How does the return statement interact with constructors or destructors in C++?
- It can exit a constructor prematurely.
- It causes the destructor to be called immediately.
- It can be used to return a value from the constructor.
- It has no use in constructors and destructors.
Constructors don't return values, so the return statement isn't used to return a value. However, it can be used to exit a constructor prematurely under certain conditions. Destructors also don't return values, and the use of a return statement in them would be to exit early, which is very rare.
In binary file operations, to write data of various data types, you use the _______ function.
- write
- fwrite
- push
- output
The write function is used in C++ for binary file operations. It allows the user to write data of various data types to a file. Unlike formatted output, write writes raw data bytes to the file.
What is the primary purpose of function templates in C++?
- Code obfuscation
- Memory conservation
- Code reusability
- Exception handling
Function templates in C++ enable the creation of functions that can operate on different data types without having to rewrite the entire function for each type. This promotes code reusability and reduces redundancy.
Which STL container provides constant time access to elements but may take linear time to insert a new element?
- std::vector
- std::queue
- std::array
- std::list
The std::vector container provides constant time (O(1)) access to elements using random access iterators. However, insertions (especially in the middle or at the beginning) might take linear time (O(n)) as elements need to be shifted to make space for the new element.
Consider a class hierarchy with Base and Derived classes. An object of Derived throws an exception that is caught in a catch block for Base exceptions. What considerations might be relevant to the use of dynamic_cast inside the catch block?
- Checking the type of the exception.
- Re-throwing the exception.
- Modifying the caught object in the catch block.
- Use of multiple inheritance.
When an exception of Derived type is caught as its base type, using dynamic_cast can help determine the exact type of the caught exception. This can be useful if you want to take specific actions based on the exact type of the exception. Remember, dynamic_cast will return a nullptr if the cast is not valid for pointers or throw a std::bad_cast exception for references, so it's essential to check for these cases.
What would be the result of instantiating a class template with a user-defined type that does not meet the template’s expected type requirements?
- A runtime error
- A compilation error
- The template would adapt automatically
- The system would crash
Instantiating a class template with a type that doesn't meet the template's requirements would result in a compilation error. Templates rely on the types they are instantiated with to adhere to specific criteria. If those criteria aren't met, the compiler will produce an error message indicating the discrepancies.
When using the logical AND operator, if the left operand is false, the right operand is _______ evaluated.
- always
- sometimes
- never
- conditionally
In C++, the logical AND (&&) operator employs short-circuit evaluation. If the left operand is false, the right operand isn't evaluated because the overall result will already be false.
In C++, if a class makes a non-member function its friend, that function gets the ability to access the _______ and _______ members of the class.
- public, private
- private, protected
- public, static
- static, protected
In C++, when a non-member function is declared as a friend of a class, it can access both private and protected members of that class. Public members are accessible to all functions, so the unique ability granted by the friendship is access to the private and protected members.
In which scenarios could the use of goto be considered acceptable or even advisable?
- To enhance the readability of deeply nested loops.
- To replace exception handling mechanisms.
- For breaking out of multiple nested loops.
- To implement recursive functions.
While the use of "goto" is generally discouraged in modern programming due to making code harder to read and maintain, there are rare cases, like breaking out of multiple nested loops or complex error handling before exceptions were widely adopted, where its use might be considered.
In C++, _______ functions cannot be virtual.
- inline
- recursive
- overloaded
- default
Inline functions in C++ are expanded at the place where they are called, rather than being invoked. Because of this, they cannot be virtual as the virtual mechanism relies on function calls.