[명품 C++ 프로그래밍] 03장 클래스와 객체 - 예제

Author: hellonayeon

명품 C++ 프로그래밍/03장/예제문제/3-1.cpp

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+#include <iostream>
+using namespace std;
+
+class Circle {
+public:
+    int radius;
+    double getArea();
+};
+
+double Circle::getArea() {
+    return 3.14*radius*radius;
+}
+
+int main()
+{
+    Circle donut; // 클래스 크기의 메모리가 할당
+    donut.radius = 1;
+    double area = donut.getArea();
+    cout << "donut의 면적은 " << area << endl;
+
+    Circle pizza;
+    pizza.radius = 30;
+    area = pizza.getArea();
+    cout << "pizza 면적은 " << area << endl;
+}

명품 C++ 프로그래밍/03장/예제문제/3-2.cpp

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+#include <iostream>
+using namespace std;
+
+class Rectangle {
+public:
+    int width;
+    int height;
+
+    int getArea();
+};
+
+int Rectangle::getArea() {
+    return width * height;
+}
+
+
+int main() {
+    Rectangle rect;
+    rect.width = 3;
+    rect.height = 5;
+    cout << "사각형의 면적은 " << rect.getArea() << endl;
+}

명품 C++ 프로그래밍/03장/예제문제/3-3.cpp

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+#include <iostream>
+using namespace std;
+
+class Circle {
+public:
+    int radius;
+    Circle();
+    Circle(int r);
+    double getArea();
+};
+
+Circle::Circle() {
+    radius = 1;
+    cout << "반지름 " << radius << " 원 생성" << endl;
+}
+
+Circle::Circle(int r) {
+    radius = r;
+    cout << "반지름 " << radius << " 원 생성" << endl;
+}
+
+double Circle::getArea() {
+    return 3.14*radius*radius;
+}
+
+int main() {
+    Circle donut;
+    double area = donut.getArea();
+    cout << "donut의 면적은 " << area << endl;
+
+    Circle pizza(30);
+    area = pizza.getArea();
+    cout << "pizza의 면적은 " << area << endl;
+}

명품 C++ 프로그래밍/03장/예제문제/3-4.cpp

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+#include <iostream>
+using namespace std;
+
+class Circle {
+public:
+    int radius;
+    Circle();
+    Circle(int r);
+    double getArea();
+};
+
+/* 위임 생성자 */
+Circle::Circle() : Circle(1) {  }
+
+/* 타겟 생성자 */
+Circle::Circle(int r) {
+    radius = r;
+    cout << "반지름 " << radius << " 원 생성" << endl;
+}
+
+double Circle::getArea() {
+    return 3.14*radius*radius;
+}
+
+int main() {
+    Circle donut;
+    double area = donut.getArea();
+    cout << "donut의 면적은 " << area << endl;
+
+    Circle pizza(30);
+    area = pizza.getArea();
+    cout << "pizza의 면적은 " << area << endl;
+}

명품 C++ 프로그래밍/03장/예제문제/3-5.cpp

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+#include <iostream>
+using namespace std;
+
+class Point {
+    int x, y;
+public:
+    Point();
+    Point(int a, int b);
+    void show() { cout << "(" << x << ", " << y << ")" << endl; }
+};
+
+Point::Point() : Point(0, 0) { }
+
+Point::Point(int a, int b) : x(a), y(b) { }
+
+int main() {
+    Point origin;
+    Point target(10, 20);
+    origin.show();
+    target.show();
+}

명품 C++ 프로그래밍/03장/예제문제/3-6.cpp

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+#include <iostream>
+using namespace std;
+
+class Rectangle {
+public:
+    int width, height;
+    Rectangle();
+    Rectangle(int w, int h);
+    Rectangle(int length);
+    bool isSquare();
+};
+
+Rectangle::Rectangle() : Rectangle(1, 1) { }
+
+Rectangle::Rectangle(int w, int h) {
+    width = w;  height = h;
+}
+
+Rectangle::Rectangle(int length) {
+    width = height = length;
+}
+
+bool Rectangle::isSquare() {
+    return width == height;
+}
+
+
+int main() {
+    Rectangle rect1;
+    Rectangle rect2(3, 5);
+    Rectangle rect3(3);
+
+    if (rect1.isSquare()) cout << "rect1은 정사각형이다." << endl;
+    if (rect2.isSquare()) cout << "rect2는 정사각형이다." << endl;
+    if (rect3.isSquare()) cout << "rect3은 정사각형이다." << endl;
+}