I am not able to print data from dynamic array - c++

Question

In this problem, I have to create a dynamic array and get data from the user, If the user keep entering value, a new array should be created and the data of the old array should be added to new array. and the old array should be deleted. I am not able to print the data from the new array. It is only printing garbage values. can you check where the problem is ?
#include<iostream>
using namespace std;
int main() {
int size = 5;
int* myarrptr = new int[size];
int* newarr = 0;
int count = 0;
int count2 = 0;
int i;
for (i = 0; i <= size; i++) {
if (i == size) {
count = *((myarrptr + i) - 1);
newarr = new int[size*2];
for (i = 0; i < size; i++) {
*(newarr + i) = *(myarrptr+i);
}
size = size + size;
delete[] myarrptr;
myarrptr = newarr;
*(myarrptr + i) = count;
}
cin >> *(myarrptr + i);
if (*(myarrptr+i) == -1) {
break;
}
count2++;
}
delete[] myarrptr;
cout << newarr[3];
}
Here is the code
I am trying to print the data from the newarr but I am getting garbage values.

Answer 1

This answer is not only for you but for other readers as well.
It looks like you are learning C++ from an outdated source, look at cppreference for examples. Get a recent C++ book or have a go at https://www.learncpp.com/ (that's pretty decent, and pretty up-to-date)
Example of what you want to do in current C++
#include <iostream>
#include <vector>
// output of a datatype in C++ is best generalized by overloading the output stream operator <<
// this will make it work with all kind of streams like std::cout, and std::ofstream (files)
std::ostream& operator<<(std::ostream& os, const std::vector<int>& values)
{
bool comma = false;
os << "[";
// range based for loop instead of index based
// this will never run outside the boundaries of your "array"
for (const int value : values)
{
if (comma) os << ", ";
os << value;
comma = true;
}
os << "]";
return os;
}
int main(int argv, char** argc)
{
std::size_t size;
std::cout << "Enter number of numbers : ";
std::cin >> size;
// for dynamically allocatable arrays use std::vector
// current C++ code should almost never need new/delete and raw pointers
std::vector<int> values(size); // your dynamic memory allocation happens here
// loop over all values by reference so you can modify them
for (int& value : values)
{
std::cout << "Enter a number : ";
std::cin >> value;
}
std::cout << values;
return 0;
}

Answer 2

There a solution already implemented in the standard template library in the vector header file. I would only use raw arrays in game development or constrained environments or to ethically hack. Look at the code I implemented for you. Also, I implemented a sentinel question to exit or continue because if you use a -1 as sentinel, you will not be able to add -1 as a value to display.
#include <iostream>
#include <vector>
int main() {
std::cout << "Enter values to display:" << std::endl;
bool shouldExit = false;
std::vector<int> values = std::vector<int>(0);
do {
std::cout << "Continue? (y/n): ";
char characterInput = '\0';
std::cin >> characterInput;
switch (characterInput) {
case 'y':
case 'Y':
break;
case 'n':
case 'N':
shouldExit = true;
break;
default:
std::cout << "Error: Enter valid input: \'y\' or \'n\' (case insensitive)" << std::endl;
continue;
}
std::cout << "Enter integer value: ";
int value = 0;
std::cin >> value;
values.push_back(value);
} while (!shouldExit);
if (values.size() == 0) {
std::cout << "No values to print" << std::endl;
}
else {
std::cout << "Values: " << std::endl;
for (unsigned int i = 0; i < values.size(); i++)
std::cout << "[" << i << "] = " << values[i] << std::endl;
}
}
If you need the raw array from a vector, you can always use the data() function.

Answer 3

your only printing the 4th value in the array with cout << newarr[3]; you'll need to add a for loop to print all the values