1In C++, which operator is used to access the memory address of a variable?
A.$.$
B.
C.
D.
Correct Answer:
Explanation:
The address-of operator returns the memory address of the operand.
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2What is the primary difference between malloc() in C and new in C++?
A.malloc() calls the constructor, new does not.
B.new calls the constructor, malloc() does not.
C.Neither calls the constructor.
D.Both call the constructor.
Correct Answer: new calls the constructor, malloc() does not.
Explanation:
new is an operator that allocates memory and initializes the object by calling its constructor, whereas malloc() is a library function that only allocates raw memory bytes.
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3In the context of Parameter Passing, what happens in Pass by Value?
A.A copy of the actual parameter's value is passed to the function.
B.The address of the actual parameter is passed to the function.
C.An alias to the actual parameter is created.
D.The function can directly modify the original variable.
Correct Answer: A copy of the actual parameter's value is passed to the function.
Explanation:
In Pass by Value, the value of the argument is copied into the formal parameter. Changes made to the parameter inside the function do not affect the original argument.
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4Which storage class in C/C++ preserves the value of a local variable between function calls?
A.static
B.extern
C.auto
D.register
Correct Answer: static
Explanation:
A static local variable is initialized only once and retains its value between function calls, as it is stored in the data segment rather than the stack.
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5Which concept in OOP allows a class to derive properties and behavior from another class?
A.Encapsulation
B.Abstraction
C.Inheritance
D.Polymorphism
Correct Answer: Inheritance
Explanation:
Inheritance is the mechanism where a new class (derived class) acquires the properties and methods of an existing class (base class).
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6In Java, objects are stored in which area of memory?
A.Heap
B.Stack
C.ROM
D.Register
Correct Answer: Heap
Explanation:
In Java, all objects are dynamically allocated on the Heap. The references to these objects may be stored on the Stack.
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7What is the result of dereferencing a NULL pointer in C++?
A.It returns 0.
B.It returns a random integer.
C.It creates a new object.
D.It causes a segmentation fault or undefined behavior.
Correct Answer: It causes a segmentation fault or undefined behavior.
Explanation:
Accessing memory at address 0 (NULL) is illegal in most operating systems, leading to a crash or undefined behavior.
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8Which of the following creates a Memory Leak?
A.Passing a pointer by reference.
B.Using a global variable.
C.Allocating memory on the heap and failing to free it.
D.Allocating memory on the stack.
Correct Answer: Allocating memory on the heap and failing to free it.
Explanation:
A memory leak occurs when dynamically allocated memory (Heap) is no longer needed but is not released back to the operating system.
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9What is Dynamic Binding (Late Binding)?
A.Linking a function call to the code to be executed at runtime.
B.Binding variable names to memory addresses during coding.
C.Linking a function call to the code to be executed at compile time.
D.Hardcoding function addresses.
Correct Answer: Linking a function call to the code to be executed at runtime.
Explanation:
Dynamic binding resolves function calls at runtime, typically used to implement polymorphism (e.g., Virtual Functions in C++).
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10In C++, what is the this pointer?
A.A pointer to the base class.
B.A pointer to the derived class.
C.A global pointer accessible by all classes.
D.A const pointer that points to the object invoking the member function.
Correct Answer: A const pointer that points to the object invoking the member function.
Explanation:
this is an implicit pointer passed to all non-static member functions, pointing to the object on which the function is called.
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11Which Java keyword is used to prevent a class from being inherited?
A.static
B.const
C.abstract
D.final
Correct Answer: final
Explanation:
In Java, declaring a class as final prevents it from being subclassed.
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12In C, if int arr[5] = {1, 2, 3, 4, 5}; and int *p = arr;, what is the value of *(p + 2)?
A.2
B.3
C.1
D.Address of 3
Correct Answer: 3
Explanation:
p points to arr[0]. p + 2 points to arr[2]. Dereferencing *(p + 2) gives the value at index 2, which is 3.
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13What is a Dangling Pointer?
A.A pointer that has not been initialized.
B.A pointer pointing to NULL.
C.A pointer pointing to a memory location that has been deleted or freed.
D.A pointer to a constant value.
Correct Answer: A pointer pointing to a memory location that has been deleted or freed.
Explanation:
If the memory a pointer points to is deallocated, but the pointer is not set to NULL, it becomes a dangling pointer, pointing to invalid memory.
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14Which feature of OOP describes wrapping data and methods into a single unit?
A.Polymorphism
B.Inheritance
C.Recursion
D.Encapsulation
Correct Answer: Encapsulation
Explanation:
Encapsulation is the bundling of data (variables) and methods (functions) that operate on that data into a single unit (class).
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15In Java, parameter passing is always:
A.Pass by Value
B.Pass by Pointer
C.Pass by Reference
D.Pass by Name
Correct Answer: Pass by Value
Explanation:
Java strictly uses Pass by Value. For objects, the 'value' passed is the reference (pointer/address) to the object, not the object itself, but the mechanism is still passing that reference by value.
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16What is the purpose of a Virtual Destructor in C++?
A.To allow multiple inheritance.
B.To prevent the class from being instantiated.
C.To delete objects faster.
D.To ensure the derived class destructor is called when deleting via a base class pointer.
Correct Answer: To ensure the derived class destructor is called when deleting via a base class pointer.
Explanation:
If a base class destructor is not virtual, deleting a derived object through a base pointer results in undefined behavior (usually only the base destructor runs), causing memory leaks.
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17Which area of memory is used for recursive function calls and local variables?
A.Stack
B.Heap
C.Data Segment
D.Code Segment
Correct Answer: Stack
Explanation:
The Stack is used for static memory allocation, including function call frames (activation records), local variables, and return addresses.
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18In C++, what is the size of an empty class?
A.2 bytes
B.4 bytes
C.0 bytes
D.1 byte
Correct Answer: 1 byte
Explanation:
The C++ standard ensures that an empty class has a size of at least 1 byte to ensure that two different objects will have different addresses.
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19What is the default access specifier for members of a class in C++?
A.public
B.internal
C.private
D.protected
Correct Answer: private
Explanation:
In C++, class members are private by default. In struct, they are public by default.
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20Which of the following correctly declares a pointer to a function accepting an integer and returning void in C++?
A.*void func(int);
B.void func(int *);
C.void *func(int);
D.void (*func)(int);
Correct Answer: void (*func)(int);
Explanation:
The syntax ReturnType (*PointerName)(ParameterTypes) creates a function pointer. Parentheses around *func are necessary to distinguish it from a function returning a pointer.
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21What implies the concept of Polymorphism?
A.Creating new classes from old ones.
B.Hiding data implementation.
C.Automatic memory management.
D.One interface, multiple methods.
Correct Answer: One interface, multiple methods.
Explanation:
Polymorphism allows objects to be treated as instances of their parent class, enabling a single interface (method call) to behave differently based on the actual object type.
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22What is the output of sizeof(char*) on a standard 64-bit architecture?
A.4
B.1
C.16
D.8
Correct Answer: 8
Explanation:
On a 64-bit architecture, memory addresses are 64 bits long, so a pointer (regardless of the data type it points to) occupies 8 bytes.
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23In Java, what mechanism handles the deallocation of memory on the Heap?
A.delete operator
B.free() function
C.Garbage Collector
D.Destructors
Correct Answer: Garbage Collector
Explanation:
Java uses automatic Garbage Collection to identify and free memory that is no longer reachable by the program, relieving the programmer of manual memory management.
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24What is a Reference in C++?
A.A pointer that can be null.
B.An alias for an existing variable.
C.A duplicate copy of a variable.
D.A variable stored in the CPU register.
Correct Answer: An alias for an existing variable.
Explanation:
A reference is essentially an alias or an alternative name for an existing variable. It must be initialized upon declaration and cannot be null.
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25Which problem arises when two pointers point to the same memory location and one is freed?
A.Buffer Underrun
B.Stack Overflow
C.Dangling Pointer
D.Memory Leak
Correct Answer: Dangling Pointer
Explanation:
When one pointer frees the memory, the second pointer still holds the address of that now-invalid memory, becoming a dangling pointer.
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26What is the Diamond Problem in C++?
A.An issue with pointer arithmetic on 2D arrays.
B.A syntax error in template classes.
C.A memory leak in a loop.
D.Ambiguity arising from multiple inheritance where two base classes inherit from a common ancestor.
Correct Answer: Ambiguity arising from multiple inheritance where two base classes inherit from a common ancestor.
Explanation:
The Diamond Problem occurs when a class inherits from two classes that both inherit from the same super-parent, potentially leading to two copies of the super-parent's members.
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27What is a Pure Virtual Function in C++?
A.A function that does not use any variables.
B.A function with no return type.
C.A virtual function initialized to 0, forcing derived classes to override it.
D.A function that cannot be overridden.
Correct Answer: A virtual function initialized to 0, forcing derived classes to override it.
Explanation:
Syntax: virtual void func() = 0;. This makes the class Abstract, and the function must be implemented by concrete derived classes.
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28In the context of parameter passing, what is an Activation Record?
A.A database of class methods.
B.A data structure stored on the stack containing local variables and return addresses for a function call.
C.A log of compilation errors.
D.A record of all heap allocations.
Correct Answer: A data structure stored on the stack containing local variables and return addresses for a function call.
Explanation:
Also known as a stack frame, the activation record holds the state of a specific function invocation.
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29Which of the following is true about Pass by Reference?
A.It passes a copy of the object.
B.It avoids copying large objects, improving performance.
C.It prevents the function from modifying the argument.
D.It requires more memory than pass by value.
Correct Answer: It avoids copying large objects, improving performance.
Explanation:
Pass by Reference passes the address/alias, avoiding the overhead of copying the entire object data, which is efficient for large structures/classes.
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30In C++, int &r = x; is an example of:
A.Address-of operator
B.Bitwise AND
C.Pointer declaration
D.Reference declaration
Correct Answer: Reference declaration
Explanation:
The & in a type declaration context (left side of assignment) signifies a reference variable.
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31What defines a Deep Copy?
A.Copying only the pointer address.
B.Copying the object bit-by-bit.
C.Copying the object and allocating new memory for the data pointed to by the object.
D.Using the assignment operator =.
Correct Answer: Copying the object and allocating new memory for the data pointed to by the object.
Explanation:
A deep copy duplicates the actual data pointed to by pointers within the object, ensuring the new object is fully independent of the original.
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32Which operator is used to release memory allocated by new[]?
A.remove
B.delete
C.free
D.delete[]
Correct Answer: delete[]
Explanation:
When allocating arrays with new[], you must use delete[] to ensure destructors are called for every element in the array.
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33Which of the following is NOT a principle of OOP?
A.Encapsulation
B.Compilation
C.Inheritance
D.Polymorphism
Correct Answer: Compilation
Explanation:
Compilation is a process of converting code to machine language, not a conceptual pillar of Object-Oriented Programming.
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34In Java, String objects are immutable. What does this mean?
A.They are stored in the stack only.
B.They cannot be deleted.
C.Their values cannot be changed after creation.
D.They cannot be passed to functions.
Correct Answer: Their values cannot be changed after creation.
Explanation:
Immutable means once a String object is created, its content cannot be altered. Operations that appear to modify it actually create a new String object.
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35What is the difference between struct and class in C++ regarding inheritance?
A.There is no difference.
B.Structs cannot inherit.
C.Classes cannot inherit from structs.
D.Structs inherit publicly by default; classes inherit privately by default.
Correct Answer: Structs inherit publicly by default; classes inherit privately by default.
Explanation:
The only technical differences are default access specifiers for members and default inheritance type (public for struct, private for class).
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36If a recursive function does not have a base case, what error occurs?
A.Stack Overflow
B.Heap Overflow
C.Linker Error
D.Compilation Error
Correct Answer: Stack Overflow
Explanation:
Infinite recursion fills up the stack with activation records until no space remains, causing a Stack Overflow.
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37What is Function Overloading?
A.Calling a function inside itself.
B.Defining multiple functions with the same name but different parameters.
C.Passing too many parameters to a function.
D.Defining a function in the base and derived class with the same signature.
Correct Answer: Defining multiple functions with the same name but different parameters.
Explanation:
Overloading allows multiple functions with the same name to exist if their parameter lists (types or number of arguments) differ.
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38In C++, the keyword friend allows a function to:
A.Access private and protected members of a class.
B.Become a member of the class.
C.Inherit from the class.
D.Delete the class object.
Correct Answer: Access private and protected members of a class.
Explanation:
A friend function is not a member of the class but is granted permission to access its non-public members.
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39Which segment of memory stores global and static variables?
A.Data Segment
B.Stack
C.Heap
D.Code Segment
Correct Answer: Data Segment
Explanation:
Global and static variables are stored in the Data Segment (initialized) or BSS (uninitialized) and exist for the lifetime of the program.
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40What is the outcome of void *p; in C++?
A.It declares a generic pointer that can hold the address of any data type.
B.It declares a null pointer.
C.It is a syntax error.
D.It declares a pointer that returns nothing.
Correct Answer: It declares a generic pointer that can hold the address of any data type.
Explanation:
A void pointer is a generic pointer. It cannot be dereferenced directly without casting because the compiler doesn't know the size of the data it points to.
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41Which of the following best describes an Abstract Class?
A.A class that is hidden from other files.
B.A class with only static methods.
C.A class that has no variables.
D.A class that cannot be instantiated and is meant to be subclassed.
Correct Answer: A class that cannot be instantiated and is meant to be subclassed.
Explanation:
Abstract classes serve as blueprints. In C++, they contain at least one pure virtual function. In Java, they are declared with the abstract keyword.
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42In C++, what is the syntax to access a member of a class using a pointer to an object?
A.
B.
C.
D..
Correct Answer:
Explanation:
The arrow operator () is used to access members of a structure or class via a pointer. ptr->member is equivalent to (*ptr).member.
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43What is RAII (Resource Acquisition Is Initialization) in C++?
A.A compiler optimization technique.
B.A programming idiom where resource management is tied to object lifetime.
C.A way to pass parameters.
D.A method to initialize arrays.
Correct Answer: A programming idiom where resource management is tied to object lifetime.
Explanation:
RAII ensures resources (like memory or file handles) are acquired in a constructor and released in the destructor, preventing leaks even if exceptions occur.
Method overriding relies on dynamic binding (runtime polymorphism) to determine which version of the method (base or derived) to execute based on the object's actual type.
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45In Java, does System.gc() force Garbage Collection immediately?
A.Yes, but only for the Stack.
B.No, it only suggests to the JVM that garbage collection is required.
C.Yes, always.
D.No, it creates a new memory segment.
Correct Answer: No, it only suggests to the JVM that garbage collection is required.
Explanation:
The JVM decides when to run the Garbage Collector. System.gc() is a request, not a command, and the JVM may ignore it.
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46What is the result of int *p = (int*)malloc(sizeof(int)); if memory allocation fails?
A.Terminates the program immediately.
B.Returns a dangling pointer.
C.Returns NULL.
D.Throws an exception.
Correct Answer: Returns NULL.
Explanation:
In C, malloc returns NULL if the system cannot allocate the requested memory block.
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47Which of the following is true about a Constructor?
A.It has the same name as the class and no return type.
B.It can be static.
C.It can be virtual.
D.It must have a return type of void.
Correct Answer: It has the same name as the class and no return type.
Explanation:
Constructors initializes objects. They cannot return values (not even void), cannot be virtual, and cannot be static.
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48How does passing a large object by value affect memory?
A.It saves memory.
B.It consumes more stack memory due to copying.
C.It has no effect on memory.
D.It allocates memory on the heap.
Correct Answer: It consumes more stack memory due to copying.
Explanation:
Pass by value creates a copy of the argument on the stack. For large objects, this copy operation consumes significant stack space and CPU time.
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49What is the primary role of the protected access specifier?
A.Accessible within the class and its derived classes.
B.Accessible everywhere.
C.Accessible only by friend functions.
D.Accessible only within the class.
Correct Answer: Accessible within the class and its derived classes.
Explanation:
protected members are similar to private members but are also accessible to classes that inherit from the base class.
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50Which pointer arithmetic operation is valid?
A.Adding two pointers.
B.Subtracting two pointers of the same type.
C.Multiplying a pointer by a constant.
D.Dividing a pointer by a constant.
Correct Answer: Subtracting two pointers of the same type.
Explanation:
Subtracting two pointers returns the number of elements (offset) between them. Adding, multiplying, or dividing pointers is invalid.