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--- cpp:object_creation [2019/04/19 08:34] – [Κύκλος ζωής των αντικειμένων - Δημιουργία και ανάθεση αντικειμένων στο heap] gthanos
+++ cpp:object_creation [2019/04/19 09:14] – [Παράδειγμα αρχικοποίησης δεικτών] gthanos
@@ Line 157: / Line 157: @@
   - πριν την ολοκλήρωση του προγράμματος είμαστε υποχρεωμένοι να ελευθερώσουμε τη μνήμη που δεσμεύτηκε στο //heap// κατά τη δημιουργία των αντικειμένων στα οποία δείχνουν οι δείκτες //r2, r3//
-<code cpp Rectangle.cpp>
+<code cpp Rectangle.hpp>
 #include <iostream>
 #include <cstdlib>
@@ Line 164: / Line 164: @@
 class Rectangle {
   private:
-    int *width, *height;
+    int *width_ptr, *height_ptr;
   public:
+    Rectangle();
     Rectangle(int w, int h);
+    Rectangle(int s);
     ~Rectangle();
     void setWidth(int w);
@@ Line 175: / Line 177: @@
 };
-Rectangle::Rectangle(int w, int h) {
+Rectangle::Rectangle() {
-  width = new (nothrow) int;
+  width_ptr = new (nothrow) int;
-  height = new (nothrow) int;
+  height_ptr = new (nothrow) int;
-  if(width == NULL || height == NULL) {
+  if(width_ptr == NULL || height_ptr == NULL) {
     cerr << "Memory allocation failure!\n";
     exit(-1);
   }
-  *width = w; *height = h;
+  *width_ptr = *height_ptr = 0;
-  cout << "Constructing rectangle (w:"<< *width <<", h:"<<*height<<")\n";
+  cout << "Calling 0 args constructor" << endl;
+}
+Rectangle::Rectangle(int w, int h) : Rectangle() {
+  *width_ptr = w;
+  *height_ptr = h;
+  cout << "Calling 2 args constructor" << endl;
+}
+Rectangle::Rectangle(int s) : Rectangle(s,s) {
+  cout << "Calling 1 args constructor" << endl;
 }
 Rectangle::~Rectangle() {
-  cout << "Destructing rectangle (w:"<< *width <<", h:"<<*height<<")\n";
+  cout << "Destructing rectangle (w:"<< *width_ptr <<", h:"<<*height_ptr<<")\n";
-  delete width;
+  delete width_ptr;
-  delete height;
+  delete height_ptr;
 }
-void Rectangle::setWidth(int w) { *width = w; }
+void Rectangle::setWidth(int w) { *width_ptr = w; }
-void Rectangle::setHeight(int h) { *height = h; }
+void Rectangle::setHeight(int h) { *height_ptr = h; }
-int Rectangle::getWidth() { return *width; }
+int Rectangle::getWidth() { return *width_ptr; }
-int Rectangle::getHeight() { return *height; }
+int Rectangle::getHeight() { return *height_ptr; }
-int Rectangle::getArea() { return *width * *height; }
+int Rectangle::getArea() { return *width_ptr * *height_ptr; }
 </code>
@@ Line 202: / Line 214: @@
 #include <iostream>
 using namespace std;
-#include "Rectangle.cpp"
+#include "Rectangle.hpp"
 int main() {
-  Rectangle rect {3, 4};
+  Rectangle rect {1, 2};
   Rectangle *r1, *r2, *r3;
   r1 = &rect;
-  r2 = new Rectangle {5, 6};
+  r2 = new Rectangle {2};
-  r3 = new Rectangle[2] { {4,8}, {7,3} };
+  r3 = new Rectangle[2] { {3,4}, {5} };
-  cout << "rect's getArea: " << rect.getArea() << endl;
-  cout << "*r1's getArea: " << r1->getArea() << endl;
+  cout << "---------------" << endl;
-  cout << "*r2's getArea: " << r2->getArea() << endl;
+  Rectangle **r4;
-  cout << "r3[0]'s getArea:" << r3[0].getArea() << endl;
+  r4 = new Rectangle*[2];
-  cout << "r3[1]'s getArea:" << r3[1].getArea() << endl;
+  r4[0] = new Rectangle {6};
+  r4[1] = new Rectangle (2,6);
+  cout << "---------------" << endl;
+  cout << "rect's  getArea: " << rect.getArea() << endl;
+  cout << "*r1's   getArea: " << r1->getArea() << endl;
+  cout << "*r2's   getArea: " << r2->getArea() << endl;
+  cout << "r3[0]'s getArea: " << r3[0].getArea() << endl;
+  cout << "r3[1]'s getArea: " << r3[1].getArea() << endl;
+  cout << "r4[0]'s getArea: " << r4[0]->getArea() << endl;
+  cout << "r4[1]'s getArea: " << r4[1]->getArea() << endl;
+  cout << "---------------" << endl;
   delete r2;
   delete[] r3;
+  cout << "---------------" << endl;
+  delete r4[0];
+  delete r4[1];
+  delete []r4;
   return 0;
 }