operators overloading, odd seg fault, classes, c++ - c++

Question

I was given an exercise on overloading operators by my tutor. He gave me the int main() function which cannot be changed. I was supposed to write the functions etc so that the code would work. Unfortunately I have a seg fault. I've noticed that if the
TSeries series4=series1(2,4);
cout << "Series4: " << series4 << endl;
lines are commented it's more or less working. I would be very grateful for your help.
#include <iostream>
class TSeries {
public:
TSeries()
{
_size = 0;
_capacity = 0;
_tab = NULL;
}
TSeries(float *tab, const int size)
{
_tab = new float[size];
for (int i = 0; i < size; i++) _tab[i] = tab[i];
_size = size;
_capacity = 0;
}
~TSeries() { delete[] _tab; }
TSeries & operator+=(float value) { return insert(value); }
TSeries & operator,(float value) { return insert(value); }
TSeries & operator+(const TSeries & s)
{
// if(this->_size != s._size) std::cout<<"Size doesn't match!"<<std::endl;
/*else
{
std::cout<<"whee";
for(int i; i<this->_size;i++)
{
//this->_tab[i] += s._tab[i];
std::cout<<"nothing";
}
return *this;
}*/
//std::cout<<"sth";
}
TSeries & operator()(int position1, int position2)
{
// return *this;
}
TSeries & insert(float k)
{
if (_size >= _capacity) Enlarge();
_tab[_size++] = k;
return *this;
}
friend std::ostream & operator<<(std::ostream & out, const TSeries & s);
private:
int _size, _capacity;
float *_tab, *_itr;
static int _nr;
void Enlarge()
{
_capacity = 2 * _capacity + 1;
float *tmp = new float[_capacity];
for (int i = 0; i < _size; ++i)
{
tmp[i] = _tab[i];
}
delete[] _tab;
_tab = tmp;
}
};
std::ostream & operator<<(std::ostream & out, const TSeries & s)
{
int przedostatni = s._size - 1;
out << "(";
for (int i = 0; i < s._size; i++)
{
out << (int)s._tab[i];
if (i != przedostatni)
out << ",";
}
out << ")" << std::endl;
}
using namespace std;
int main(int argc, char **argv) {
TSeries series1;
series1 += 1., 2., 4., 2.;
cout << "Series1: " << series1 << endl;
const int size = 7;
float tab[size] = { 3.,3.,3.,4.,5.,1.,0. };
const TSeries series2(tab, size);
cout << "Series2: " << series2 << endl << endl;
TSeries series3 = series1 + series2;
cout << "Series3: " << series3 << endl << endl;
series1 += 1., 0., 3.;
series3 = series1 + series2;
cout << " " << series1 << endl;
cout << " +" << series2 << endl;
cout << " ---------------------" << endl;
cout << "Series3: " << series3 << endl << endl;
TSeries series4 = series1(2, 4);
cout << "Series4: " << series4 << endl;
return 0;
}
/* output required:
Series1: (1,2,4,2)
Series2: (3,3,3,4,5,1,0)
Size doesn't match!
Series3: ()
(1,2,4,2,1,0,3)
+(3,3,3,4,5,1,0)
---------------------
Series3: (4,5,7,6,6,1,3)
Series4: (4,2)
*/

Answer 1

std::ostream & operator<<(std::ostream & out, const TSeries & s) doesn't return anything. Please add a return out at the end of the function
operator() and operator+ should both end with return *this
As Devolus already pointed out: You don't have a copy constructor and no operator=(const TSeries&) defined
You can use memcpy to copy the arrays faster.#
The i in the for-loop in operator+(const TSeries&) isn't initialized.
Your operator(int, int) does currently alter the original object. This doesn't seem right.
Code:
#include <iostream>
class TSeries {
public:
TSeries()
{
_size = 0;
_capacity = 0;
_tab = NULL;
}
TSeries(float *tab, const int size)
{
_size = size;
_capacity = 0;
_tab = new float[size];
memcpy(_tab, tab, _size*sizeof(float));
}
TSeries(const TSeries& other)
{
_size = other._size;
_capacity = other._capacity;
_tab = new float[_size];
memcpy(_tab, other._tab, _size*sizeof(float));
}
~TSeries()
{
delete[] _tab;
}
TSeries & operator+=(float value) { return insert(value); }
TSeries & operator,(float value) { return insert(value); }
TSeries & operator+(const TSeries & other)
{
if (this->_size != other._size)
{
std::cout << "Size doesn't match!" << std::endl;
}
else
{
//std::cout << "whee";
for (int i = 0; i < this->_size; i++)
{
_tab[i] += other._tab[i];
//std::cout << "nothing";
}
}
//std::cout<<"sth";
return *this;
}
TSeries& operator=(const TSeries& other)
{
_size = other._size;
_capacity = other._capacity;
//Create tmp in case of self-assignment
float *tmp = new float[_capacity];
memcpy(tmp, other._tab, _size*sizeof(float));
delete[] _tab;
_tab = tmp;
return *this;
}
TSeries operator()(int position1, int position2)
{
//TODO: Range-Check
return TSeries(_tab + position1, position2 - position1);
}
TSeries & insert(float k)
{
if (_size >= _capacity) Enlarge();
_tab[_size++] = k;
return *this;
}
friend std::ostream & operator<<(std::ostream & out, const TSeries & s);
private:
int _size, _capacity;
float *_tab, *_itr;
static int _nr;
void Enlarge()
{
_capacity = 2 * _capacity + 1;
float *tmp = new float[_capacity];
memcpy(tmp, _tab, _size*sizeof(float));
delete[] _tab;
_tab = tmp;
}
};
std::ostream & operator<<(std::ostream & out, const TSeries & s)
{
int przedostatni = s._size - 1;
out << "(";
for (int i = 0; i < s._size; i++)
{
out << (int)s._tab[i];
if (i != przedostatni)
out << ",";
}
out << ")" << std::endl;
return out;
}
using namespace std;
int main(int argc, char **argv) {
TSeries series1;
series1 += 1., 2., 4., 2.;
cout << "Series1: " << series1 << endl;
const int size = 7;
float tab[size] = { 3.,3.,3.,4.,5.,1.,0. };
const TSeries series2(tab, size);
cout << "Series2: " << series2 << endl << endl;
TSeries series3 = series1 + series2;
cout << "Series3: " << series3 << endl << endl;
series1 += 1., 0., 3.;
series3 = series1 + series2;
cout << " " << series1 << endl;
cout << " +" << series2 << endl;
cout << " ---------------------" << endl;
cout << "Series3: " << series3 << endl << endl;
TSeries series4 = series1(2, 4);
cout << "Series4: " << series4 << endl;
return 0;
}
/* output required:
Series1: (1,2,4,2)
Series2: (3,3,3,4,5,1,0)
Size doesn't match!
Series3: ()
(1,2,4,2,1,0,3)
+(3,3,3,4,5,1,0)
---------------------
Series3: (4,5,7,6,6,1,3)
Series4: (4,2)
*/
Output
Series1: (1,2,4,2)
Series2: (3,3,3,4,5,1,0)
Size doesn't match!
Series3: (1,2,4,2)
(4,5,7,6,6,1,3)
+(3,3,3,4,5,1,0)
---------------------
Series3: (4,5,7,6,6,1,3)
Series4: (7,6)
UPDATE:
Your operator+(const TSeries &) should look somewhat like this:
TSeries operator+(const TSeries & other)
{
if (this->_size != other._size)
{
std::cout << "Size doesn't match!" << std::endl;
return TSeries(); //Return empty object
}
TSeries tmp(*this); //Create copy
for (int i = 0; i < tmp._size; i++)
{
tmp._tab[i] += other._tab[i];
}
return tmp;
}
And your operator()(int, int) like this:
TSeries operator()(int position1, int position2)
{
if (position1 < 0) position1 = 0;
else if (position1 >= _size) position1 = _size - 1;
if (position2 < position1) position2 = position1;
else if (position2 >= _size) position2 = _size - 1;
return TSeries(_tab + position1, position2 - position1);
}
Maybe you want to throw exceptions in the error cases?