[C++]생성자(Constructor)

[[연습문제 1]]

#include <iostream>
using std::cout;
using std::endl;
using std::cin;

class T
{
public:
 T();
 T(int n);
 T(int a1,double a2, char b);
 T(char a);
 T(char *p);
 T(int a1, int a2, char *p);
};

int main()
{
    T ob, ob2, ob3;   //객체 생성
    T ob4(100);       //객체 생성 시 인수전달
    T ob5(10, 20.34, 'B');
    T ob6('a');
    T ob7;
    T ob8("Hello");
    T ob9(50, 60, "Happy Birthday");
    return 0;
}

T::T()
{
 cout << "생성자\n";
}

T::T(int n)
{
 cout << n << "을 받는 생성자\n";
}

T::T(int a1, double a2, char b)
{
 cout << a1<< ", " << a2<< ", " << b << "를 받는 생성자\n";
}

T::T(char *p)
{
 cout << p << "를 받는 생성자\n";
}

T::T(int a1, int a2, char *p)
{
 cout << a1<< ", " << a2<< ", " << p << "를 받는 생성자\n";
}

T::T(char a)
{
 cout << a << "를 받는 생성자\n";
}

[[연습문제 2]]

#include <iostream>
#include <string.h>
using std::cout;
using std::cin;
using std::endl;

class ACC
{
private:
 int accId;              //계좌번호
    char pw[5];             //비밀번호
    char name[20];          //이름
    int bal;                //잔액
 
public:     
 ACC(int accid, char *Pp, char *Pn, int bal);
    void deposit();         //입금
    void withdraw();        //출금
    void showData();        //잔액조회
};     

///////////////////////////////////////////main 
int main()
{
    ACC ac(1111, "1234", "김수현", 5000); //객체 생성 후, 초기화
 
    ac.showData();  //잔액조회
    ac.deposit();   //입금
    ac.withdraw();  //출금
    ac.showData();  //잔액조회
    
    return 0;
}

///////////////////////////////////////////ACC 멤버함수 외부정의 
ACC::ACC(int accid, char *Pp, char *Pn, int bal2)
{
 accId = accid;
 strcpy(pw, Pp);
 strcpy(name, Pn);
 bal = bal2;
}
void ACC::deposit()
{
    int m;
    
    cout << "\n입금금액 입력 : ";
    cin >> m;
    
    bal += m;
    
    cout << "\t\t" << m << "원 입금완료~!!\n";
}

void ACC::withdraw()
{
    int m;
    
    cout << "\n출금금액 입력 : ";
    cin >> m;
    
    bal -= m;
    
    cout << "\t\t" << m << "원 출금완료~!!\n";
}

void ACC::showData()
{
    cout << "\n계좌번호 : " << accId << endl;
    cout << name << "회원님의 잔액은 " << bal << "입니다.\n";
}

[[연습문제 3]]

>>Triangle.h<<

class Triangle
{
private:
 int base, height;
public:
 Triangle(int b, int h);
 double GetArea();
};

>>main.cpp<<

#include <iostream>
#include "Triangle.h"
using std::cin; using std::cout; using std::endl;

int main()
{
 int base, height;
 cout << "\n *** 삼각형 넓이 구하기 ***\n\n";
 cout << "밑변 : "; 
 cin >> base;
 cout << "높이 : ";
 cin >> height;

 Triangle tri(base, height);
 cout << "삼각형의 넓이는 " << tri.GetArea() << "입니다\n";
 return 0;
}

>>Triangle.cpp<<

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

Triangle::Triangle(int b, int h) : base(b), height(h)
{}
double Triangle::GetArea()
{
 return (base*height)/2.0;
}