Unit 1: C++ programming exercises

cpp#include <iostream>
#include <iomanip>
using namespace std;
int main() {
    cout << left << setw(10) << "Item" << right << setw(8) << "Price" << '\n';
    cout << left << setw(10) << "Pen" << right << setw(8) << fixed << setprecision(2) << 12.5 << '\n';

    int n; cout << "Upto: "; cin >> n;
    for (int i = 2; i <= n; i++) {                         // primes
        bool p = true;
        for (int d = 2; d * d <= i; d++) if (i % d == 0) { p = false; break; }
        if (p) cout << i << ' ';
    }
    cout << "\nEven: "; for (int i = 2; i <= n; i += 2) cout << i << ' ';
    cout << "\nFibonacci: ";
    long a = 0, b = 1; for (int i = 0; i < n; i++) { cout << a << ' '; long t = a + b; a = b; b = t; }
}

cppint marks; cin >> marks;
if (marks >= 40) {
    if (marks >= 75) cout << "Distinction";
    else if (marks >= 60) cout << "First division";
    else cout << "Pass";
} else cout << "Fail";

int day; cin >> day;
switch (day) {
    case 1: cout << "Monday"; break;   case 2: cout << "Tuesday"; break;
    case 3: cout << "Wednesday"; break; case 4: cout << "Thursday"; break;
    case 5: cout << "Friday"; break;   case 6: cout << "Saturday"; break;
    case 7: cout << "Sunday"; break;   default: cout << "Invalid day";
}

long factIter(int n) { long f = 1; for (int i = 2; i <= n; i++) f *= i; return f; }
long factRec(int n)  { return n <= 1 ? 1 : n * factRec(n - 1); }

int a, b, c; cin >> a >> b >> c;
cout << "Largest " << max({a, b, c}) << " Smallest " << min({a, b, c});   // needs <algorithm>

cppint x = 25; int *p = &x;
cout << "Address " << p << " Content " << *p << '\n';

void swapRef(int &a, int &b) { int t = a; a = b; b = t; }   // call by reference
int m = 3, n = 7; swapRef(m, n);                             // m = 7, n = 3

bool isPalindrome(const string &s) {
    int i = 0, j = s.size() - 1;
    while (i < j) if (s[i++] != s[j--]) return false;
    return true;
}

cpp#include <cstring>
#include <algorithm>
char src[] = "Ludhiana", dest[20];
strcpy(dest, src);                                // copy C-string
string names[] = {"Riya", "Aman", "Kabir", "Simran"};
sort(names, names + 4);                           // alphabetical
int arr[] = {45, 12, 78, 3, 56};
for (int i = 0; i < 4; i++)                       // bubble sort
    for (int j = 0; j < 4 - i; j++)
        if (arr[j] > arr[j + 1]) swap(arr[j], arr[j + 1]);

cppclass Arith {
    double a, b;
public:
    Arith(double x, double y) : a(x), b(y) {}
    double add() { return a + b; }   double sub() { return a - b; }
    double mul() { return a * b; }   double div() { return b ? a / b : 0; }
};
Arith obj(12, 4);
Arith *ptr = &obj;
cout << ptr->add() << ' ' << ptr->mul() << ' ' << (*ptr).div();   // arrow and dot access

cppclass Student {
    static int count;
    int marks;
public:
    Student(int m) : marks(m) { ++count; }
    inline int getMarks() const { return marks; }
    static int total() { return count; }
    friend void compare(const Student &a, const Student &b);
};
int Student::count = 0;
void compare(const Student &a, const Student &b) {
    cout << (a.marks > b.marks ? "First" : "Second") << " is higher\n";
}

cppclass Box {
    int l, b;
public:
    Box() : l(1), b(1) { cout << "Default\n"; }
    Box(int x, int y) : l(x), b(y) { cout << "Parameterised\n"; }
    Box(const Box &o) : l(o.l), b(o.b) { cout << "Copy\n"; }
    ~Box() { cout << "Destructor\n"; }
    int area() { return l * b; }
};
int main() { Box a; Box b(3, 4); Box c = b; cout << c.area() << endl; }

• Viva: constructors have the class name and no return type; destructors run in reverse order of creation.

Overload area() for (base, height) using ½ × b × h and for three sides using Heron's formula, s = (a + b + c)/2 and area = √[s(s − a)(s − b)(s − c)].

cppclass Shape {                                    // abstract class
public:
    virtual double area() const = 0;             // pure virtual function
    virtual ~Shape() {}
};
class Circle : public Shape {
    double r;
public:
    Circle(double r) : r(r) {}
    double area() const override { return 3.14159 * r * r; }
};
class Rect : public Shape {
    double l, b;
public:
    Rect(double l, double b) : l(l), b(b) {}
    double area() const override { return l * b; }
};
Shape *s[] = { new Circle(2), new Rect(3, 4) };
for (Shape *x : s) { cout << x->area() << '\n'; delete x; }   // run-time polymorphism

• Publication → Book and Tape (hierarchical): the base stores title and price; each derived class adds its own data and a display function.
• Student → Exam → Result (multilevel): Student stores roll number, Exam stores marks and Result calculates and displays the total.

• Unary operator: overload - to negate the coordinates of a point: void operator-() { x = -x; y = -y; }
• Binary operator: overload + to add two complex numbers or two distances.
• Virtual function: a base Shape with virtual void area(); derived Circle and Rectangle override it; call through Shape *.
• Abstract class: make area() pure virtual (= 0) and show that Shape objects cannot be created.
• Files: write student records with ofstream, read them with ifstream, and copy a file with get() and put().

cpp#include <fstream>
#include <cctype>
int main() {
    ifstream in("input.txt");
    ofstream up("upper.txt"), cp("copy.txt");
    if (!in) { cerr << "Cannot open input.txt\n"; return 1; }
    char ch;
    while (in.get(ch)) {
        up.put(toupper(static_cast<unsigned char>(ch)));    // case conversion
        cp.put(ch);                                         // copy unchanged
    }
    cout << "Done\n";
}