Delete last element from dynamic array in C++

Question

I was making a std::vector like clone for a fun little project in C++, and I've come across the following problem: I'm trying to implement the method pop_back but for some reason, I can't get it to work. The class I'm using is called Array and is defined in ../d_arrays/d_array.h and ../d_arrays/d_array.cpp I have a main.cpp file in the root folder. Here is what I have so far:

RootDir/d_arrays/d_array.h

#include <iostream>

using namespace std;

class Array {

    public:

        Array(int len);

        void pop_back();
        void print();

    private:
        
        int* _array = NULL;
        int _len = 0;

};

RootDir/d_arrays/d_array.cpp

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

using namespace std;

Array::Array(int len) {
    _array = new int[len];
    _len = len;
}

void Array::pop_back() {
    _len--; // reduce length by 1

    int* tmp = new int[_len]; // create temp copy

    for (int i = 0; i < _len; i++) {
        tmp[i] = _array[i];
    }

    _array = tmp;
    delete[] tmp;
}

void Array::print() {
    for (int i = 0; i < _len; i++) {
        cout << _array[i] << " ";
    }
    cout << endl;
}

RootDir/main.cpp

#include <iostream>

#include "d_arrays/d_array.h"

using namespace std;

int main() {

    Array a = Array(10);

    cout << "Before: ";
    a.print();
    a.pop_back();
    cout << "After: ";
    a.print();

    return 0;

}

Im using g++ -o main main.cpp d_arrays/d_array.cpp to compile my code and ./main to run it.

whenever I run ./main I get the following output: Before: 0 0 0 0 0 0 0 0 0 0 After: 0 0 118968336 21854 0 0 0 0 0 What is happening here?