vector的实现出现的问题？？

求帮忙看下哪里出现了问题？？

#ifndef VECTOR_H
#define VECTOR_H

#include <iostream>
#include <memory>
#include <cstdlib>
#include <cstring>

//默认容量
const int default_capacity = 20;

template <class T>
class Vector
{
public:
  Vector() : m_capacity_(default_capacity), m_size_(0), m_ptr_(nullptr)
  {
  
  }

  Vector(int size, T data) : m_size_(size)
  {
    this->m_capacity_ = default_capacity + size;
    this->m_ptr_ = new T[this->m_capacity_];

    for (int i = 0; i < this->m_size_; ++i)
    {
      this->m_ptr_[i] = data;
    }
  }

  Vector(const Vector& v)
  {
    this->m_ptr_ = new T[v.m_size_];
    this->m_size_ = v.m_size_;
    this->m_capacity_ = default_capacity + v.m_capacity_;
    for (int i = 0; i < this->m_size_; ++i)
    {
      this->m_ptr_[i] = v.m_ptr_[i];
    }
  }

  ~Vector()
  {
    if (this->m_ptr_ != nullptr)
    {
      delete[] m_ptr_;
    }
    std::cout << "destory" << std::endl;
  }

  int size()
  {
    return this->m_size_;
  }

  T& operator[](int index)
  {
    return this->m_ptr_[index];
  }

  Vector& operator= (const Vector<T>& v)
  {
    if (this->m_ptr_ != nullptr)
    {
      delete[] this->m_ptr_;
      this->m_ptr_ = nullptr;
      this->m_capacity_ = 0;
      this->m_size_ = 0;
    }
    this->m_capacity_ = v.m_capacity_;
    this->m_size_ = v.m_size_;

    this->m_ptr_ = new T[this->m_capacity_];
    memcpy(this->m_ptr_, v.m_ptr_, this->m_size_ * sizeof(T));
    return *this;
  }

  void push_back(T data)
  {
    if (this->m_ptr_ == nullptr)
    {
      this->m_capacity_ = default_capacity;
      this->m_size_ = 0;
      this->m_ptr_ = new T[this->m_capacity_];
    }
    // 预留空间大小，当原容量小于要求大小时，才会重新分配
    if (this->m_size_ >= this->m_capacity_)
    {
      T* new_p = new T[this->m_capacity_ * 2];
      memcpy(new_p, this->m_ptr_, this->m_size_ * sizeof(T));
      this->m_capacity_ *= 2;
      delete[]this->m_ptr_;
      this->m_ptr_ = new_p;
    }
    this->m_ptr_[this->m_size_++] = data;
  }

  void pop_back()
  {
    if (this->m_size_ >= 1)
    {
      this->m_size_--;
    }
  }

private:
  int m_size_;
  int m_capacity_;
  T*  m_ptr_;

};



#endif // !VECTOR_H


```c++
#include "vector.h"

#include <iostream>

int main()
{
  Vector<int> p1;
  Vector<int> p2(3,1);
  Vector<int> p3(p1);
  Vector<int> p4 = p2;

  auto vector = p1;

  vector.push_back(1);
  //vector.push_back(2);

  for (int i = 0; i < vector.size(); i++)
  {
    std::cout << vector[i] << std::endl;
  }

  std::cout << p2.size() << std::endl;
  std::cout << vector.size() << std::endl;
  vector.pop_back();
  std::cout << vector.size() << std::endl;


}

```

代码没有问题 就是笔误，应该是这里拷贝构造函数申请内存大小的问题，和push_back时塞数据冲突了。
看下面的图就好，不好意思，很久不接触C++,顺路回顾了一下，过程中可能有错误的理解，你谨慎参考，参考下面
主要就是复制构造函数，以及重载=的逻辑，你实现没问题，笔误导致的问题。

T是对象，不是一段内存，不能memcpy
参考
《C++编程思想》 模板类 缺省构造 赋值构造 拷贝构造
《深度探索C++对象模型》虚表
《C++反汇编与逆向分析技术揭秘》