Which of the following is a correct statement about friend functions in C++?
- They are member functions of a class
- They can be inherited by derived classes
- They always improve performance of the program
- They do not have access to the 'this' pointer of the class
In C++, the 'this' pointer is an implicit pointer to the object on which a member function is called. Since friend functions are not member functions of a class, they do not have access to this pointer. They operate as external functions with special access permissions.
In a C++ application, you have a stream of data being logged...
- Write to a temporary file first
- Use std::ofstream::flush after every write
- Use file locking mechanisms
- Implement journaling or write-ahead logging
Implementing journaling or write-ahead logging means changes are first logged to a separate, sequential log. In case of failures, this log can be used to bring the file back to a consistent state. This provides a safeguard against data corruption or loss during unforeseen events.
You are designing a complex numerical algorithm with multiple cooperating classes that need to share internal data for efficiency. How might the friend keyword be used effectively in this context?
- Use the friend keyword for all member functions.
- Limit the use of friend to only those classes/functions that strictly require access.
- Use the friend keyword with external utility functions only.
- Declare all classes as friends of each other.
The friend keyword should be used judiciously. By limiting its use only to those classes or functions that genuinely need access, you maintain a degree of encapsulation and make the design intent clear, ensuring that only necessary components have deeper access.
A function without any parameters is declared with the keyword _______ in the parentheses.
- auto
- void
- int
- default
When declaring a function with no parameters in C++, the keyword "void" is used within the parentheses to explicitly state that no arguments are expected.
Considering cache efficiency, which STL container will provide the fastest element access and iteration in most cases?
- std::list
- std::deque
- std::vector
- std::set
std::vector is a dynamic array implementation. Due to its contiguous memory storage, it provides the best cache locality among the listed STL containers. This leads to faster element access and iteration, especially when compared to non-contiguous storage containers like std::list or node-based containers like std::set.
What feature of C++ templates allows you to provide a specific implementation for particular data types when certain types require a different implementation for optimal performance in a class template?
- Template specialization
- Template instantiation
- Function overloading
- Class inheritance
Template specialization is a feature in C++ that allows developers to define a different implementation of a template for a specific data type. This is especially useful when certain data types require unique handling or optimization compared to the general template definition.
What does the struct keyword allow a C++ programmer to do?
- Execute a set of statements repeatedly
- Connect to databases
- Create a group of variables under one name
- Create a virtual function
The struct keyword in C++ allows a programmer to define a composite data type that groups variables of different data types under a single name. This makes it easier to organize related data. Initially in C, struct was used to define a simple group, but in C++ it's similar to a class.
In what situation might explicit template specialization be used in C++?
- When all versions of the template should behave the same.
- When a specific version of a template requires different behavior.
- When templates are used with multiple inheritance.
- When we need to add more template parameters.
Explicit template specialization allows for defining a different implementation of a template for a specific type or set of types. This is particularly useful when a general template definition would be correct for most types but not for a specific type or set of types. For instance, if most types can be handled with a general algorithm, but one type requires a more optimized or different approach, explicit specialization can be used for that type.
Using continue in a while loop will skip to the _______.
- end of the loop
- beginning of the loop
- next iteration
- previous iteration
The continue statement, when encountered in a loop (like a while loop), will skip any subsequent statements in the current iteration and jump to the beginning of the next iteration.
What is the primary reason behind certain languages optimizing tail recursion?
- To improve memory efficiency
- To make code look cleaner
- To speed up compilation time
- To allow deeper recursion depth
Tail recursion optimization, often referred to as Tail Call Optimization (TCO), primarily serves to improve memory efficiency. When a recursive call is the last thing a function does (tail recursion), some languages can optimize it to reuse the current function's stack frame for the next function call. This can lead to significant savings in stack space, especially for deep recursive calls. It allows recursion-intensive algorithms to run without consuming as much memory or leading to a stack overflow.