When passing parameters by reference, which symbol is used to denote reference in C++?
- #
- @
- &
- %
In C++, the ampersand (&) is used to denote that a parameter is being passed by reference. This allows the function to directly access and modify the actual argument's memory location.
You are tasked with enhancing the performance of a critical path in an application. You identify a function that is called very frequently as a potential optimization target. Which specific aspect of the return statement could you focus on to possibly improve performance, especially considering modern C++ standards?
- Returning by value.
- Returning by pointer.
- Using return in a loop to optimize iterations.
- Returning by reference or moving.
In modern C++, when considering performance-critical paths, it's beneficial to understand the difference between returning by value and returning by reference or using move semantics. Especially with the advent of Rvalue references in C++11, returning by reference or moving can avoid unnecessary copies and lead to significant performance improvements. Returning by pointer is less idiomatic and might not convey ownership semantics clearly.
In the context of floating-point representation, what is the role of the mantissa?
- Determines the sign
- Determines the exponent
- Stores the actual digits
- Determines the base
In floating-point representation, the number is typically represented as: (-1)^sign * mantissa * (base^exponent). The mantissa is responsible for storing the actual digits of the floating-point number, while the exponent determines the position of the decimal point and the sign determines its sign.
The first commercially available C++ compiler was named _______.
- CFront
- Clang
- GCC
- Turbo C++
CFront was the first commercially available C++ compiler. It was developed by Bjarne Stroustrup at Bell Labs as a front-end to the C compiler. This compiler played a crucial role in the early evolution and popularization of C++.
How does C++ treat an enum regarding its type and size?
- As a float type with fixed size
- As an integer type with variable size
- As a class with member functions
- As a boolean type
Enums in C++ are treated as integer types. Their actual size can vary based on the compiler and the number of values they hold, but typically, they have the size of an int. C++11 introduced scoped enumerations (enum class) that offer better type safety, but fundamentally, they're still integers.
Which of the following C++ standards introduced smart pointers?
- C++03
- C++11
- C++14
- C++98
Smart pointers, like std::shared_ptr, std::unique_ptr, and std::weak_ptr, were introduced in C++11. They are part of the C++ Standard Library and are designed to manage the lifecycle of dynamically allocated objects, preventing memory leaks.
In terms of object-oriented design principles, what is typically the most significant critique against the use of friend functions?
- They break encapsulation.
- They increase execution time.
- They aren't necessary in OOP.
- They cause memory leaks.
Friend functions have the ability to access private and protected members of a class, which can be seen as a violation of the principle of encapsulation in object-oriented programming. While they offer flexibility, they can break the boundaries set by encapsulation.
You are building a configuration parser for a C++ application...
- Use std::ifstream and check its state
- Read entire file and validate before parsing
- Use regular expressions to parse
- Use std::fscanf
When using std::ifstream, it's possible to check the state of the stream (e.g., fail(), bad(), eof()) after operations. This allows for robust error handling by identifying issues like file corruption. Ensuring stream integrity before operations can prevent runtime issues.
Imagine you are developing a real-time gaming application where performance is critical. Which type of function (regular/inline) might you prefer to use for small, frequently-used utility calculations, and why?
- Regular functions due to easier debugging.
- Inline functions for performance optimization.
- Regular functions for better code organization.
- Inline functions due to easier maintenance.
Inline functions are usually preferred for small, frequently-used utility calculations in performance-critical applications like games because the compiler replaces the inline function call with the actual code, eliminating the overhead of a function call.
You are developing a financial application with various account types. How would you design the classes to achieve this and allow future modifications?
- Singleton Pattern
- Composition
- Prototype Pattern
- Inheritance and Polymorphism
Using inheritance, a base class 'Account' can be created with methods like 'withdraw', 'deposit', and 'calculateInterest'. Derived classes like 'SavingsAccount', 'CurrentAccount', etc., can then override these methods to provide specific implementations. Polymorphism ensures these methods are called appropriately.