Which of the following smart pointers does not take ownership of the pointed object?
- unique_ptr
- shared_ptr
- weak_ptr
- auto_ptr
weak_ptr is a smart pointer that holds a non-owning reference to an object managed by shared_ptr. It doesn't affect the reference count and won't prevent the object from being deleted.
Imagine you're working on a large-scale software project involving numerous classes. Some classes are instantiating objects of another, and suddenly an object is accidentally deleted. What techniques or principles might be used to safeguard against accidental deletion in such a situation?
- Use of smart pointers.
- Overloading the delete operator.
- Enabling strict type-checking.
- Always use dynamic allocation.
Smart pointers in C++ are template classes that manage the lifetime of dynamically allocated objects. They ensure that the objects they manage are properly deleted, thus preventing accidental deletions or memory leaks. Overloading the delete operator or enabling strict type-checking wouldn't inherently prevent accidental deletions.
What is the output of a function with a void return type?
- An integer
- A floating point number
- Nothing
- A character
In C++, a function declared with a void return type does not return any value. It is used when the function needs to perform an action but doesn't need to send any data back to the calling function.
Which of the following is a correct way to declare a function pointer in C++?
- int func()
- int *func()
- int (*func)()
- int &func()
In C++, a function pointer points to the address of a function. The correct syntax for declaring a function pointer is type (*pointer_name) (parameter list). In the given options, int (*func)() is the correct way to declare a function pointer returning an int.
What is the significance of the "default" case in a switch-case statement?
- It handles unspecified cases
- It serves as the primary case to be executed
- It is mandatory for all switch-case structures
- Acts as the else part in if-else structures
The "default" case in a switch-case statement is executed when none of the provided "case" conditions match the switch expression's value. It serves as a fallback and handles unspecified or unexpected values, ensuring that the switch has a response for all potential input. It is similar to the "else" in if-else.
The loop do { /* code */ } while(_______); will always execute the code block at least once.
- FALSE
- 1
- TRUE
- sometimes
The "do-while" loop in C++ always executes its body once before checking the condition. So even if the condition in the "while" part is "false", the body of the loop will execute once. This differentiates it from the "while" loop which checks the condition before the first execution.
Which of the following scenarios is most suitable for using a switch-case statement?
- When comparing string values.
- When there are many conditions that can occur in any order.
- When the conditions are based on a range of values.
- When dealing with enumerated values.
The switch-case structure in C++ is best suited for scenarios where a single variable's value needs to be checked against a series of constants, often seen with enumerated values. It's a cleaner and more readable alternative to a long series of if-else statements in such cases.
You are optimizing a recursive algorithm for a real-time system where function call overhead is a critical concern. What strategy might be most effective in reducing the function call overhead while maintaining the logical structure of the algorithm?
- Use inline functions.
- Optimize the algorithm's base cases.
- Introduce parallel processing.
- Rely on external libraries.
Function call overhead is the extra time and resources needed when a function is called. Using inline functions can help reduce this overhead, especially in recursive algorithms, because the function's code gets inserted (or "inlined") at each point where the function is called, eliminating the need for the typical call and return process, which can be resource-intensive.
How would you implement a loop that executes a specific number of times and uses an iterator?
- Use a while loop and initialize the iterator outside the loop.
- Use a range-based for loop.
- Use a for loop and compare the iterator to the container's end iterator.
- Use recursive function calls.
To execute a loop for a specific number of times using an iterator, a common approach is to use a for loop. You initialize the iterator before the loop starts, use the loop's condition to check against the container's end iterator, and increment the iterator within the loop's iteration expression.
When dealing with binary files, the ios::binary mode should be used in conjunction with another mode such as _______.
- ios::in
- ios::out
- ios::app
- ios::trunc
When working with binary files in C++, the ios::binary mode is often paired with another mode to specify the operation, such as ios::out for writing or ios::in for reading. This ensures that the file is treated as a binary file.