Latest C++ Functions MCQs

Q: 1. What is a function in C++?

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Q: 2. Which keyword is used to return a value from a function?

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Q: 3. What happens if a C++ function does not specify a return type?

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Q: 4. What is a function prototype?

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Q: 5. From which function does the execution of a C++ program begin?

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Q: 6. What does a void return type signify?

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Q: 7. What are formal parameters in a function?

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Q: 8. What are actual parameters?

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Q: 9. Which of the following is true about pass-by-value?

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Q: 10. How do you pass a variable by reference in C++?

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1. What is a function in C++?

a) A block of code that performs a specific task

b) A keyword to define variables

c) A memory allocation tool

d) A data type

Correct Answer: a) A block of code that performs a specific task

Explanation:

A function is a reusable block of code designed to perform a specific task.

2. Which keyword is used to return a value from a function?

a) yield

b) return

c) give

d) send

Correct Answer: b) return

Explanation:

The return keyword is used to exit a function and send a value back to the caller.

3. What happens if a C++ function does not specify a return type?

a) It defaults to void

b) It defaults to int

c) It causes a compilation error

d) It returns a null pointer

Correct Answer: c) It causes a compilation error

Explanation:

Standard C++ requires every function to have an explicitly declared return type.

4. What is a function prototype?

a) The actual body of the function

b) A declaration specifying its name, return type, and parameters

c) A built-in system function

d) A template parameter

Correct Answer: b) A declaration specifying its name, return type, and parameters

Explanation:

A function prototype tells the compiler about the function's signature before its actual definition.

5. From which function does the execution of a C++ program begin?

a) start()

b) main()

c) init()

d) execute()

Correct Answer: b) main()

Explanation:

Every standard C++ program must have a main() function, which serves as the entry point.

6. What does a void return type signify?

a) The function returns an integer 0

b) The function does not return any value

c) The function accepts no parameters

d) The function is a template

Correct Answer: b) The function does not return any value

Explanation:

The void keyword indicates that the function performs an action but yields no output value.

7. What are formal parameters in a function?

a) Variables declared inside the function's parameter list

b) Values passed during the function call

c) Variables declared globally

d) Variables returned by the function

Correct Answer: a) Variables declared inside the function's parameter list

Explanation:

Formal parameters act as local placeholders for the values passed to the function when called.

8. What are actual parameters?

a) Variables declared in the function definition

b) The real values passed to a function when it is called

c) Global variables

d) Return values

Correct Answer: b) The real values passed to a function when it is called

Explanation:

Actual parameters are the real values or variables supplied during a function call.

9. Which of the following is true about pass-by-value?

a) Modifying the parameter affects the original argument

b) A copy of the actual argument is passed to the function

c) It passes the memory address

d) It is faster for large objects

Correct Answer: b) A copy of the actual argument is passed to the function

Explanation:

In pass-by-value, the function works on a separate copy, so original variables are unaffected.

10. How do you pass a variable by reference in C++?

a) Using the * operator

b) Using the & operator

c) Using the @ operator

d) Using the ref keyword

Correct Answer: b) Using the & operator

Explanation:

The ampersand symbol in the parameter list designates it as a reference, allowing direct modification.

11. What happens when an array is passed to a function?

a) The entire array is copied by value

b) A pointer to its first element is passed

c) The size is automatically known

d) It causes an error

Correct Answer: b) A pointer to its first element is passed

Explanation:

Arrays decay into pointers when passed to functions, transferring the address of the first element.

12. What is a default argument?

a) A value assigned by the compiler automatically

b) A value assigned to a parameter to be used if no argument is provided

c) An argument that cannot be changed

d) An argument passed by reference

Correct Answer: b) A value assigned to a parameter to be used if no argument is provided

Explanation:

Default arguments allow a function to be called with fewer parameters than declared.

13. What is the rule for assigning default arguments?

a) They must be assigned from right to left

b) They must be assigned from left to right

c) They must be assigned randomly

d) Only the first argument can be default

Correct Answer: a) They must be assigned from right to left

Explanation:

Once a parameter has a default value, all subsequent parameters to its right must also have default values.

14. What does a const parameter indicate?

a) The parameter is passed by reference

b) The parameter value cannot be modified inside the function

c) The function returns a constant

d) The function is thread-safe

Correct Answer: b) The parameter value cannot be modified inside the function

Explanation:

Using const ensures that the function treats the parameter as read-only.

15. What is function overloading?

a) Defining multiple functions with the same name but different parameters

b) Calling a function multiple times

c) Using a function in a loop

d) Returning multiple values

Correct Answer: a) Defining multiple functions with the same name but different parameters

Explanation:

Function overloading allows functions sharing a name to coexist, provided their parameter lists differ.

16. Can two functions be overloaded solely by changing their return types?

a) Yes

b) No

c) Only if one returns void

d) Only for class members

Correct Answer: b) No

Explanation:

The C++ compiler determines the function to call based on arguments. It cannot differentiate based solely on return type.

17. What is name mangling in C++?

a) Encrypting code

b) Modifying function names internally to include parameter types for overloading

c) Changing variable names dynamically

d) A debugging technique

Correct Answer: b) Modifying function names internally to include parameter types for overloading

Explanation:

To support overloading, the compiler alters internal function names by appending parameter type information.

18. What is the purpose of the extern C block?

a) To include C source code

b) To prevent name mangling for C compatibility

c) To convert C++ code to C

d) To define external variables

Correct Answer: b) To prevent name mangling for C compatibility

Explanation:

extern C instructs the compiler not to mangle names, allowing proper linking with C libraries.

19. What is an inline function?

a) A function that executes automatically

b) A request to the compiler to insert the function body at the place of its call

c) A function with no parameters

d) A function that returns void

Correct Answer: b) A request to the compiler to insert the function body at the place of its call

Explanation:

Inline functions suggest embedding code directly to avoid function call overhead.

20. Which scenario makes the compiler most likely to ignore an inline request?

a) The function contains just one statement

b) The function has recursive calls

c) The function returns void

d) The function takes no arguments

Correct Answer: b) The function has recursive calls

Explanation:

Complexities like recursion or large loops typically cause the compiler to treat inline requests as normal functions.

21. Can the main() function in standard C++ be overloaded?

a) Yes

b) No

c) Only with void return types

d) Only in namespaces

Correct Answer: b) No

Explanation:

Standard C++ rules explicitly forbid overloading the main() function.

22. What are the common parameters of the main() function?

a) void argc, void argv

b) int argc, char argv

c) char argc, int argv

d) string argc[]

Correct Answer: b) int argc, char argv

Explanation:

The standard parameters for main are int argc (argument count) and char argv (argument vector).

23. What does argc represent in main()?

a) The array of arguments

b) The name of the program

c) The number of command-line arguments passed

d) The exit code

Correct Answer: c) The number of command-line arguments passed

Explanation:

argc stands for argument count, indicating how many strings are in the argv array.

24. What is recursion?

a) A loop that never terminates

b) A function calling itself directly or indirectly

c) A function returning multiple values

d) A function calling main()

Correct Answer: b) A function calling itself directly or indirectly

Explanation:

Recursion occurs when a function involves a call to itself to solve smaller instances of a problem.

25. What is essential for a recursive function to prevent an infinite loop?

a) A base condition

b) A global variable

c) A switch statement

d) A void return type

Correct Answer: a) A base condition

Explanation:

A base case or terminating condition stops recursive calls, preventing stack overflow.

26. What happens if a recursive function does not have a base case?

a) It runs exactly once

b) It causes a stack overflow at runtime

c) It causes a compilation error

d) It defaults to zero

Correct Answer: b) It causes a stack overflow at runtime

Explanation:

Without a base case, recursion continues infinitely until the program consumes all available stack memory.

27. What is tail recursion?

a) When the recursive call is the last operation in the function

b) When recursion is done at the beginning

c) When a function calls two different functions

d) When recursion only happens in if-statements

Correct Answer: a) When the recursive call is the last operation in the function

Explanation:

Tail recursion occurs when the recursive call is the absolute final action, allowing memory optimization.

28. Which of the following describes mutual recursion?

a) A function calling itself twice

b) Two or more functions calling each other cyclically

c) A function returning a reference to itself

d) A recursive function with multiple base cases

Correct Answer: b) Two or more functions calling each other cyclically

Explanation:

Mutual recursion happens when function A calls function B, and function B calls function A.

29. Is it legal for a standard C++ function to return a C-style array directly?

a) Yes

b) No

c) Only if it is an integer array

d) Only if it returns void

Correct Answer: b) No

Explanation:

Raw arrays cannot be returned directly. You must return a pointer, struct, or container like std::vector.

30. What is the danger of returning a reference to a local variable?

a) It creates a dangling reference because the variable is destroyed on exit

b) It causes a syntax error

c) It makes the variable global

d) There is no danger

Correct Answer: a) It creates a dangling reference because the variable is destroyed on exit

Explanation:

Local variables are destroyed when scope ends. Returning a reference points to invalid memory.

31. Which keyword makes a free-standing function visible only within its translation unit?

a) private

b) static

c) extern

d) internal

Correct Answer: b) static

Explanation:

Applying static to a free function gives it internal linkage, making it invisible outside its source file.

32. How are function arguments pushed onto the call stack typically in cdecl?

a) Left to right

b) Right to left

c) Middle first

d) Simultaneously

Correct Answer: b) Right to left

Explanation:

While parameter evaluation order is unspecified in C++, traditional calling conventions like cdecl push right to left.

33. What is a function pointer?

a) A pointer to the return value

b) A variable that stores the memory address of a function

c) A function returning a pointer

d) A smart pointer

Correct Answer: b) A variable that stores the memory address of a function

Explanation:

A function pointer holds the memory address of executable code, allowing dynamic calls.

34. What is the correct syntax for a pointer to a function returning void and taking no arguments?

a) void *ptr();

b) void (*ptr)();

c) void ptr*();

d) void (&ptr)();

Correct Answer: b) void (*ptr)();

Explanation:

The parentheses around *ptr indicate it is a pointer to a function, not a function returning a pointer.

35. What is a callback function?

a) A function that calls main()

b) A function passed as an argument to another function to be executed later

c) A recursive function

d) An exception handler

Correct Answer: b) A function passed as an argument to another function to be executed later

Explanation:

A callback is executable code passed as an argument to be invoked at a specific time.

36. In C++11, what represents generic callable objects including function pointers and lambdas?

a) std::invoke

b) std::callable

c) std::function

d) std::ptr

Correct Answer: c) std::function

Explanation:

std::function is a polymorphic wrapper that can store, copy, and invoke any callable target.

37. What is a functor in C++?

a) A function taking no arguments

b) An object of a class that overloads the function call operator ()

c) A function pointer alias

d) A built-in mathematical function

Correct Answer: b) An object of a class that overloads the function call operator ()

Explanation:

A functor acts like a function because its class defines operator(), allowing internal state maintenance.

38. What is a lambda expression in C++?

a) A macro definition

b) An anonymous, inline function object

c) A generic template

d) A global variable

Correct Answer: b) An anonymous, inline function object

Explanation:

Lambdas are convenient inline anonymous functions that can capture variables from their scope.

39. What do the square brackets [] represent in a lambda expression?

a) Parameter list

b) Return type

c) Capture clause

d) Execution block

Correct Answer: c) Capture clause

Explanation:

The capture clause [] defines which variables from the surrounding scope are accessible inside the lambda.

40. What does a capture clause of [&] signify in a lambda?

a) Capture all variables by value

b) Capture all variables by reference

c) Capture no variables

d) Capture only pointers

Correct Answer: b) Capture all variables by reference

Explanation:

[&] captures all local variables by reference, allowing the lambda to modify them.

41. What does a capture clause of [=] signify in a lambda?

a) Capture all variables by value

b) Capture all variables by reference

c) Assign new values

d) Compare variables

Correct Answer: a) Capture all variables by value

Explanation:

[=] captures all local variables used within the lambda by making a read-only copy.

42. By default, variables captured by value in a lambda are:

a) Mutable

b) Volatile

c) Const

d) Static

Correct Answer: c) Const

Explanation:

Variables captured by value are implicitly read-only unless the mutable keyword is specified.

43. Which keyword makes variables captured by value modifiable inside a lambda?

a) dynamic

b) mutable

c) changeable

d) volatile

Correct Answer: b) mutable

Explanation:

The mutable keyword removes the implicit const qualification from variables captured by value.

44. How do you specify the return type of a lambda explicitly?

a) Inside the capture clause

b) Using a trailing return type with ->

c) Before the parameter list

d) Inside the parameter list

Correct Answer: b) Using a trailing return type with ->

Explanation:

Lambdas use trailing return types, e.g., [](https://www.google.com/search?q=) -> int { return 5; }.

45. What is a generic lambda (introduced in C++14)?

a) A lambda using auto in its parameter list

b) A lambda without a capture clause

c) A lambda called from C

d) A lambda that captures globals

Correct Answer: a) A lambda using auto in its parameter list

Explanation:

C++14 allows using auto for lambda parameters, making the lambda a template function object.

46. Which keyword marks a function to explicitly not throw any exceptions?

a) nothrow

b) noexcept

c) safe

d) throw()

Correct Answer: b) noexcept

Explanation:

The noexcept specifier indicates that the function is guaranteed not to throw exceptions.

47. What does a constexpr function guarantee?

a) It can be evaluated at compile time given constant expressions

b) It never takes parameters

c) It runs in O(1) time

d) It cannot have a return value

Correct Answer: a) It can be evaluated at compile time given constant expressions

Explanation:

constexpr indicates the return value can be computed at compile-time if inputs are compile-time constants.

48. What is the difference between constexpr and consteval (C++20)?

a) They are the same

b) consteval forces strict compile-time evaluation, constexpr allows runtime too

c) constexpr is strictly for compile time

d) consteval is for variables only

Correct Answer: b) consteval forces strict compile-time evaluation, constexpr allows runtime too

Explanation:

A consteval function MUST produce a compile-time constant, whereas constexpr can run at runtime if needed.

49. What does the = delete syntax do to a function?

a) Deletes the function from memory

b) Explicitly forbids its use, causing a compile error if called

c) Marks it deprecated

d) Frees its variables

Correct Answer: b) Explicitly forbids its use, causing a compile error if called

Explanation:

Defining a function as = delete intentionally prevents its usage to stop unwanted conversions or copies.

50. What is a variadic function in C++?

a) A function that has a variable memory footprint

b) A function that can accept a variable number of arguments

c) A function that changes its return type dynamically

d) A function without parameters

Correct Answer: b) A function that can accept a variable number of arguments

Explanation:

Variadic functions can accept an indefinite number of arguments.

51. Which header is required for using old C-style variadic functions like va_list?

a) <variadic.h>

b) <stdarg.h> or

c)

d)

Correct Answer: b) <stdarg.h> or

Explanation:

The header defines macros needed to handle C-style variadic arguments.

52. What is a function template?

a) A blueprint for creating functions that can operate on different data types

b) A function that only accepts string parameters

c) A design pattern

d) A function returning a void pointer

Correct Answer: a) A blueprint for creating functions that can operate on different data types

Explanation:

Templates allow creating generic functions that work with any data type, avoiding code duplication.

53. What keyword is used to declare a function template?

a) generic

b) template

c) auto

d) typename

Correct Answer: b) template

Explanation:

The template keyword is required before the template parameter list.

54. What is template argument deduction?

a) When the compiler automatically determines the data type of the template parameter

b) When the compiler removes unused templates

c) When the programmer explicitly forces a type

d) When the program casts a variable

Correct Answer: a) When the compiler automatically determines the data type of the template parameter

Explanation:

C++ compilers can often deduce the type parameter from the arguments provided during the call.

55. What is template specialization?

a) Making a template run faster

b) Providing a specific implementation of a template for a particular data type

c) Restricting templates to classes

d) Defining multiple parameters

Correct Answer: b) Providing a specific implementation of a template for a particular data type

Explanation:

Specialization allows overriding the generic template code with a specific implementation for a certain type.

56. What is a friend function in C++?

a) A function imported from another project

b) A non-member function with access to private and protected members of a class

c) A function with no return type

d) A static function

Correct Answer: b) A non-member function with access to private and protected members of a class

Explanation:

Declaring a function as a friend gives it full access to the class's private data.

57. Does a friend function have a 'this' pointer?

a) Yes, always

b) No, because it is not a member of the class

c) Only if passed explicitly

d) Only when called statically

Correct Answer: b) No, because it is not a member of the class

Explanation:

Since friend functions are not class members, they lack an implicit 'this' pointer.

58. Where can a friend function be declared inside a class?

a) Only in the private section

b) Only in the public section

c) Anywhere; access specifiers do not affect friend declarations

d) Only in the protected section

Correct Answer: c) Anywhere; access specifiers do not affect friend declarations

Explanation:

The location of a friend declaration does not change its meaning or access level.

59. What is a member function?

a) A function defined inside a namespace

b) A function declared within a class definition

c) A function returning an object

d) A function accepting class objects

Correct Answer: b) A function declared within a class definition

Explanation:

Member functions are associated with a class and operate on the objects of that class.

60. How is a class member function defined outside the class?

a) Using the dot (.) operator

b) Using the scope resolution operator (::)

c) Using the arrow (->) operator

d) Using the colon (:) operator

Correct Answer: b) Using the scope resolution operator (::)

Explanation:

The :: operator is used to define a function outside the class, specifying which class it belongs to.

61. What is the 'this' pointer in C++?

a) A pointer to the next instruction

b) An implicit pointer that holds the address of the current object

c) A pointer to the global scope

d) A pointer to the base class

Correct Answer: b) An implicit pointer that holds the address of the current object

Explanation:

Inside non-static member functions, 'this' is a hidden pointer to the object calling the function.

62. What is a static member function?

a) A function that can only be called once

b) A member function that belongs to the class itself, not to any specific object

c) A function that cannot change local variables

d) An inline function

Correct Answer: b) A member function that belongs to the class itself, not to any specific object

Explanation:

Static member functions are class-level functions and can be called without instantiating an object.

63. Which of the following is true about static member functions?

a) They can access non-static class members directly

b) They have a 'this' pointer

c) They can only access static data members and other static member functions

d) They must be virtual

Correct Answer: c) They can only access static data members and other static member functions

Explanation:

Because they lack a 'this' pointer, static functions can only interact with static class data.

64. What does a const keyword at the end of a member function declaration mean?

a) The function returns a constant value

b) The function cannot modify any non-static data members of the class

c) The function takes constant parameters

d) The function is static

Correct Answer: b) The function cannot modify any non-static data members of the class

Explanation:

A const member function promises not to alter the state of the object it is called on.

65. What is a virtual function?

a) A function with no body

b) A member function expected to be redefined in derived classes for dynamic polymorphism

c) A function executed in a virtual machine

d) A friend function

Correct Answer: b) A member function expected to be redefined in derived classes for dynamic polymorphism

Explanation:

Virtual functions allow C++ to support runtime polymorphism through base class pointers.

66. What is a pure virtual function?

a) A virtual function without a return type

b) A virtual function assigned the value of 0, forcing derived classes to implement it

c) A function returning 0

d) A function marked pure

Correct Answer: b) A virtual function assigned the value of 0, forcing derived classes to implement it

Explanation:

Declaring a function as = 0 makes it pure virtual, turning its class into an abstract base class.

67. What happens if a class has at least one pure virtual function?

a) It becomes a sealed class

b) It becomes an abstract class and objects of it cannot be created

c) It causes a compilation error

d) It becomes a struct

Correct Answer: b) It becomes an abstract class and objects of it cannot be created

Explanation:

Abstract classes serve as interfaces. Because the function is undefined, instantiation is prohibited.

68. Can constructors be virtual functions?

a) Yes

b) No

c) Only in abstract classes

d) Only default constructors

Correct Answer: b) No

Explanation:

Constructors cannot be virtual because the virtual table mechanism relies on the object being constructed first.

69. Can destructors be virtual functions?

a) Yes, and it is highly recommended when using inheritance

b) No, it causes undefined behavior

c) Only if the constructor is virtual

d) Yes, but they must be pure virtual

Correct Answer: a) Yes, and it is highly recommended when using inheritance

Explanation:

Virtual destructors ensure that when a derived object is deleted via a base pointer, the derived destructor is invoked.

70. What does the override keyword do in C++11?

a) Allows overriding private functions

b) Explicitly states that a function is intended to override a virtual function in a base class

c) Overloads a function dynamically

d) Stops a function from being overridden

Correct Answer: b) Explicitly states that a function is intended to override a virtual function in a base class

Explanation:

The override specifier helps prevent bugs by making the compiler check if a corresponding virtual function exists.

71. What does the final keyword do when applied to a member function?

a) Makes the function return a constant value

b) Prevents any further overriding of this virtual function in derived classes

c) Terminates the program after execution

d) Optimizes the function for speed

Correct Answer: b) Prevents any further overriding of this virtual function in derived classes

Explanation:

Marking a virtual function as final restricts derived classes from providing their own implementation.

72. What is the C++14 auto return type deduction?

a) The compiler guesses the function name

b) The compiler automatically figures out the return type based on the return statement

c) The function returns an auto pointer

d) The function doesn't need to return anything

Correct Answer: b) The compiler automatically figures out the return type based on the return statement

Explanation:

Using auto as a return type lets the compiler deduce the type from the expression in the return statement.

73. If a function with an auto return type has multiple return statements, what must be true?

a) Only the first one matters

b) They must all deduce to the exact same type

c) It automatically returns a variant

d) It causes a runtime error

Correct Answer: b) They must all deduce to the exact same type

Explanation:

For return type deduction to work, all return paths within the function must evaluate to the same data type.

74. What does the [[nodiscard]] attribute do?

a) Prevents returning memory addresses

b) Generates a compiler warning if the return value of the function is ignored by the caller

c) Prevents discarding the function from optimization

d) Removes the function from the global namespace

Correct Answer: b) Generates a compiler warning if the return value of the function is ignored by the caller

Explanation:

[[nodiscard]] is used to enforce that the caller handles the return value, like checking an error code.

75. What is the use of the [[deprecated]] attribute on a function?

a) It deletes the function from the binary

b) It warns developers that the function is outdated and its use is discouraged

c) It makes the function run slower

d) It changes the access specifier to private

Correct Answer: b) It warns developers that the function is outdated and its use is discouraged

Explanation:

The compiler will issue a warning if a function marked as [[deprecated]] is called.

76. What is a trailing return type syntax?

a) auto func() -> int;

b) int -> func();

c) func() : int;

d) func auto -> int;

Correct Answer: a) auto func() -> int;

Explanation:

Trailing return types place the return type after the parameter list following an arrow.

77. In the context of exceptions, what happens if a function marked noexcept throws an exception?

a) The exception is caught automatically

b) The program calls std::terminate and crashes immediately

c) The exception is ignored

d) It causes a memory leak

Correct Answer: b) The program calls std::terminate and crashes immediately

Explanation:

If an exception escapes a function marked noexcept, the C++ runtime forcefully terminates the application.

78. Can a function be overloaded based strictly on whether a parameter is passed by value or passed by reference?

a) Yes

b) No, it causes an ambiguity error when calling the function

c) Only if they are template functions

d) Yes, but only in classes

Correct Answer: b) No, it causes an ambiguity error when calling the function

Explanation:

The compiler cannot determine whether to copy the variable or pass its reference, leading to ambiguity.

79. What is the difference between void func(const int x) and void func(int x) in declarations?

a) They overload each other successfully

b) They are treated as exactly the same signature by the compiler at the declaration level

c) One is faster than the other

d) The first one is illegal

Correct Answer: b) They are treated as exactly the same signature by the compiler at the declaration level

Explanation:

Top-level const qualifiers on pass-by-value parameters are ignored in function signatures.

80. What does a function returning an rvalue reference look like?

a) int func();

b) int& func();

c) int&& func();

d) int* func();

Correct Answer: c) int&& func();

Explanation:

The double ampersand (&&) denotes an rvalue reference, often used in move semantics.

81. How do you pass a multidimensional array to a function?

a) void func(int arr[][]);

b) void func(int arr[][10]);

c) void func(int** arr);

d) Multidimensional arrays cannot be passed

Correct Answer: b) void func(int arr[][10]);

Explanation:

When passing multidimensional C-style arrays, all dimensions except the first must be explicitly specified.

82. What is the consequence of returning a pointer to a dynamically allocated variable (using new) from a function?

a) It causes a compiler error

b) It is valid, but the caller must remember to delete it to avoid memory leaks

c) The memory is automatically freed

d) It results in a dangling pointer

Correct Answer: b) It is valid, but the caller must remember to delete it to avoid memory leaks

Explanation:

Dynamically allocated memory survives function exit, shifting the responsibility of deallocation to the caller.

83. Which standard library template safely passes functions and lambdas as arguments?

a) std::vector

b) std::function

c) std::tuple

d) std::any

Correct Answer: b) std::function

Explanation:

std::function is a robust, type-safe wrapper for storing and passing any callable object.

84. Can you declare a standard C-style nested function inside another function in standard C++?

a) Yes

b) No, C++ does not support standard nested functions

c) Only if it is void

d) Only inside main

Correct Answer: b) No, C++ does not support standard nested functions

Explanation:

Standard C++ does not allow traditional nested functions, though lambda expressions can be defined locally.

85. What is an Immediately Invoked Function Expression (IIFE) in C++?

a) A macro

b) A lambda expression that is defined and immediately executed in the same statement

c) A recursive function

d) A separate thread

Correct Answer: b) A lambda expression that is defined and immediately executed in the same statement

Explanation:

By appending () to the end of a lambda definition, it executes instantly.

86. How is a C++ coroutine (C++20) different from a regular function?

a) It executes twice

b) It can suspend its execution and be resumed later

c) It bypasses the CPU

d) It only accepts string arguments

Correct Answer: b) It can suspend its execution and be resumed later

Explanation:

Coroutines introduce keywords like co_await to pause and resume execution state.

87. What distinguishes a macro from an inline function?

a) Macros are evaluated at runtime

b) Inline functions perform type checking; macros perform simple text substitution

c) Macros can only define variables

d) There is no difference

Correct Answer: b) Inline functions perform type checking; macros perform simple text substitution

Explanation:

Inline functions are type-safe and integrated into the C++ compiler, whereas macros are preprocessor text replacements.

88. Which of the following creates an alias for a function pointer in C++11?

a) typedef void(*FuncPtr)();

b) using FuncPtr = void(*)();

c) alias FuncPtr = void();

d) Both a and b are valid

Correct Answer: d) Both a and b are valid

Explanation:

Both typedef and the modern using keyword can define an alias for function pointers.

89. If you want a function parameter to act as an input-only array that the function cannot alter, what is the best signature?

a) void func(int arr[])

b) void func(const int arr[])

c) void func(int* const arr)

d) void func(const int& arr)

Correct Answer: b) void func(const int arr[])

Explanation:

Declaring the array parameter as const prevents the function from modifying its contents.

90. Can an inline function be recursive?

a) Yes, it unrolls infinitely

b) It is syntactically allowed, but the compiler generally ignores the inline request

c) No, syntax error

d) Only if depth is 1

Correct Answer: b) It is syntactically allowed, but the compiler generally ignores the inline request

Explanation:

Compilers cannot inline infinite recursion and will compile it as a standard function.

91. What is the purpose of std::bind in ?

a) To attach a variable to a port

b) To generate a new callable by partially applying arguments to an existing function

c) To combine two classes

d) To force a constant

Correct Answer: b) To generate a new callable by partially applying arguments to an existing function

Explanation:

std::bind creates a new function object binding specific values to parameters of the original function.

92. When defining default arguments in a function, where should they be specified?

a) Only in the function definition

b) Only in the function prototype (declaration)

c) In both places simultaneously

d) In the main function

Correct Answer: b) Only in the function prototype (declaration)

Explanation:

Default arguments must be specified in the declaration visible to the caller.

93. Which principle relates to finding the correct overloaded function to execute?

a) Overload Resolution

b) Type Erasure

c) Name Mangling

d) Stack Unwinding

Correct Answer: a) Overload Resolution

Explanation:

Overload resolution is the process where the compiler decides which overloaded function to invoke based on arguments.

94. What is an activation record?

a) A log of all function calls on disk

b) The data structure on the call stack containing parameters, locals, and return address

c) A database record

d) A C++20 module feature

Correct Answer: b) The data structure on the call stack containing parameters, locals, and return address

Explanation:

An activation record (stack frame) is pushed onto the stack every time a function is called.

95. Can standard C++ functions return a reference to a dynamically allocated object?

a) Yes, but it is frowned upon as it hides memory management

b) No, it will not compile

c) Yes, and memory frees automatically

d) No, new only returns ints

Correct Answer: a) Yes, but it is frowned upon as it hides memory management

Explanation:

It compiles, but makes it unintuitive for the caller to delete the underlying pointer, risking leaks.

96. How do you specify that a class method does not modify the object?

a) static void func();

b) void const func();

c) void func() const;

d) const void func();

Correct Answer: c) void func() const;

Explanation:

Placing const after the parameter list signifies that the 'this' pointer is a pointer to const.

97. Which of the following allows a function to modify an outside variable without using pointers?

a) Pass by value

b) Pass by reference

c) Static variables

d) Const parameters

Correct Answer: b) Pass by reference

Explanation:

Passing by reference (using &) gives the function direct access to the original variable.

98. What happens if a function tries to return a value but its return type is void?

a) Value is printed

b) Compiler ignores the value

c) A compile-time error occurs

d) Program crashes

Correct Answer: c) A compile-time error occurs

Explanation:

Returning a specific value inside a void function violates its signature, causing a compilation error.

99. Can you have an array of function pointers?

a) No

b) Yes, commonly used to implement state machines or dispatch tables

c) Only if they take no arguments

d) Only if they return void

Correct Answer: b) Yes, commonly used to implement state machines or dispatch tables

Explanation:

Arrays of function pointers map indices to behaviors, replacing complex switch statements.

100. What is the standard convention for preventing a function template from being instantiated with a specific type?

a) Using = delete on a template specialization

b) Using #pragma disable

c) Using a void return type

d) It cannot be prevented

Correct Answer: a) Using = delete on a template specialization

Explanation:

Providing a specialization and marking it = delete explicitly forbids that type from being used.

101. Which modern C++ feature allows returning multiple values elegantly without defining a struct?

a) std::vector

b) std::tuple

c) Multiple return keywords

d) Global references

Correct Answer: b) std::tuple

Explanation:

std::tuple allows packing multiple disparate data types into a single returnable object.

102. What is structured binding (C++17) used for in the context of functions?

a) Binding network sockets

b) Easily unpacking multiple returned values into local variables

c) Linking C code

d) Managing thread locks

Correct Answer: b) Easily unpacking multiple returned values into local variables

Explanation:

Structured binding syntax easily unpacks pairs, tuples, or structs returned by a function.

103. What is a thunk in C++?

a) An error message

b) A helper function generated by the compiler to manage virtual function calls or multiple inheritance

c) A thread variable

d) A C++ keyword

Correct Answer: b) A helper function generated by the compiler to manage virtual function calls or multiple inheritance

Explanation:

Thunks are injected by the compiler to adjust the 'this' pointer during complex method dispatch.

104. What does a function signature consist of?

a) Function name and return type only

b) Function name, parameter types, and constness, EXCLUDING return type

c) Return type, body, and variables

d) Only the parameter list

Correct Answer: b) Function name, parameter types, and constness, EXCLUDING return type

Explanation:

The signature identifies the function for overloading. It excludes the return type.

105. If you pass an array int arr[10] to a function, what is sizeof(arr) inside the function?

a) 40 bytes

b) The size of a pointer

c) 10

d) 0

Correct Answer: b) The size of a pointer

Explanation:

Because the array decays to a pointer, sizeof returns the pointer's size, not the array's.

106. What does standard C++ recommend instead of C-style variadic functions (...) for type safety?

a) void pointers

b) Macros

c) Variadic templates

d) Global arrays

Correct Answer: c) Variadic templates

Explanation:

Variadic templates offer a type-safe way to handle an arbitrary number of arguments.

107. How are template parameters expanded in a variadic template function?

a) Using a for loop

b) Using a fold expression (C++17) or recursive unpacking

c) Using the expand keyword

d) Using a switch statement

Correct Answer: b) Using a fold expression (C++17) or recursive unpacking

Explanation:

Variadic parameter packs are typically unpacked via recursion or fold expressions.

108. What is the purpose of the main function returning an integer?

a) To provide a calculation result to the user

b) To signify the execution status (success or failure) to the operating system

c) To assign a memory block size

d) Because void main is required

Correct Answer: b) To signify the execution status (success or failure) to the operating system

Explanation:

Returning 0 indicates successful execution; non-zero values represent error codes.

109. Is void main() standard C++?

a) Yes

b) No, standard C++ requires main to return int

c) Yes, on Windows

d) Yes, in embedded systems

Correct Answer: b) No, standard C++ requires main to return int

Explanation:

The C++ standard strictly mandates that the main function must have a return type of int.

110. If you do not explicitly write return 0; at the end of the main function, what happens?

a) Code fails to compile

b) Program crashes

c) The compiler implicitly inserts return 0;

d) It returns garbage

Correct Answer: c) The compiler implicitly inserts return 0;

Explanation:

If main() reaches the end without a return statement, it is treated as if return 0; was executed.

111. Which component manages the execution and memory allocation for local function variables?

a) The Heap

b) The Call Stack

c) The Data Segment

d) The Text Segment

Correct Answer: b) The Call Stack

Explanation:

The call stack automatically handles local variable memory and control flow for function calls.

112. Can a function be declared and defined in the same statement?

a) Yes, this is how inline functions and standard definitions work

b) No, they must be separated into .h and .cpp files

c) Only for void functions

d) Only for class members

Correct Answer: a) Yes, this is how inline functions and standard definitions work

Explanation:

A function can be fully defined (body included) at its point of declaration.

Ads Blocker Detected!!!

1. What is a function in C++?

2. Which keyword is used to return a value from a function?

3. What happens if a C++ function does not specify a return type?

4. What is a function prototype?

5. From which function does the execution of a C++ program begin?

6. What does a void return type signify?

7. What are formal parameters in a function?

8. What are actual parameters?

9. Which of the following is true about pass-by-value?

10. How do you pass a variable by reference in C++?

11. What happens when an array is passed to a function?

12. What is a default argument?

13. What is the rule for assigning default arguments?

14. What does a const parameter indicate?

15. What is function overloading?

16. Can two functions be overloaded solely by changing their return types?

17. What is name mangling in C++?

18. What is the purpose of the extern C block?

19. What is an inline function?

20. Which scenario makes the compiler most likely to ignore an inline request?

21. Can the main() function in standard C++ be overloaded?

22. What are the common parameters of the main() function?

23. What does argc represent in main()?

24. What is recursion?

25. What is essential for a recursive function to prevent an infinite loop?

26. What happens if a recursive function does not have a base case?

27. What is tail recursion?

28. Which of the following describes mutual recursion?

29. Is it legal for a standard C++ function to return a C-style array directly?

30. What is the danger of returning a reference to a local variable?

31. Which keyword makes a free-standing function visible only within its translation unit?

32. How are function arguments pushed onto the call stack typically in cdecl?

33. What is a function pointer?

34. What is the correct syntax for a pointer to a function returning void and taking no arguments?

35. What is a callback function?

36. In C++11, what represents generic callable objects including function pointers and lambdas?

37. What is a functor in C++?

38. What is a lambda expression in C++?

39. What do the square brackets [] represent in a lambda expression?

40. What does a capture clause of [&] signify in a lambda?

41. What does a capture clause of [=] signify in a lambda?

42. By default, variables captured by value in a lambda are:

43. Which keyword makes variables captured by value modifiable inside a lambda?

44. How do you specify the return type of a lambda explicitly?

45. What is a generic lambda (introduced in C++14)?

46. Which keyword marks a function to explicitly not throw any exceptions?

47. What does a constexpr function guarantee?

48. What is the difference between constexpr and consteval (C++20)?

49. What does the = delete syntax do to a function?

50. What is a variadic function in C++?

51. Which header is required for using old C-style variadic functions like va_list?

52. What is a function template?

53. What keyword is used to declare a function template?

54. What is template argument deduction?

55. What is template specialization?

56. What is a friend function in C++?

57. Does a friend function have a 'this' pointer?

58. Where can a friend function be declared inside a class?

59. What is a member function?

60. How is a class member function defined outside the class?

61. What is the 'this' pointer in C++?

62. What is a static member function?

63. Which of the following is true about static member functions?

64. What does a const keyword at the end of a member function declaration mean?

65. What is a virtual function?

66. What is a pure virtual function?

67. What happens if a class has at least one pure virtual function?

68. Can constructors be virtual functions?

69. Can destructors be virtual functions?

70. What does the override keyword do in C++11?

71. What does the final keyword do when applied to a member function?

72. What is the C++14 auto return type deduction?

73. If a function with an auto return type has multiple return statements, what must be true?

74. What does the [[nodiscard]] attribute do?

75. What is the use of the [[deprecated]] attribute on a function?

76. What is a trailing return type syntax?

77. In the context of exceptions, what happens if a function marked noexcept throws an exception?

78. Can a function be overloaded based strictly on whether a parameter is passed by value or passed by reference?