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//============================================================================
// Author : Sven Göthel
// Copyright : 2024 Göthel Software e.K.
// License : MIT
// Description : C++ Lesson 2.2 OOP (inheritance w/ virtual functions)
//============================================================================
#include <limits>
#include <string>
#include <memory>
#include <cassert>
#include <iostream>
class creature_t {
private:
int m_init_lifetime_left;
int m_lifetime_left;
protected:
/** Custom constructor (ctor) */
creature_t(int lifetime_left) noexcept
: m_init_lifetime_left(lifetime_left),
m_lifetime_left(lifetime_left) {}
/** Copy ctor */
creature_t(const creature_t& o) noexcept = default;
public:
/** Virtual destructor (dtor) */
virtual ~creature_t() noexcept = default;
int total_lifetime() const noexcept { return m_init_lifetime_left; }
int lifetime_left() const noexcept { return m_lifetime_left; }
int age() const noexcept { return total_lifetime() - lifetime_left(); }
bool alive() const noexcept { return lifetime_left() > 0; }
std::string lifesign() const noexcept { return alive() ? "☀" : "✝"; }
/** Subtract given years of life and return whether there is lifetime left */
bool tick(int years) noexcept {
if( m_lifetime_left > years ) {
m_lifetime_left -= years;
return true;
} else {
m_lifetime_left = 0;
return false;
}
}
/** Fully virtual to_string() method to be implemented in children classes */
virtual std::string to_string() const noexcept = 0;
protected:
std::string to_substring() const noexcept {
return "age "+std::to_string(age())+"/"+std::to_string(total_lifetime());
}
};
std::ostream& operator<<(std::ostream& out, const creature_t& v) {
return out << v.to_string();
}
class plant_t : public creature_t {
public:
/** Custom constructor (ctor) */
plant_t(int lifetime_left) noexcept
: creature_t(lifetime_left) {}
/** Copy ctor */
plant_t(const plant_t& o) noexcept = default;
/** Virtual to_string() override */
std::string to_string() const noexcept override { return "plant"+lifesign()+"["+creature_t::to_substring()+"]"; }
};
class animal_t : public creature_t {
public:
/** Custom constructor (ctor) */
animal_t(int lifetime_left) noexcept
: creature_t(lifetime_left) {}
/** Copy ctor */
animal_t(const creature_t& o) noexcept
: creature_t(o) { }
/** Virtual to_string() override */
std::string to_string() const noexcept override { return "animal"+lifesign()+"["+creature_t::to_substring()+"]"; }
};
int main(int, char*[]) {
plant_t p1(3);
animal_t a1(80);
std::cout << "00.p1 = " << p1 << std::endl;
std::cout << "00.a1 = " << a1 << std::endl;
creature_t& c1p1 = p1, &c2a1 = a1;
std::cout << "00.c1p1 = " << c1p1 << std::endl;
std::cout << "00.c2a1 = " << c2a1 << std::endl;
p1.tick(1);
a1.tick(1);
std::cout << "01.p1 = " << p1 << std::endl;
std::cout << "01.a1 = " << a1 << std::endl;
p1.tick(2);
a1.tick(79);
std::cout << "03.p1 = " << p1 << std::endl;
std::cout << "79.a1 = " << a1 << std::endl;
return 0;
}
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