proga

#include "pch.h"
#include <iostream>
#include <cstring>
#include <string>
#include <fstream>
#pragma warning(disable : 4996)
using namespace std;

class vector {
public:
	int cap;
	int size;
	char* data;
	vector() {
		cap = 32;
		size = 0;
		data = new char[cap];
	}
	void push(char key[]) {
		if (cap == size || size>cap) {
			cap += strlen(key);
			char* temp = new char[cap];
			memcpy(temp, data, sizeof(char)*size);
			delete data;
			data = temp;
		}
		if (data[0] == '0') {
			strcpy(data, key);
			size += strlen(key);
		}
		strcat(data,key);
		size+=strlen(key);
	}
	void readfile() {
		char temp[32];
		ifstream fout("data.txt");
		fout >> temp;
		push(temp);
		fout.close();
	}
};
class User {
public:
	char name[32];
	char pass[32];
	bool sn = true;
	User() {
		strcpy(name, "Person");
		readfile();
	}
	static User* getinstance() {
		static User* p_instance = nullptr;
		if (!p_instance) {
			p_instance = new User();
		}
		return p_instance;
	}
	void changepass(char temp[]) {
		strcpy(pass, temp);
		recordfile();
	}
	static bool comparison(char word1[], char word2[]) {
		return strcmp(word1, word2);
	}
	static bool menucomp(char temp[]) {
		return strcmp(temp, "0");
	}
	void recordfile() {
		ofstream fin("data.txt");
		fin << pass;
		fin.close();
	}
	void readfile() {
		ifstream fout("data.txt");
		fout >> pass;
		fout.close();
	}
	~User() {
		delete getinstance();
	}
};

int main()
{
	User* obj = User::getinstance();
	vector vec;
	bool sign1 = true;

	if (obj->sn) {
		cout << "Create name: ";
		char temp[32];
		cin >> temp;
		strcpy(obj->name, temp);
		cout << "Create password: ";
		char temp2[32];
		cin >> temp2;
		strcpy(obj->pass, temp2);
		obj->recordfile();
	obj->sn = false;
	}
	while (sign1) {
		cout << "Press 0 to exit\nPassword can consist only numbers\n";
		cout << "User:" << obj->name << endl;
		cout << "Enter password: ";
		char temp[32] = " ";
		cin >> temp;
		vec.readfile();
		if (!User::menucomp(temp)) {
			return 0;
		}
		if (!User::comparison(vec.data, temp)) {
			cout << endl;
			cout << "Now you can change password" << endl;
			cout << "Press 0 to exit, 1 to change password\n";
			int n1 = 0;
			cin >> n1;
			bool sign2 = true;
			while (sign2) {
				switch (n1) {
				case 0: {
					sign2 = false;
					sign1 = false;
					break;
				}
				case 1: {
					cout << "Enter new password\n After you will press enter, programm will close\n";
					char temp2[32] = " ";
					cin >> temp2;
					obj->changepass(temp2);
					sign1 = false;
					sign2 = false;
					break;
				}
				default: {
					cout << "You entered wrong command" << endl;
				}
				}
			}
		}
		else {
			cout << "You entered wrong password" << endl;
		}
	}
	return 0;
}