Past Exam Question Preparation

Question 1

What is overloading in C++?

Answer 1

Overloading in C++ is the ability to create multiple functions with the same name but different parameters. This allows functions to behave differently based on the input arguments.

void print(int i);
void print(double d);

Question 2

Example of overloading

Answer 2

void print(double d);
void print(const std::string& s);

Question 3

Provide an example illustrating the use of namespaces.

Answer 3

namespace First {
int value() { return 5; }
}

namespace Second {
int value() { return 10; }
}

int val = First::value(); // val is 5

Question 3

What is scope in C++ and what is the relevance of namespaces to scope?

Answer 3

Scope determines the visibility and lifetime of a variable or function. Namespaces are used to define a scope for identifiers to avoid name collisions, allowing the same name to be used in different contexts.

Question 4

What does the stream manipulator endl do?

Answer 4

endl is used to insert a newline character into the output stream and flush the stream.

Question 5

How are reference variables and pointers declared in C++? Give an example of each.

Answer 5

A reference variable is declared with an & symbol, a pointer with a *. Examples:

Question 5

Give an example using endl.

Answer 5

std::cout &laquo_space;“Hello” &laquo_space;std::endl; // Outputs “Hello” followed by a newline, and flushes the output stream.

Question 6

What role do assertions play in defensive programming?

Answer 6

Assertions are used to ensure that certain conditions hold true in a program. If an assertion fails, the program is terminated. This helps catch bugs by validating assumptions during development.

Question 6

Provide an example of using an assertion.

Answer 6

include <cassert></cassert>

int divide(int num, int denom) {
assert(denom != 0); // Program terminates if denom is 0
return num / denom;
}

Question 7

If a collection of type X contains X and Y objects, how are X and Y related?

Answer 7

X and Y are related by inheritance. Y is likely a subclass of X, meaning Y inherits from X. This allows a collection of type X to store objects of type Y.

Question 8

How do you declare an instance of a class Example with a member function void function(); and use it?

Answer 8

First, declare the instance of Example, then call the function() on it.
Example myInstance;
myInstance.function();

Question 8

How are the roles of constructors and destructors related to the lifetime of an object?

Answer 8

Constructors initialize an object when it is created, and destructors clean up before the object is destroyed. They manage resource allocation and deallocation, ensuring proper object lifecycle management.

Question 8

Provide an example to illustrate inheritance used in a collection.

Answer 8

class X {};
class Y : public X {};

std::vector<X*> collection;
collection.push_back(new X()); // X object
collection.push_back(new Y()); // Y object, which is a type of X

Question 9

Explain how we manage command line arguments to a program we have written.

Answer 9

Command line arguments are managed in the main function, which can accept two parameters: int argc (argument count) and char* argv[] (argument vector), representing the number of arguments and the arguments themselves.

Question 10

What does it mean for a class to be abstract, and how do we make a class abstract?

Answer 10

A class is abstract if it has at least one pure virtual function, which means it cannot be instantiated. We make a class abstract by declaring a pure virtual function using the syntax virtual ReturnType FunctionName() = 0;.

Question 11

Why might using getline(cin, input, ‘:’); to process data line by line be problematic?

Answer 11

Using getline with a delimiter like ‘:’ can be problematic if the delimiter appears within the data itself, leading to incorrect partitioning of the input.

Question 12

What is the role of a makefile?

Answer 12

A makefile automates the build process for software. It specifies how to compile and link the program, often defining build targets and dependencies.

Question 12

Describe two limitations of the C library rand function.

Answer 12

1. The rand() function often has a limited range and may not produce truly random numbers (predictable sequence).
2. Without srand(), rand() will produce the same sequence of numbers on each run.

Question 12

What is the purpose of using the protected access specifier?

Answer 12

The protected access specifier allows a class member to be accessible within its own class, friend classes, and subclasses, but not by other means.

Question 13

What is a header guard and why is it used?

Answer 13

A header guard prevents multiple inclusions of the same header file, which can lead to errors like redefinition. It’s usually implemented with #ifndef, #define, and #endif preprocessor directives.

Question 14

Provide an example code illustrating the use of a header guard.

Answer 14

ifndef MY_HEADER_H

#define MY_HEADER_H
// Header file contents
#endif // MY_HEADER_H

Question 14

How are namespaces related to scope?

Answer 14

Namespaces define a scope that allows for the organization of code and prevention of name conflicts

Question 15

What does the stream manipulator endl do?

Answer 15

endl inserts a newline character into the output stream and flushes the stream.

Question 16

How are reference variables declared in C++?

Answer 16

Reference variables are declared using the & symbol and must be initialized when declared.

Question 17

How are pointers declared in C++?

Answer 17

Pointers are declared using the * symbol and can be initialized to point to a specific memory address.

Question 18

What role do assertions play in defensive programming?

Answer 18

Assertions are used to validate assumptions made by the program and to catch bugs during development.

Question 19

How are X and Y related in a collection of type X?

Answer 19

In a collection type X that contains X and Y objects, Y must be a type that is derived from (inherits from) X or can be converted to type X.

Question 20

Explain polymorphism in a collection of type X containing Y objects.

Answer 20

Polymorphism allows objects of Y, a derived class of X, to be treated as objects of type X.

Question 21

How to create a reference

Answer 21

int a = 5;
int &b = a;

Question 22

What is a way to remember what a reference is

Answer 22

Think of b as an “alias” for a now.

Question 23

Explain with an example how function overloading works in C++. Create a function named print that is overloaded to handle both int and float types.

Answer 23

void print(int i) {
cout &laquo_space;“Integer: “ &laquo_space;i &laquo_space;endl;
}
void print(float f) {
cout &laquo_space;“Float: “ &laquo_space;f &laquo_space;endl;
}

Question 24

What is the byte size of Test test?

class Test {

static int i;
int j, t;

};

int Test::i;

int main(){

Test test;
cout << "Compute the size" << endl;
cout << sizeof(test) << endl;
return 0; }

Answer 24

It is 4 as static members dont count

Question 25

How to reverse a STRING

Answer 25

string reverseString(const string &str) {
string reversed = str;
int n = str.length();
for (int i = 0; i < n / 2; i++) {
swap(reversed[i], reversed[n - i - 1]);
}
return reversed;
}

Question 26

Function to calculate factorial (using recursion)

Answer 26

int factorial(int n) {
if (n <= 1) return 1;
return n * factorial(n - 1);
}
// DONT FORGET BASE CASE