Объяснить причины и способы устранения утечки памяти в деструкторе

#include "cow.h"
int main()
{
    Cow roman;
    roman.ShowCow();
    Cow natali("Natali Kobrii", "Shoping", 45);
    natali.ShowCow();
    Cow lili(natali);
    lili.ShowCow();
    //natali.~Cow();
    lili.ShowCow();
    Cow masa = lili;
    masa.ShowCow();
    return 0;

#ifndef COW_H_
#define COW_H_
class Cow
{
private:
    char name[20];
    char * hobby;
    double weight;
public:
    Cow();
    Cow(const char * nm, const char * ho, double wt);
    Cow(const Cow & c);
    ~Cow();
    Cow & operator=(const Cow & c);
    void ShowCow() const;
};
#endif

#include <iostream>
#include <cstring>
#include "cow.h"
Cow::Cow()
{
    std:strcpy(name, "no name");
    hobby = new char[std::strlen("no name") + 1];
    std::strcpy(hobby,"no name");
    weight = 0;
}
Cow::Cow(const char * nm, const char * ho, double wt)
{
    std::strcpy(name, nm);
    hobby = new char[strlen(ho) + 1];
    std::strcpy(hobby, ho);
    weight = wt;
}
Cow::Cow(const Cow & c)
{
    std::strcpy(name, c.name);
    hobby = new char[strlen(c.hobby) + 1];
    std::strcpy(hobby, c.hobby);
    weight = c.weight;
}
Cow::~Cow()
{
    delete [] hobby;
}
Cow & Cow::operator=(const Cow & c)
{
    if (this == &c)
        return *this;
    std::strcpy(name, c.name);
    delete[] hobby;
    hobby = new char[strlen(c.hobby) + 1];
    std::strcpy(hobby, c.hobby);
    weight = c.weight;
    return *this;
}
void Cow::ShowCow() const
{
    using namespace std;
    cout << "Name is : " << name << endl;
    cout << "Hobby is : " << hobby << endl;
    cout << "Weight is : " << weight << endl;
}