Unit 1: C++ Programming Basics and Functions - Practice Quiz

1 Which OOP concept combines data and the functions that operate on that data into a single unit?

2 Which of the following is commonly used as an object-oriented programming language?

3 Which C++ statement reads a value into the variable age?

4 Which C++ statement displays the word Hello?

5 Which keyword is used to define a class in C++?

6 Given class Student {};, which statement creates an object named s?

7 If age is a public member of object s, how is it accessed?

8 Which statement correctly describes a C++ union?

9 What is the main purpose of an enumeration in C++?

10 A member function defined inside its class definition is generally treated as what kind of function?

11 How many copies of a static data member are shared by all objects of a class?

12 What is the primary organizational unit in object-oriented programming?

13 Which operator is known as the stream insertion operator in C++?

14 What happens when an argument with a default value is omitted in a function call?

15 Which keyword requests that a function be expanded at the place where it is called?

16 What does the endl manipulator normally do?

17 What is function overloading in C++?

18 Which keyword allows a non-member function to access a class's private members?

19 What is a reference variable in C++?

20 In call by value, what does a function receive?

21 Consider the following C++ code:

class Shape { public: virtual void draw() { cout << "Shape"; } };

class Circle : public Shape { public: void draw() override { cout << "Circle"; } };

Shape* p = new Circle; p->draw();

Which OOP concept causes Circle to be printed?

22 The following code reads an integer correctly, but name becomes an empty string when the user enters 21 followed by Asha on the next line:

cin >> age;

getline(cin, name);

Which statement should normally be placed between these two statements?

23 What is printed by the following program fragment?

class Point {

int x;

public:

Point(int value) : x(value) {}

int getX() const { return x; }

};

Point p(6);

cout << p.getX();

24 Consider the following code:

class Box { public: int value; };

Box a; a.value = 5;

Box b = a;

b.value = 9;

cout << a.value << " " << b.value;

What is the output?

25 Given the following declarations, which statement is valid?

class Base { protected: int x = 4; };

class Derived : public Base { public: int read() { return x; } };

Derived d;

26 Which statement correctly compares C++ structures, unions, enumerations, and classes?

27 Given class Calc { public: int square(int); };, which definition is a non-inline member-function definition?

28 What is printed by this code?

class Widget {

public:

static int count;

Widget() { ++count; }

};

int Widget::count = 0;

Widget a, b;

Widget c = a;

cout << Widget::count;

29 A banking program must prevent arbitrary code from changing an account balance and must require all withdrawals to be validated. Which design best follows the object-oriented paradigm?

30 Consider the following code:

istringstream input("17abc");

int number;

char letter;

input >> number >> letter;

What values are stored if both extractions succeed?

31 Which function declaration uses default arguments legally in C++?

32 Which statement about an inline function in C++ is correct?

33 Assume the required formatting header is included. What does the following statement print?

cout << setfill('0') << setw(4) << 7 << " " << setw(2) << 5;

34 What is selected by d.show(3) in the following code?

class Base { public: void show(int) { cout << "Base"; } };

class Derived : public Base { public: void show(double) { cout << "Derived"; } };

Derived d;

d.show(3);

35 Why can reveal() access v.code in this code?

class Vault {

int code = 42;

friend int reveal(const Vault&);

};

int reveal(const Vault& v) { return v.code; }

36 What is the output of the following code?

int x = 4;

int& r = x;

r += 3;

int y = r;

++y;

cout << x << " " << r << " " << y;

37 A function must swap two caller variables and be invoked as swapValues(a, b). Which parameter declaration satisfies this requirement without returning the swapped values?

38 What does digitSum(5024) return?

int digitSum(int n) {

if (n == 0) return 0;

return n % 10 + digitSum(n / 10);

}

39 What is printed by the following recursive member-function call?

class Power {

int base;

public:

Power(int b) : base(b) {}

int calculate(int n) const {

if (n == 0) return 1;

return base * calculate(n - 1);

}

};

Power p(3); cout << p.calculate(4);

40 What happens when the following call is compiled?

void show(int);

void show(int, int = 0);

show(5);

41 Assume C++17. What does the following program print?

#include <iostream>

struct Base {
    virtual int value() const { return 1; }
};

struct Derived : Base {
    int value() const override { return 2; }
};

int byValue(Base object) { return object.value(); }
int byReference(const Base& object) { return object.value(); }

int main() {
    Derived d;
    std::cout << byValue(d) << ' ' << byReference(d);
}

42 What does this program print?

#include <iostream>
#include <sstream>
#include <limits>

int main() {
    std::istringstream in("12x 34");
    int a = -1, b = -1;

    in >> a >> b;
    in.clear();
    in.ignore(std::numeric_limits<std::streamsize>::max(), ' ');
    in >> b;

    std::cout << a << ' ' << b << ' ' << std::boolalpha << in.fail();
}

43 Why is the declaration Holder h; ill-formed?

class Holder {
    int& value;
public:
    Holder() = default;
};

Holder h;

44 Assume each constructor prints C followed by its identifier and each destructor prints D followed by its identifier. Which sequence is produced?

#include <iostream>

struct Trace {
    int id;
    Trace(int n) : id(n) { std::cout << 'C' << id << ' '; }
    ~Trace() { std::cout << 'D' << id << ' '; }
};

int main() {
    Trace a(1);
    {
        Trace b(2);
        static Trace c(3);
    }
    Trace d(4);
}

45 Which labeled expression is ill-formed because of the special protected-access rule?

class Base {
protected:
    int x = 1;
};

class Derived : public Base {
public:
    int inspect(Base& b, Derived& d) {
        int p = x;        // I
        int q = this->x;  // II
        int r = d.x;      // III
        int s = b.x;      // IV
        return p + q + r + s;
    }
};

46 Which statement correctly distinguishes C++ structures, unions, scoped enumerations, and classes?

47 A member function is defined inside a class definition placed in a header included by several translation units. Which statement is correct?

48 Assume C++17. What is printed?

#include <iostream>

class Counter {
    inline static int count = 0;
public:
    static void bump() { ++count; }
    static int value() { return count; }
};

int main() {
    Counter a, b;
    a.bump();
    b.bump();
    std::cout << a.value() << ' ' << Counter::value();
}

49 Consider a closed set of operations and an evolving set of shape types. Which comparison best describes the usual maintenance tradeoff between a procedural design using type-based dispatch and an object-oriented design using virtual methods?

50 Immediately after the extraction below, which stream-state description is normally correct?

std::istringstream in("10");
int value;
in >> value;

51 Assume all declarations occur in the same namespace scope. What is the result?

#include <iostream>

void total(int a, int b = 2);
void total(int a = 1, int b);
void total(int a, int b) { std::cout << a + b; }

int main() {
    total();
}

52 An external-linkage inline function is identically defined in multiple translation units and contains a function-local static variable. Which statement is required by the C++ language?

53 What does this program print?

#include <iostream>
#include <iomanip>

int main() {
    std::cout << std::hex
              << std::setfill('0')
              << std::setw(4) << 26
              << ' '
              << std::setw(2) << 10;
}

54 What does the first call print, and what does the second call print?

#include <iostream>

struct Base {
    void f(int) { std::cout << "Base"; }
};

struct Derived : Base {
    void f(double) { std::cout << "Derived"; }
};

int main() {
    Derived d;
    d.f(1);
    std::cout << ' ';

    struct Exposed : Derived {
        using Base::f;
    } e;
    e.f(1);
}

55 Consider this hidden friend definition:

class Number {
    int value;
public:
    explicit Number(int v) : value(v) {}
    friend Number operator+(Number a, Number b) {
        return Number(a.value + b.value);
    }
};

56 Which declaration creates a reference that can be safely read in the following statement?

57 What does this program print?

#include <iostream>

void modify(int value, int* address, int& reference) {
    value += 1;
    *address += 2;
    reference += 4;
}

int main() {
    int n = 1;
    modify(n, &n, n);
    std::cout << n;
}

58 Why does this recursive function fail to reach its base case for an initial argument greater than zero?

unsigned countdown(unsigned n) {
    if (n == 0)
        return 0;
    return countdown(n--);
}

59 Given the declarations below, which statement is correct?

class Vault {
    int code = 42;
    friend class Auditor;
};

class Auditor {
public:
    int read(const Vault& v) { return v.code; }
};

class SeniorAuditor : public Auditor {
public:
    int inspect(const Vault& v) { return v.code; }
};

60 A class declares void process(); in a header, and the function is defined outside the class in that same header without inline. The header is included by two translation units. What is the principal consequence?