//GSM.h

#pragma once
class GSM
{
private:
	unsigned long SKU;
	char *brand;
	char *model;
	float price;
	unsigned int count;
	bool dualSIM;

public:
	GSM();

	GSM(unsigned long SKU,
		const char *brand,
		const char *model,
		float price,
		unsigned int count,
		bool dualSIM);

	GSM(const GSM &m);

	unsigned long getSKU() const;
	void setSKU(unsigned long SKU);

	char *getBrand() const;
	void setBrand(const char *brand);

	char *getModel() const;
	void setModel(const char *model);

	float getPrice() const;
	void setPrice(float price);

	unsigned int getCount() const;
	void setCount(unsigned int count);

	bool getDualSIM() const;
	void setDualSIM(bool dualSIM);

	~GSM();

};
----------------------------------------------------------------------
//store.h

#pragma once
#include "GSM.h"
class Store
{
private:
	GSM **listGSM;
	size_t countGSM;
	size_t maxCountGSM;

	size_t IncrementCountGSM();

public:

	Store();
	size_t getCountGSM() const;
	size_t getMaxCountGSM() const;

	void addGSM(const GSM &m);
	bool deleteGSM(size_t index);
	bool changeGSM(const GSM &m, size_t index);
	void displayGSM() const;

	~Store();
};
--------------------------------------------------------------------------------
//GSM.cpp

#include "GSM.h"
#include <iostream>
#include <cstring>

GSM::GSM() :SKU(0), price(0), count(0), dualSIM(false), brand(NULL), model(NULL)
{
	setBrand("");
	setModel("");
}

GSM::GSM(unsigned long SKU,
	const char * brand,
	const char * model,
	float price,
	unsigned int count,
	bool dualSIM) : brand(NULL), model(NULL)
{
	setSKU(SKU);
	setBrand(brand);
	setModel(model);
	setPrice(price);
	setCount(count);
	setDualSIM(dualSIM);
}

GSM::GSM(const GSM & m) :
	GSM(m.SKU,
		m.brand,
		m.model,
		m.price,
		m.count,
		m.dualSIM)
{
}

unsigned long GSM::getSKU() const
{
	return SKU;
}

void GSM::setSKU(unsigned long SKU)
{
	this->SKU = SKU;
}

char * GSM::getBrand() const
{
	return brand;
}

void GSM::setBrand(const char * brand)
{
	if (this->brand) delete[] this->brand;
	size_t size = strlen(brand) + 1;
	this->brand = new char[size];
	strcpy_s(this->brand, size, brand);
}

char * GSM::getModel() const
{
	return model;
}

void GSM::setModel(const char * model)
{
	if (this->model)delete[] this->model;
	size_t size = strlen(model) + 1;
	this->model = new char[size];
	strcpy_s(this->model, size, model);
}

float GSM::getPrice() const
{
	return price;
}

void GSM::setPrice(float price)
{
	this->price = price;
}

unsigned int GSM::getCount() const
{
	return count;
}

void GSM::setCount(unsigned int count)
{
	this->count = count;
}

bool GSM::getDualSIM() const
{
	return dualSIM;
}

void GSM::setDualSIM(bool dualSIM)
{
	this->dualSIM = dualSIM;
}

GSM::~GSM()
{
	delete[] brand;
	delete[] model;
}
---------------------------------------------------------------------------
//store.cpp

#include "Store.h"
#include <iostream>

size_t Store::IncrementCountGSM()
{
	countGSM++;
	return getCountGSM();
}

Store::Store() : countGSM(0), maxCountGSM(4)
{
	listGSM = new GSM*[maxCountGSM];
}

size_t Store::getCountGSM() const
{
	return countGSM;
}

size_t Store::getMaxCountGSM() const
{
	return maxCountGSM;
}

void Store::addGSM(const GSM &m)
{
	if (getCountGSM() >= getMaxCountGSM())
	{
		maxCountGSM *= 2;
		GSM** newListGSM = new GSM*[getMaxCountGSM()];
		for (size_t i = 0; i < getCountGSM(); i++)
		{
			newListGSM[i] = listGSM[i];
		}
		delete[] listGSM;
		listGSM = newListGSM;
	}

	GSM* pGSM = new GSM(m);
	listGSM[getCountGSM()] = pGSM;
	IncrementCountGSM();
}

bool Store::deleteGSM(size_t index)
{
	if (index >= getCountGSM())return false;
	delete listGSM[index];
	countGSM--;
	for (size_t i = index; i < getCountGSM(); i++)
	{
		listGSM[i] = listGSM[i + 1];
	}
	return true;
}

bool Store::changeGSM(const GSM &m, size_t index)
{
	if (index >= getCountGSM())
	{
		return false;
	}
	delete listGSM[index];
	listGSM[index] = new GSM(m);
	return true;
}

void Store::displayGSM() const
{
	for (size_t i = 0; i < getCountGSM(); i++)
	{
		GSM* m = listGSM[i];
		std::cout << "GSM number: " << i << std::endl;
		std::cout << "  brand: " << m->getBrand() << ' ';
		std::cout << "quantity: " << m->getCount() << ' ';
		std::cout << "dualSIM: " << m->getDualSIM() << ' ';
		std::cout << "model: " << m->getModel() << ' ';
		std::cout << "price: " << m->getPrice() << ' ';
		std::cout << "SKU: " << m->getSKU() << std::endl;
	}
}

Store::~Store()
{
	for (size_t i = 0; i < getCountGSM(); i++)
	{
		delete listGSM[i];
	}
	delete[] listGSM;
}

---------------------------------------------------------------------------

//main.cpp

#include "Store.h"
#include "GSM.h"
#include <iostream>

int main()
{
	Store s;
	s.addGSM({ 123456, "Nokia", "3310", 50.50, 12, false });
	s.addGSM({ 234598, "iPhone", "8", 950.50, 50, true });
	s.addGSM({ 897608, "Samsung", "galaxy", 850.50, 15, false });
	s.addGSM({ 876343, "iPhone", "6 Plus", 430.50, 3, true });
	while (1)
	{
		char command;
		std::cin >> command;
		if (command == 'Q')
		{
			break;
		}
		switch (command)
		{
		case 'A':
		{
			std::cout << "You are add to change GSM. ";

			unsigned long SKU;
			std::cout << "SKU : ";
			std::cin >> SKU;
			char brand[64];
			std::cout << "brand : ";
			std::cin >> brand;
			char model[64];
			std::cout << "model : ";
			std::cin >> model;
			float price;
			std::cout << "price : ";
			std::cin >> price;
			unsigned int count;
			std::cout << "count : ";
			std::cin >> count;
			bool dualSIM;
			std::cout << "dualSIM(true/false) : ";
			std::cin >> dualSIM;

			GSM m(SKU, brand, model, price, count, dualSIM);
			s.addGSM(m);
			break;
		}
		case 'X':
		{
			std::cout << "You are about to remove GSM. ";

			size_t index;
			std::cin >> index;
			s.deleteGSM(index);

			break;
		}
		case 'C':
		{
			std::cout << "You are about to change GSM. ";

			unsigned long SKU;
			std::cout << "SKU : ";
			std::cin >> SKU;
			char brand[64];
			std::cout << "brand : ";
			std::cin >> brand;
			char model[64];
			std::cout << "model : ";
			std::cin >> model;
			float price;
			std::cout << "price : ";
			std::cin >> price;
			unsigned int count;
			std::cout << "count : ";
			std::cin >> count;
			bool dualSIM;
			std::cout << "dualSIM(true/false) : ";
			std::cin >> dualSIM;

			size_t index;
			std::cout << "index : ";
			std::cin >> index;

			GSM m(SKU, brand, model, price, count, dualSIM);
			s.changeGSM(m, index);
			break;
		}

		case 'D':
		{
			std::cout << "Printing all GSMs";

			s.displayGSM();
			break;
		}
		case ' ':
		case '\n':
			break;
		default:
			std::cout << "invalid command" << std::endl;
		}
	}

	int x;
	std::cin >> x;
}

---------------------------------------
end. имаш два хедъра - GSM и store и съответно същите .cpp файла, както и един мейн. Всичко работи