Garbage value when trying to remove value from dynamic array - c++

Question

i keep getting garbage value on one of the indexes in the dynamic array when i try to remove a value which was entered by user from a list of elements in the dynamic array.
used pointer as function parameters and replaced the value to be removed with 0 and by using a counter and for loop tried to skip all the 0s but in place of zero theres a garbage value.
#include<iostream>
#include<fstream>
using namespace std;
int size = 0;
int final = 0;
int* read(ifstream& a){
int temp;
a.open("data(1).txt");
while (!a.eof()){
a >> temp;
size++;
}
a.close();
a.open("data(1).txt");
int* arr = new int[size];
for (int i = 0; i < size; i++)
a >> arr[i];
return arr;
}
int* remove(int* a,int search){
for (int i = 0; i < size; i++){
if (a[i] == search)
a[i] = 0;
else final++;
}
int* change = new int[final+1];
for (int i = 0; i < size; i++){
if (a[i] > 0){
change[i] = a[i];
}
else continue;
}
delete[] a;
a = nullptr;
return change;
}
int main(){
int* ptr = nullptr;
int num;
cout << "please enter the number to remove: ";
cin >> num;
ifstream in;
ptr=read(in);
ptr=remove(ptr, num);
for (int i = 0; i < final; i++)
cout << ptr[i] << " ";
cout<<endl;
system("pause");
return 0;
}

Answer 1

There is much to discuss and critize about your code. Also your question is very unclear because we do not have your input file, nor do you tell us what the code should actually do. However, I will leave all "please write actual c++ rather than c without classes" aside and just point you to the one critical mistake:
This loop
int* change = new int[final+1];
for (int i = 0; i < size; i++){
if (a[i] > 0){
change[i] = a[i];
}
else continue;
}
And then this loop
for (int i = 0; i < final; i++)
cout << ptr[i] << " ";
It seems like you want to copy all elements that are >0 to change. Or maybe you want to copy all, its really hard to tell, because broken code is just broken, it does not explain itself. Anyhow...
The first loop leaves all elements change[i] where a[i] <= 0 uninitialized. The values at those indices i are indeterminate. There isn't really a value you can read. Attempting to read an indeterminate value results in undefined behavior.
You are attempting to read all elements of change, but some of them are not initialized, they are indeterminate values. Hence your code has undefined behavior.
There are other situations the will bring your code into bad states, like for example search not begin found in the input array or a[i] > 0 for some i > final. Though, I don't see a possiblity for any input to your code that would not eventually invoke undefined behavior.
You sould use a debugger to see where your code is doing something unexpected.