false;
}
if (isInRange == true){
MyList::array[arrayIndex] = passedValue;
}
return isInRange;
}
int MyList::getElement(int passedIndex){
if((passedIndex < 0) || (passedIndex > length -1)){
throw 0;
}
return array[passedIndex];
}
bool MyList::getElement(int passedIndex, int *iPtr){
bool isItValid = true;
if((passedIndex >= 0) && (passedIndex < length)){
*iPtr = MyList::array[passedIndex];
} else {
isItValid = false;
}
return isItValid;
}
Output