1What is the primary purpose of exception handling in C++?
A.To improve compilation speed
B.To allow syntax errors to pass
C.To handle run-time errors and abnormal conditions
D.To optimize memory usage
Correct Answer: To handle run-time errors and abnormal conditions
Explanation:
Exception handling provides a way to transfer control from one part of a program to another when a run-time error or an anomalous condition occurs.
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2Which keyword is used to raise an exception?
A.raises
B.try
C.catch
D.throw
Correct Answer: throw
Explanation:
The 'throw' keyword is used to signal (raise) an exception when an error occurs.
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3What happens during 'stack unwinding' in exception handling?
A.The program restarts from main()
B.Destructors of automatic objects are called as control leaves scopes
C.The stack memory is increased
D.Global variables are reset
Correct Answer: Destructors of automatic objects are called as control leaves scopes
Explanation:
When an exception is thrown, the runtime looks for a handler. As it exits scopes, it calls destructors for all fully constructed local objects. This is stack unwinding.
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4Which block contains the code that might generate an exception?
A.try
B.template
C.catch
D.throw
Correct Answer: try
Explanation:
The 'try' block encloses the code that is monitored for exceptions.
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5How do you define a catch block that handles all types of exceptions?
A.catch(void)
B.catch(all)
C.catch(Exception e)
D.catch(...)
Correct Answer: catch(...)
Explanation:
The syntax 'catch(...)' (ellipsis) is used to catch any type of exception that was thrown.
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6When using multiple catch blocks, how should they be ordered?
A.Random order
B.Specific to general
C.Alphabetical order
D.General to specific
Correct Answer: Specific to general
Explanation:
Catch blocks are checked sequentially. If a general catch (like a base class) comes first, it will shadow specific derived class catches. Therefore, specific types must come first.
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7What is the syntax to rethrow an exception currently being handled?
A.throw;
B.throw e;
C.return;
D.rethrow;
Correct Answer: throw;
Explanation:
Using 'throw;' without an operand inside a catch block rethrows the current exception to the next enclosing try/catch scope.
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8If an exception is thrown but not caught anywhere in the program, which function is called by default?
A.stop()
B.terminate()
C.abort()
D.exit()
Correct Answer: terminate()
Explanation:
If an exception is not caught, the C++ runtime calls std::terminate(), which usually calls abort().
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9Can a destructor throw an exception safely?
A.No, syntax error
B.No, it generally terminates the program if thrown during stack unwinding
C.Yes, always
D.Yes, but only integer exceptions
Correct Answer: No, it generally terminates the program if thrown during stack unwinding
Explanation:
Throwing exceptions from destructors is dangerous. If a destructor is called during stack unwinding and throws another exception, std::terminate() is called immediately.
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10Which header file is required for standard exception classes like std::exception?
A.<trycatch>
B.<exception>
C.<stdexcept>
D.<error>
Correct Answer: <exception>
Explanation:
The <exception> header defines the base class std::exception.
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11What is a C++ Template?
A.A blueprint for creating a family of classes or functions
B.A mechanism to hide data
C.A type of inheritance
D.A library of graphics
Correct Answer: A blueprint for creating a family of classes or functions
Explanation:
Templates allow writing generic code where the type is a parameter, acting as a blueprint for generating specific functions or classes.
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12Which keyword is used to declare a template?
A.type
B.template
C.typename
D.generic
Correct Answer: template
Explanation:
The 'template' keyword introduces a template declaration.
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13In the syntax template <typename T>, what does T represent?
A.A placeholder for a data type
B.The return type
C.A specific integer value
D.The class name
Correct Answer: A placeholder for a data type
Explanation:
T acts as a generic placeholder that gets replaced by a specific data type (like int, double, or a custom class) during instantiation.
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14Can keywords class and typename be used interchangeably in a template parameter list?
A.Yes, they are equivalent in this context
B.No, typename is deprecated
C.Yes, but class is preferred for functions
D.No, class is for classes and typename is for primitives
Correct Answer: Yes, they are equivalent in this context
Explanation:
In a template parameter declaration (e.g., template <class T> or template <typename T>), both keywords mean the same thing.
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15What is function template overloading?
A.Hiding a template function
B.Defining multiple templates with the same name but different parameters
C.Cannot overload templates
D.Calling a template function recursively
Correct Answer: Defining multiple templates with the same name but different parameters
Explanation:
Function templates can be overloaded by other templates or by non-template functions with the same name.
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16When a class template inherits from a non-template class, it is called:
A.Standard inheritance behavior
B.Mixed inheritance
C.Template inheritance
D.Invalid inheritance
Correct Answer: Standard inheritance behavior
Explanation:
A template class can inherit from a regular (non-template) class. The base class remains fixed, while the derived class is generic.
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17Which of the following is a valid Non-Type Template Parameter?
A.float value
B.string literal
C.dynamic object
D.int value
Correct Answer: int value
Explanation:
Non-type template parameters are restricted to integral types (int, char, long, etc.), pointers, or references. Floating-point numbers are generally not allowed (prior to C++20).
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18What is 'Template Specialization'?
A.Defining a specific implementation for a particular data type
B.Deleting a template
C.Creating a template inside another template
D.Using a template for integers only
Correct Answer: Defining a specific implementation for a particular data type
Explanation:
Specialization allows defining a distinct implementation of a template when a specific type (e.g., char*) is passed.
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19What happens at compile time when a template is instantiated?
A.The compiler generates the code for the specific type
B.The compiler creates a void pointer implementation
C.Nothing, it happens at runtime
D.The compiler ignores the template
Correct Answer: The compiler generates the code for the specific type
Explanation:
Templates rely on compile-time instantiation. The compiler generates a new version of the function/class for every unique type used.
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20Can a template class have static data members?
A.No
B.Yes, but they cannot be initialized
C.Yes, shared by all instances of all types
D.Yes, each instantiation has its own copy of the static member
Correct Answer: Yes, each instantiation has its own copy of the static member
Explanation:
Each instantiation (e.g., MyClass<int> and MyClass<double>) is a distinct type, so they have their own separate static members.
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21What does STL stand for?
A.System Template Library
B.Structured Template Language
C.Standard Type List
D.Standard Template Library
Correct Answer: Standard Template Library
Explanation:
STL stands for Standard Template Library, a set of C++ template classes to provide common programming data structures and functions.
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22What are the three main components of STL?
A.Containers, Algorithms, Iterators
B.Classes, Objects, Methods
C.Files, Streams, Buffers
D.Inputs, Processes, Outputs
Correct Answer: Containers, Algorithms, Iterators
Explanation:
The core components of STL are Containers (data storage), Algorithms (procedures to process data), and Iterators (connectors).
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23Which component acts as a bridge between containers and algorithms?
A.Allocator
B.Functor
C.Adapter
D.Iterator
Correct Answer: Iterator
Explanation:
Iterators provide a uniform way to traverse containers, allowing algorithms to process data without knowing the internal details of the container.
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24Which of the following is a Sequence Container?
A.stack
B.map
C.vector
D.set
Correct Answer: vector
Explanation:
Sequence containers store elements in a linear order. Vector, list, and deque are sequence containers. Map and set are associative.
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25Which header file is needed to use generic algorithms like sort()?
A.<stl>
B.<vector>
C.<algorithm>
D.<algo>
Correct Answer: <algorithm>
Explanation:
The standard header <algorithm> contains the definitions for algorithmic functions like sort, search, count, etc.
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26What is the underlying data structure of a std::vector?
A.Hash Table
B.Doubly Linked List
C.Linked List
D.Dynamic Array
Correct Answer: Dynamic Array
Explanation:
A vector is a dynamic array that can resize itself automatically when elements are added or removed.
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27What is the underlying data structure of a std::list?
A.Doubly Linked List
B.Binary Tree
C.Dynamic Array
D.Stack
Correct Answer: Doubly Linked List
Explanation:
std::list is implemented as a doubly linked list, allowing fast insertion and deletion at any point.
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28Which iterator type does std::vector support?
A.Input Iterator only
B.Random Access Iterator
C.Bidirectional Iterator
D.Forward Iterator
Correct Answer: Random Access Iterator
Explanation:
Vectors support random access iterators, meaning you can jump to any element instantly using arithmetic (e.g., it + 5).
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29What is the time complexity for random access in a std::list?
A.O(n*n)
B.O(n)
C.O(1)
D.O(log n)
Correct Answer: O(n)
Explanation:
Lists are linked lists. To access the Nth element, you must iterate through the links from the start, taking linear time O(n).
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30Which function adds an element to the end of a vector?
A.insert()
B.push_back()
C.enqueue()
D.add()
Correct Answer: push_back()
Explanation:
The push_back() function appends an element to the end of a vector.
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31Which function removes the last element of a vector?
A.extract()
B.remove_last()
C.delete()
D.pop_back()
Correct Answer: pop_back()
Explanation:
The pop_back() function removes the last element of the container.
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32Which of the following operations is faster in std::list compared to std::vector?
A.Sorting
B.Memory usage
C.Random access
D.Insertion in the middle
Correct Answer: Insertion in the middle
Explanation:
Insertion in a list only involves changing pointers (O(1) once the position is found), whereas vector insertion requires shifting elements (O(n)).
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33What does the begin() function return?
A.An iterator to the first element
B.The first value
C.An iterator to the last element
D.A pointer to the memory
Correct Answer: An iterator to the first element
Explanation:
begin() returns an iterator pointing to the first element of the container.
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34What does the end() function return?
A.The last element
B.NULL
C.An iterator to the position just past the last element
D.An iterator to the last element
Correct Answer: An iterator to the position just past the last element
Explanation:
end() returns an iterator referring to the 'past-the-end' element, which acts as a placeholder and does not point to valid data.
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35How do you access the element at index 3 in a vector v safely with bounds checking?
A.v.get(3)
B.v[3]
C.*(v+3)
D.v.at(3)
Correct Answer: v.at(3)
Explanation:
The at() function performs bounds checking and throws an out_of_range exception if the index is invalid. The [] operator does not check bounds.
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36What happens to the capacity of a vector when it gets full?
A.It automatically increases, typically doubling its size
B.It throws an exception
C.It deletes old elements
D.It stops accepting elements
Correct Answer: It automatically increases, typically doubling its size
Explanation:
Vectors manage memory dynamically. When capacity is reached, they allocate a larger block of memory (often 2x) and copy elements over.
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37Which header file is required to use std::vector?
A.<vec>
B.<array>
C.<vector>
D.<list>
Correct Answer: <vector>
Explanation:
The standard header is <vector>.
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38Can std::vector store elements of different data types?
A.Yes, it is loosely typed
B.Yes, using void pointers
C.Only if defined as vector<var>
D.No, it is a homogeneous container
Correct Answer: No, it is a homogeneous container
Explanation:
STL containers are homogeneous; they store elements of a single specific type defined at declaration.
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39Which operator is used to dereference an iterator to get the value it points to?
A.*
B.::
C.->
D.&
Correct Answer: *
Explanation:
The asterisk (*) operator is used to dereference an iterator, just like a pointer, to access the value.
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40In std::list, what type of iterator is provided?
A.Forward only
B.Bidirectional
C.None
D.Random Access
Correct Answer: Bidirectional
Explanation:
Lists provide bidirectional iterators, allowing traversal forward and backward, but not random jumps.
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41What is the result of v.size() on an empty vector v?
A.Exception
B.1
C.0
D.Garbage value
Correct Answer: 0
Explanation:
size() returns the number of elements currently in the container. For an empty vector, it is 0.
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42What is the difference between size() and capacity() in a vector?
A.Size is in bytes, capacity is in elements
B.They are the same
C.Size is used memory, capacity is allocated memory
D.Capacity is used memory, size is allocated memory
Correct Answer: Size is used memory, capacity is allocated memory
Explanation:
Size is the number of actual elements. Capacity is the amount of memory allocated before the vector needs to resize.
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43How do you check if a container v is empty?
A.v.size() == null
B.v.checkEmpty()
C.v.null()
D.v.empty()
Correct Answer: v.empty()
Explanation:
The empty() function returns a boolean: true if size is 0, false otherwise.
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44Which function clears all elements from a vector?
A.clear()
B.erase()
C.delete()
D.remove()
Correct Answer: clear()
Explanation:
The clear() function removes all elements from the container, leaving its size at 0.
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45In a template, what is 'Class Template Inheritance'?
A.Copying code manually
B.Creating a class inside a function
C.Inheritance is not allowed in templates
D.Deriving a class template from a template or non-template base class
Correct Answer: Deriving a class template from a template or non-template base class
Explanation:
Class templates can take part in inheritance relationships just like regular classes.
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46What keyword allows an iterator to move to the next element?
A.next()
B.move()
C.>> (Shift operator)
D.++ (Increment operator)
Correct Answer: ++ (Increment operator)
Explanation:
Iterators overload the increment (++) operator to traverse to the next element in the container.
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47Does std::list support the [] operator?
A.Only if the list is sorted
B.Yes
C.No
D.Only for read access
Correct Answer: No
Explanation:
std::list does not support random access via subscript operator [] because it is a linked list.
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48In exception handling, which logic applies to derived/base class catches?
A.Base class catch must appear before Derived class catch
B.They cannot exist in the same try-catch block
C.Order does not matter
D.Derived class catch must appear before Base class catch
Correct Answer: Derived class catch must appear before Base class catch
Explanation:
Because a Derived object 'is-a' Base object, catching Base first would catch Derived exceptions too, making the Derived catch unreachable.
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49Which method inserts elements into a vector at a specific position?
A.push()
B.put()
C.insert()
D.add()
Correct Answer: insert()
Explanation:
The insert(iterator, value) function places an element at the specified iterator position, shifting subsequent elements.
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50What is the return type of the bad_alloc exception?
A.It is a type thrown, usually when new fails
B.Memory failure
C.NULL
D.void
Correct Answer: It is a type thrown, usually when new fails
Explanation:
std::bad_alloc is the exception type thrown by the new operator when memory allocation fails. It doesn't 'return' a type in the function sense.