My string-dynamic-array.cpp file
#include <iostream>
#include <string>
class DynamicArray
{
public:
DynamicArray()
: mCapacity(1), mNumberOfElements(0)
{
mArray = new std::string[mCapacity];
}
DynamicArray(int size)
: mCapacity(size), mNumberOfElements(0)
{
mArray = new std::string[mCapacity];
}
DynamicArray(const DynamicArray& array)
: mCapacity(array.getCapacity()), mNumberOfElements(array.length())
{
mArray = new std::string[mCapacity];
for (size_t i = 0; i < mCapacity; ++i)
{
mArray[i] = array.get(i);
}
}
~DynamicArray()
{
delete[] mArray;
}
void add(std::string element)
{
if (mNumberOfElements >= mCapacity)
{
expand();
}
mArray[mNumberOfElements++] = element;
}
std::string get(int index) const
{
if (index > mNumberOfElements)
{
std::string exception = std::to_string(index) + " index is out of bounds.";
std::cout << exception;
return std::string();
}
if (index < 0)
{
if (mNumberOfElements + index < 0)
{
std::string exception = std::to_string(index) + " index result in " + std::to_string(mNumberOfElements + index) + " which is out of bounds.\n";
std::cout << exception;
return std::string();
}
return mArray[mNumberOfElements + index];
}
return mArray[index];
}
int length() const
{
return mNumberOfElements;
}
int getCapacity() const
{
return mCapacity;
}
private:
int mCapacity;
int mNumberOfElements;
std::string* mArray;
void initialize(int from)
{
for (size_t i = from; i < mCapacity; ++i)
{
mArray[i] = std::string();
}
}
void expand()
{
mCapacity *= 2;
std::string* temporaryArray = new std::string[mCapacity];
for (size_t i = 0; i < mCapacity; ++i)
{
temporaryArray[i] = mArray[i];
}
delete[] mArray;
mArray = temporaryArray;
initialize(mNumberOfElements);
}
};
int main()
{
DynamicArray strings;
strings.add("Hello");
strings.add("World");
for (size_t i = 0; i < strings.length(); ++i)
{
std::cout << strings.get(i) << std::endl;
}
}
My output
$ clang++ tests/string-dynamic-array.cpp -o tests/string-dynamic-array && ./tests/string-dynamic-array
[1] 14950 segmentation fault (core dumped) ./tests/string-dynamic-array
I get a segmentation fault.
The issue as far as I've found is in the code where I expand the array, in the expand() function. I think it's in the for loop because the index of for loop is out of bounds of the original array.
I've tried this with int, it seems to work fine. How can I do this with strings?
As commented by UnholySheep.
I changed my expand function a bit so the loop only runs till the size of the old array.
Updated expand function:
void expand()
{
mCapacity *= 2;
std::string* temporaryArray = new std::string[mCapacity];
for (size_t i = 0; i < mNumberOfElements; ++i)
{
temporaryArray[i] = mArray[i];
}
delete[] mArray;
mArray = temporaryArray;
initialize(mNumberOfElements);
}
In “expand” method you have deleted mArray, then, you copied the temporaryArray to it, while as far as I know, mArray’s handle is not valid anymore. You need to pass temporaryArray‘s handle to mArray so you could use it as a new expanded array.
Related
i have this reSize function in my Array header
void reSize(int newsize) {
T* old = items;
size = newsize;
items = new T[newsize];
for (int i = 0;i < length;i++)
items[i] = old[i];
delete[]old;
}
and my main code:
struct User{
string name;
Array<int> data;
};
int main() {
Array<User> x(3);
x.get(0).name = "Kmal";
x.get(0).data.push_back(2); x.get(0).data.push_back(3);
x.reSize(10);
cout << x.get(0).data.get(0) <<endl;
return 0;
}
the problem is after resizing, my values that were stored in "data" variable are gone.
when i commented the code.
//delete[] old
in the reSize function
it worked fine...so i guess the problem is when i delete the pointer it deletes also the pointer inside the struct object which i don't want it to happen..
i don't want to comment the command becuz a leak in the memory will happen...how to fix this problem ?.
Update: My Array Class .
#include <iostream>
using namespace std;
template <class T>
class Array {
private :
T* items;
int size;
int length;
public :
Array() {
this->size = 0;
items = new T[this->size];
length = 0;
}
Array(int size) {
this->size = size;
items = new T[this->size];
length = 0;
}
int getsize() {
return this->size;
}
template <class T> void push_back(T x) {
if ((length+1) <= size) {
items[length] = x;
length++;
}
else {
this->reSize(size+1);
items[length] = x;
length++;
}
}
template <class T> void Insert(int index, T x) {
if (length + 1 <= size) {
for (int i = length;i > index;i--) {
items[i] = items[i - 1];
}
items[index] = x;
length++;
}
else {
this->reSize(size+1);
for (int i = length;i > index;i--) {
items[i] = items[i - 1];
}
items[length] = x;
length++;
}
}
template <class T> int Find(T x) {
int index = -1;
for (int i = 0;i < length;i++) {
if (items[i] ==x) {
index = i;
break;
}
}
return index;
}
void remove(int index) {
items[index] = "";
if(index+1 < length)
for (int i = index;i < length-1;i++) {
items[i] = items[i + 1];
items[i + 1] = "";
}
length--;
}
void reSize(int newsize) {
T* old = items;
size = newsize;
items = new T[newsize];
for (int i = 0;i < length;i++)
items[i] = old[i];
delete[]old;
}
void Merge(Array<T> x){
T* old = items; int oldlength = length;
items = new T[size + x.size];
size = size + x.size;
length += x.length;
for (int i = 0;i < length;i++) {
if(i< oldlength)
items[i] = old[i];
else
items[i] = x.items[i-oldlength];
}
delete[] old;
}
T& get(int index) {
return items[index];
}
}
struct User{
string name;
Array<int> data;
};
int main() {
Array<User> x(3);
// this line causes some problems
x.get(0).name = "Kmal";
x.get(0).data.push_back(2); x.get(0).data.push_back(3);
x.reSize(10);
cout << x.get(0).data.get(0) <<endl;
return 0;
}
In your code, declaring Array<User> x(3) declares an empty array with 3 elements that are preallocated. The length property of the array is 0. When the array is copied, length(0) elements are copied over into the resized storage. When you access the 0th element, it won't be copied on resize. What you actually need to do is call push_back() to add an element to the array so that length becomes 1 and the element is copied on resize.
Also, your array class is lacking a proper copy constructor and move constructor, which means copying it won't work at all. This means that User cannot be copied properly since it contains an array, which means that resizing an array of User won't work. You need to implement a copy constructor and copy assignment operator to be able to copy the array. You also need a destructor since, right now, the array is leaking memory when it goes out of scope.
Inventory::Inventory()
{
this->cap = 10;
this->nrOfItems = 0;
this->itemArr = new Item* [cap]();
}
Inventory::~Inventory()
{
for (size_t i = 0; i < this->nrOfItems; i++)
{
delete this->itemArr[i];
}
delete[] this->itemArr;
}
void Inventory::expand()
{
this->cap *= 2;
Item **tempArr = new Item*[this->cap]();
for (size_t i = 0; i < this->nrOfItems, i++;)
{
tempArr[i] = new Item(*this->itemArr[i]);
}
for (size_t i = 0; i < this->nrOfItems, i++;)
{
delete this->itemArr[i];
}
delete[] this->itemArr;
this->itemArr = tempArr;
this->initialize(this->nrOfItems);
}
void Inventory::initialize(const int from)
{
for (size_t i = from; i < cap, i++;)
{
this->itemArr[i] = nullptr;
}
}
void Inventory::addItem(const Item& item)
{
if (this->nrOfItems >= this->cap)
{
expand();
}
this->itemArr[this->nrOfItems++] = new Item(item);
}
void Inventory::removeItem(int index)
{
}
Above is my code from Inventory.cpp and the issue is that I keep getting an Unhandled Exception from the line that has:
this->itemArr[i] = nullptr;
I have no idea where I'm messing up in the code. Below I am posting from Inventory.h:
class Inventory
{
private:
int cap;
int nrOfItems;
Item **itemArr;
void expand();
void initialize(const int from);
public:
Inventory();
~Inventory();
void addItem(const Item &item);
void removeItem(int index);
inline void debugPrint() const
{
for (size_t i = 0; i < this->nrOfItems; i++)
{
std::cout << this->itemArr[i]->debugPrint() << std::endl;
}
}
};
This is where itemArr should be housed but for some reason, it is not pulling. I am new to coding so I don't know all of the tips and tricks involved with it.
In the loop i < cap, i++;, you will first check if i is in bounds, and then increase it by one before the loop body executes. Thus if i=cap-1 the check will pass, i will become cap and you're out of bounds.
Instead write (size_t i = from; i < cap;i++), so that the increment of i is executed after the loop body.
A see several problems with your code:
In Inventory::expand(), since you are working with an array of pointers (why not an array of objects?), there is no need to make clones of the existing Item objects to the new array, just copy the existing pointers as-is. You are just expanding the array to fit more pointers, so the clones are wasted overhead. Not a fatal issue, but it is something you should be aware of.
In both Inventory::initialize() and Inventory::expand(), your loops are setup incorrectly. You are performing the i++ in the wrong place. Given this definition of a loop:
for ( <init-statement> <condition> ; <iteration_expression> )
You are performing the i++ as part of the <condition>, not the <iteration_expression>. A simply typo caused by you using the comma operator instead of ;, but an important typo nonetheless.
Inventory is violating the Rule of 3/5/0, by not implementing copy/move constructors and copy.move assignment operators.
With that said, try this instead:
class Inventory
{
private:
size_t cap;
size_t nrOfItems;
Item **itemArr;
void expand();
public:
Inventory();
Inventory(const Inventory &src);
Inventory(Inventory &&src);
~Inventory();
Inventory& operator=(Inventory rhs);
void addItem(const Item &item);
void removeItem(size_t index);
inline void debugPrint() const
{
for (size_t i = 0; i < nrOfItems; ++i)
{
std::cout << itemArr[i]->debugPrint() << std::endl;
}
}
};
Inventory::Inventory()
{
cap = 10;
nrOfItems = 0;
itemArr = new Item*[cap]();
}
Inventory::Inventory(const Inventory &src)
{
cap = src.cap;
nrOfItems = src.nrOfItems;
itemArr = new Item*[cap]();
for(size_t i = 0; i < nrOfItems; ++i)
{
itemArr[i] = new Item(*(src.itemArr[i]));
}
}
Inventory::Inventory(Inventory &&src)
{
cap = src.cap; src.cap = 0;
nrOfItems = src.nrOfItems; src.nrOfItems = 0;
itemArr = src.itemArr; src.itemArr = nullptr;
}
Inventory::~Inventory()
{
for (size_t i = 0; i < nrOfItems; ++i)
{
delete itemArr[i];
}
delete[] itemArr;
}
Inventory& Inventory::operator=(Inventory rhs)
{
Inventory temp(std::move(rhs));
std::swap(cap, temp.cap);
std::swap(nrOfItems, temp.nrOfItems);
std::swap(itemArr, temp.itemArr);
return *this;
}
void Inventory::expand()
{
size_t newCap = cap * 2;
Item **tempArr = new Item*[newCap]();
for (size_t i = 0; i < nrOfItems; ++i)
{
tempArr[i] = itemArr[i];
}
delete[] itemArr;
itemArr = tempArr;
cap = newCap;
}
void Inventory::addItem(const Item& item)
{
if (nrOfItems >= cap)
{
expand();
}
itemArr[nrOfItems] = new Item(item);
++nrOfItems;
}
void Inventory::removeItem(size_t index)
{
if (index < nrOfItems)
{
Item *item = itemArr[index];
for(size_t i = index + 1; i < nrOfItems; ++i)
{
itemArr[i-1] = itemArr[i];
}
--nrOfItems;
itemArr[nrOfItems] = nullptr;
delete item;
}
}
That being said, you really should be using std::vector instead, let it handle these details for you, eg:
#include <vector>
class Inventory
{
private:
std::vector<Item> itemVec;
public:
Inventory();
void addItem(const Item &item);
void removeItem(size_t index);
inline void debugPrint() const
{
for (Item &item : items)
{
std::cout << item.debugPrint() << std::endl;
}
}
};
Inventory::Inventory()
{
itemVec.reserve(10);
}
void Inventory::addItem(const Item& item)
{
itemVec.emplace_back(item);
}
void Inventory::removeItem(size_t index)
{
if (index < itemVec.size())
{
itemVec.erase(itemVec.begin() + index);
}
}
See how much simpler that is? :)
I finished some code that prints out how many times a word shows up. However, when I finished and tried to run the code on a different compiler it did not work. Firstly, here is a picture of my code working on my initial file:
But when I used a different compiler (onlinegdb) I get this error:
The thing that confused me the most is; when I try and replicate the file into a new VS Code .cpp file, it does not work. It runs the code but then prints out nothing. When I went into gdb I find this error:
If anyone knows where the segmentation fault/std::length_error are happening at please let me know, and if you have any recommendations that would be great! Also, knowing why I get different results on the same compiler (VS Code) would also be helpful. Here is my code:
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
class WordOccurrence
{
public:
WordOccurrence(const string& word="", int num=1)
{
word_ = word;
num_ = num;
}
bool matchWord(const string & compare)
{
if(word_ == compare)
return true;
else
return false;
}
void increment()
{
num_++;
}
string getWord() const
{
return word_;
}
int getNum() const
{
return num_;
}
private:
string word_;
int num_;
};
class WordList
{
public:
friend bool equal(const WordList&, const WordList&);
WordList();
WordList(const WordList &);
~WordList();
WordList operator= (const WordList &);
void addWordFile(WordList w);
void addWord(const string &);
void print();
private:
WordOccurrence *wordArray_;
int size_;
};
WordList::WordList()
{
size_ = 0;
wordArray_ = new WordOccurrence [size_];
}
WordList::WordList (const WordList &neww)
{
size_ = neww.size_;
wordArray_ = new WordOccurrence[size_];
for (int i = 0; i <= (size_ - 1); i++)
wordArray_[i] = neww.wordArray_[i];
}
WordList::~WordList ()
{
delete [] wordArray_;
}
WordList WordList::operator= (WordList const &overload)
{
WordList temp(overload);
swap(wordArray_, temp.wordArray_);
swap(size_, temp.size_);
return *this;
}
void WordList::addWord(const string& word)
{
if(size_ == 0)
{
WordOccurrence *first_array = new WordOccurrence[1];
first_array[0] = word;
delete[] wordArray_;
wordArray_ = first_array;
delete[] first_array;
size_++;
return;
}
//if the word is already in the array, we increase the count of it by 1
for (int i = 0; i < size_; i++)
{
if (wordArray_[i].matchWord(word))
{
wordArray_[i].increment();
return;
}
}
//if it is not in the array already, we need to increase its size and then add the new word to the wordarray.
WordOccurrence *new_array = new WordOccurrence[size_+1];
for (int i = 0; i < size_; i++)
{
new_array[i] = wordArray_[i];
}
new_array[size_] = WordOccurrence(word);
delete[] wordArray_;
size_++;
wordArray_ = new_array;
delete[] new_array;
}
void WordList::print()
{
//to output to a file because when we get a lot of words it's kinda hard to see on just the terminal
ofstream myfile ("output.txt");
WordList sortedList(*this);
//Sorting from smallest to largest
int smallest = wordArray_[0].getNum();
for (int i = 1; i < size_; i++)
{
//stores the smallest value into smallest
if(wordArray_[i].getNum() < smallest)
smallest = wordArray_[i].getNum();
}
int location = 0;
//stores values from start to finish in the new list starting at location sortedList[0]
while(location < size_)
{
for(int i = 0; i < size_; i++)
{
//runs through the new list until it finds a value that is apart of the smallest/rarest words
if(wordArray_[i].getNum() == smallest)
{
sortedList.wordArray_[location] = wordArray_[i];
location++;
}
}
//increases the value of smallest allowing for numbers with greater found values to be sorted
smallest++;
}
//prints out the sorted version of wordarray
for(int i = 0; i < size_; i++)
{
string word = sortedList.wordArray_[i].getWord();
int count = sortedList.wordArray_[i].getNum();
cout << "Word: " << word << " Amount: " << count << endl;
//for longer amounts of text, it was hard to see on a editor so I also have it out to a file.
myfile << "Word: " << word << " Amount: " << count << endl;
}
}
int main()
{
WordList w;
w.addWord("one");
w.addWord("one");
w.addWord("two");
w.addWord("three");
w.addWord("four");
w.addWord("four");
w.addWord("four");
w.addWord("four");
w.addWord("five");
w.addWord("five");
w.addWord("five");
cout << "Sorted list" << endl;
w.print();
}
This is bugged
WordOccurrence *first_array = new WordOccurrence[1];
first_array[0] = word;
delete[] wordArray_;
wordArray_ = first_array;
delete[] first_array;
size_++;
return;
You assign first_array to wordArray_ and then you delete it. This leaves wordArray_ as an invalid pointer. Just remove delete[] first_array;. Two deletes and only one new should have been a clue that something was wrong.
Same bug later on in the same function
WordOccurrence *new_array = new WordOccurrence[size_+1];
for (int i = 0; i < size_; i++)
{
new_array[i] = wordArray_[i];
}
new_array[size_] = WordOccurrence(word);
delete[] wordArray_;
size_++;
wordArray_ = new_array;
delete[] new_array;
delete[] new_array; should not be there.
Everything seems to be copying fine, but when I call array2.print(), it shows segmentation fault. What am I doing wrong?
#include <iostream>
#include <initializer_list>
template <typename T>
class DynamicArray
{
private:
const int GROWTH_FACTOR = 2;
const int INITIAL_CAPACITY = 5;
T *m_array;
int m_capacity; // Capacity of the array
int m_size; // Number of added elements
public:
DynamicArray(std::initializer_list<T> elements)
: m_size(elements.size())
, m_capacity(elements.size() * 2)
{
m_array = new T[m_capacity];
std::copy(elements.begin(), elements.end(), m_array);
}
DynamicArray()
: m_size(0)
, m_capacity(INITIAL_CAPACITY)
{
m_array = new T[m_capacity];
}
~DynamicArray()
{
delete[] m_array;
}
DynamicArray(const DynamicArray& other)
: GROWTH_FACTOR(other.GROWTH_FACTOR)
, INITIAL_CAPACITY(other.INITIAL_CAPACITY)
, m_capacity(other.m_capacity)
, m_size(other.m_size)
{
T *m_array = new T[m_capacity];
std::copy(other.m_array, other.m_array + m_size, m_array);
}
int size()
{
return m_size;
}
int capacity()
{
return m_capacity;
}
void resize()
{
int new_capacity = m_capacity * GROWTH_FACTOR;
m_capacity = new_capacity;
T *temp = new T[new_capacity];
std::copy(m_array, m_array + m_capacity, temp);
delete[] m_array;
m_array = temp;
}
void deleteAt(int pos)
{
for (int i = pos; i < m_size - 1; i++)
{
(*this)[i] = (*this)[i + 1];
}
m_size--;
}
void insertAt(T value, int pos)
{
if (m_capacity == m_size)
{
resize();
}
for (int i = m_size - 1; i >= pos; i--)
{
(*this)[i + 1] = (*this)[i];
}
m_size++;
(*this)[pos] = value;
}
void append(T value)
{
insertAt(value, m_size);
}
void print() {
for (int i = 0; i < m_size; i++)
{
std::cout << (*this)[i] << ", ";
}
std::cout << std::endl;
}
T& operator[](int index)
{
if (index < 0 || index > m_size - 1)
{
throw std::invalid_argument("Index out of range!");
}
return m_array[index];
}
};
int main()
{
DynamicArray<int> array = { 1, 2, 3, 4 };
DynamicArray<int> array2 = array;
array2.print();
return 0;
}
The error is here
T *m_array = new T[m_capacity];
It should be
m_array = new T[m_capacity];
By declaring a new variable called m_array you hid the class member variable that you wanted to assign to. The technical name for this is shadowing, a good compiler would warn you about this.
You redeclare m_array in the cctor, which shadows the class member.
I'm trying to work with dynamic arrays. When I try to overload the "=" operator it does not work. When debugging the file it doesn't execute the void function to overload the operator.
#include <iostream>
using namespace std;
class cppArray {
public:
cppArray(int size);
~cppArray();
int read(int index);
void write(int content, int index);
void operator=(cppArray& s);
int search(int target);
int size();
private:
int* myArray;
int arraySize;
};
cppArray::cppArray(int size) {
myArray = new int[size];
arraySize = size;
}
//delete the memory space assigned to myArray
cppArray::~cppArray() {
delete[] myArray;
myArray = 0;
}
int cppArray::read(int index) {
if (index < arraySize) {
return myArray[index];
}
else {
cout << "Out of range" << endl;
exit(1);
}
}
Here I'm trying to copy the content of the original array to an auxiliar one, and then redefine the size of the original array so I can add more content to the original array
void cppArray::write(int content, int index) {
if (index < arraySize) {
myArray[index] = content;
}
else {
cppArray auxArray(arraySize);
auxArray.myArray = myArray;
delete[] myArray;
arraySize = index + 1;
myArray = new int[arraySize];
myArray = auxArray.myArray;
myArray[index] = content;
}
}
I'm pretty sure this is wrong, but I can't figure out a way to overload it correctly
void cppArray::operator=(cppArray& s) {
delete[] s.myArray;
s.myArray = new int[arraySize];
for (int i = 0; i < arraySize; i++)
{
myArray[i] = s.myArray[i];
}
}
int cppArray::size() {
return arraySize;
}
int main(int argc, char** argv) {
cppArray dsArray(3);
dsArray.write(1, 0);
dsArray.write(2, 1);
dsArray.write(3, 2);
dsArray.write(4, 3);
for (int i = 0; i < dsArray.size(); i++) {
cout << dsArray.read(i) << "\t";
}
cout << endl;
return 0;
}```
Your implementation is almost correct, but you delete the wrong array. You should only modify *this object, and not s. Also, you should follow conventions, or people will be very surprised when using your class.
Here's corrected version:
//return *this - a very expected convention
cppArray& cppArray::operator=(const cppArray& s) {
// Make sure s is not modified ^^^^
if (this == &s) {
return *this; //protection against self writing, things would get bad if you did that
}
arraySize = s.arraySize; //copy size first
delete[] myArray; //delete array from this object
myArray = new int[arraySize]; //recreate array
for (int i = 0; i < arraySize; i++)
{
myArray[i] = s.myArray[i]; //no changes here
}
return *this;
}