OCCF (Orthodox Canonical Form) __ 정리없이 예시만 있음.

Canonical class form

• 생성자
• 소멸자
• 복사 생성자
• 대입 연산자 오버로딩

4 가지 멤버 함수가 있는 클래스 형태이다. 4가지가 필수는 아니다. 하지만 있으면 좋다고 한다. 왜 있어야 좋은지 차차 프로그램을 만들어보며 생각해보자.

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예시

• Sample.class.cpp

#include "Sample.class.hpp"
#include <iostream>

Sample::Sample(void) : _foo(0) {
  std::cout << "Sample created. Default." << std::endl;
}

Sample::~Sample(void) { std::cout << "Sample destroyed." << std::endl; }

Sample::Sample(int const n) : _foo(n) {
  std::cout << "Parametric Constructor called" << std::endl;
}

Sample::Sample(const Sample& src) {
  std::cout << "Copy constructor called." << std::endl;
  *this = src;
}

Sample& Sample::operator=(const Sample& rhs) {
  std::cout << "Assignment operator called" << std::endl;
  if (this != &rhs) {
    this->_foo = rhs.getFoo();
  }
  return *this;
}

std::ostream & operator<<(std::ostream &o, Sample const & i) {
  o << "The value of _foo is : " << i.getFoo();
  return o;
}

int Sample::getFoo(void) const { return this->_foo; }

• Sample.class.hpp

#ifndef SAMPLE_CLASS_HPP
# define SAMPLE_CLASS_HPP

# include <iostream>

class Sample {
 private:
  int _foo;

 public:
  Sample(void);  // Canonical form 생성자
  Sample(int const n);
  Sample(Sample const& src);  // Canonical form 복사 생성자
  ~Sample(void);              // Canonical form 소멸자

  Sample& operator=(Sample const& rhs);  // Canonical form 대입 연산자 오버로딩

  int getFoo(void) const;
};

std::ostream& operator<<(std::ostream& o, Sample const& i);

#endif

• main.cpp

#include <iostream>
#include "Sample.class.hpp"

int main(void) {
    Sample instance1;
    Sample instance2(42);
    Sample instance3(instance1);

    std::cout << instance1 << std::endl;
    std::cout << instance2 << std::endl;
    std::cout << instance3 << std::endl;

    instance3 = instance2;
    std::cout << instance3 << std::endl;

    return (0);
}