OOPs PYQs practice

Author: Tamoziit

practice/p1.cpp

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+#include <iostream>
+using namespace std;
+
+void updateByReference(int &x)
+{
+ cout << &x << " : " << x << endl;
+ x += 10;
+}
+
+void updateByAddress(int *x)
+{
+ cout << x << " : " << *x << endl;
+ *x += 10;
+}
+
+int main()
+{
+ int a = 5;
+ updateByReference(a);
+ cout << "a after updateByReference: " << a << endl;
+ updateByAddress(&a);
+ cout << "a after updateByAddress: " << a << endl;
+ return 0;
+}

practice/p10.java

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+
+//package practice;
+import java.util.*;
+
+public class p10 {
+ void sort(int[] args) {
+ int i, j, temp;
+ for (i = 0; i < args.length - 1; i++) {
+ for (j = 0; j < args.length - i - 1; j++) {
+ if (args[j] > args[j + 1]) {
+ temp = args[j];
+ args[j] = args[j + 1];
+ args[j + 1] = temp;
+ }
+ }
+ }
+ }
+
+ void display(int[] args) {
+ int i;
+ for (i = 0; i < args.length; i++) {
+ System.out.print(args[i] + " ");
+ }
+ System.out.println();
+ }
+
+ public static void main(String[] args) {
+ p10 ob = new p10();
+ int i;
+ int[] arr = new int[5];
+ for (i = 0; i < 5; i++) {
+ arr[i] = Integer.valueOf(args[i]);
+ }
+
+ ob.display(arr);
+ ob.sort(arr);
+ System.out.println("Sorted args:");
+ ob.display(arr);
+ }
+}

practice/p11.cpp

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+#include <iostream>
+using namespace std;
+
+class Test
+{
+public:
+ int i;
+
+ Test(int idx)
+ {
+ i = idx;
+ cout << "Object Created: " << i << endl;
+ }
+
+ ~Test()
+ {
+ cout << "Object Destroyed: " << i << endl;
+ }
+};
+
+int main()
+{
+ Test t1(1);
+ Test t2(2);
+ return 0;
+}

practice/p12.java

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+class Department {
+ Department() {
+ System.out.println("CSE");
+ }
+
+ Department(String name) {
+ this();
+ System.out.println("CSE: String Constructor" + name);
+ }
+}
+
+public class p12 extends Department {
+ p12() {
+ System.out.println("Third year ");
+ }
+
+ p12(String name) {
+ this();
+ System.out.println("Third year: String Constructor" + name);
+ }
+
+ public static void main(String[] args) {
+ new p12("Section A+B+C");
+ }
+}

practice/p2.cpp

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+#include <iostream>
+using namespace std;
+
+void printVal(void *ptr)
+{
+ cout << "Value = " << *(int *)ptr << endl;
+}
+
+int main()
+{
+ int a = 7;
+ printVal((int *)&a);
+ return 0;
+}

practice/p3.cpp

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+#include <iostream>
+using namespace std;
+
+class test
+{
+public:
+ test() { cout << "Cons" << endl; }
+ ~test() { cout << "Dest" << endl; }
+};
+
+int main()
+{
+ for (int i = 0; i < 2; i++)
+ test obj;
+ return 0;
+}

practice/p4.cpp

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+#include <iostream>
+using namespace std;
+
+class MyClass
+{
+private:
+ static int count; // static variable to track number of objects
+
+public:
+ // Constructor
+ MyClass()
+ {
+ count++;
+ cout << "Object created. Total alive: " << count << endl;
+ }
+
+ // Destructor
+ ~MyClass()
+ {
+ count--;
+ cout << "Object destroyed. Total alive: " << count << endl;
+ }
+
+ // Static function to access count
+ static int getCount()
+ {
+ return count;
+ }
+};
+
+// Initialize static variable outside the class
+int MyClass::count = 0;
+
+int main()
+{
+ MyClass obj1;
+ {
+ MyClass obj2, obj3;
+ cout << "Currently alive: " << MyClass::getCount() << endl;
+ } // obj2 and obj3 go out of scope here
+
+ cout << "Currently alive after block: " << MyClass::getCount() << endl;
+
+ return 0;
+}

practice/p5.java

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+public class p5 {
+ public static void main(String[] args) {
+ int i;
+ System.out.println("Command Line Args:");
+ for (i = 0; i < args.length; i++) {
+ System.out.print(args[i] + " ");
+ }
+
+ System.out.println();
+ }
+}

practice/p6.java

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+//package practice;
+
+public class p6 {
+ double getArea(int r) {
+ return (22.0 / 7.0) * r * r;
+ }
+
+ double getArea(int l, int b) {
+ return l * b;
+ }
+
+ public static void main(String[] args) {
+ p6 ob = new p6();
+ System.out.println("Area of Circle = " + ob.getArea(7));
+ System.out.println("Area of Rectangle = " + ob.getArea(3, 4));
+ }
+}

practice/p7.cpp

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+#include <iostream>
+using namespace std;
+
+class Animal {
+public:
+ virtual void sound() { // virtual method
+ cout << "Animal makes a sound" << endl;
+ }
+};
+
+class Animal2 {
+public:
+ void sound() { // non-virtual method
+ cout << "Animal makes a sound in 2" << endl;
+ }
+};
+
+class Dog : public Animal {
+public:
+ void sound() override {
+ cout << "Dog barks" << endl;
+ }
+};
+
+class Dog2 : public Animal2 {
+public:
+ void sound() {
+ cout << "Dog barks 2" << endl;
+ }
+};
+
+int main() {
+ Animal* a;
+ Animal2* b;
+ Dog d;
+ Dog2 d2;
+ a = &d;
+ a->sound(); // Resolved at runtime
+ b = &d2;
+ b->sound();
+ return 0;
+}