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Questions and Answers
What are the primary streams used for input and output in C++?
What are the primary streams used for input and output in C++?
Which operator is used in C++ to allocate memory dynamically?
Which operator is used in C++ to allocate memory dynamically?
Which of the following accurately describes a C++ class?
Which of the following accurately describes a C++ class?
What is the purpose of the 'delete' operator in C++?
What is the purpose of the 'delete' operator in C++?
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What is a crucial difference between C structs and C++ classes?
What is a crucial difference between C structs and C++ classes?
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In which file type are C++ member functions typically defined?
In which file type are C++ member functions typically defined?
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What is the purpose of the 'using namespace std;' directive in C++?
What is the purpose of the 'using namespace std;' directive in C++?
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What distinguishes member functions in C++ from methods in Java?
What distinguishes member functions in C++ from methods in Java?
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What is the primary purpose of converting structs to classes in Object Oriented Programming?
What is the primary purpose of converting structs to classes in Object Oriented Programming?
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Which of the following lines correctly defines a private member variable in the Rectangle class?
Which of the following lines correctly defines a private member variable in the Rectangle class?
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What would happen if you tried to access the width variable in the main function as shown: r.width = 10;
What would happen if you tried to access the width variable in the main function as shown: r.width = 10;
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What is the purpose of the default constructor in the Rectangle class?
What is the purpose of the default constructor in the Rectangle class?
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Which statement about public members in the Rectangle class is true?
Which statement about public members in the Rectangle class is true?
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What should be done to define a method to calculate the area of the Rectangle?
What should be done to define a method to calculate the area of the Rectangle?
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Why can't the following line of code compile? 'cout << r.height;'.
Why can't the following line of code compile? 'cout << r.height;'.
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What role do access specifiers play in class definitions?
What role do access specifiers play in class definitions?
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Study Notes
Systems Programming Lecture 12: C++ Classes
- Lecture covers C++ classes, a key component of object-oriented programming.
- Summative submission points involve executable and library files, report PDFs, Makefile rules, code quality, output generation, example result visualizations, and result timing/memory profile graphs.
Key Differences Between C and C++
- C++ uses the iostream library for input/output, while C relies on separate functions.
- C++ employs cin, cout, and cerr for input/output, whereas C requires different I/O functions.
- C++ employs the << and >> operators for stream input/output.
- C++ uses namespaces, like std::, to group elements.
Dynamic Memory Allocation (new and delete)
- In C++, dynamic memory allocation is simplified compared to C.
-
newallocates space on the heap, eliminating the need for size specification. -
deletefrees up allocated memory. - C uses
mallocandcallocfor heap allocation, andfreeto deallocate.
Object Classes in C++
- C++ classes contain data members (attributes) and member functions (methods).
- C++ classes, similar to Java, encapsulate data and methods that operate on it.
- C++ classes do not utilize a garbage collector, unlike Java.
Object Classes in C++ (Declaration and File Organization)
- Typically, declared in a header (.h) file.
- Member functions defined in a source (.cpp) file.
- Typical source file extensions include .cpp, .cxx, .cc, and .C.
Object Oriented Programming (OOP) in C++
- In OOP, "objects" (instances of classes) can encapsulate data and methods operating on it.
- OOP is not readily achievable with C-style structs.
C++ Class Declaration Example
- Classes, structs, and
public:sections are used to create data members (e.g.,width,height). -
public:members can be accessed outside the class. -
private:members cannot be accessed outside the class.
C++ Constructors
- Constructors initialize objects.
- Default constructors can be specified explicitly.
- Some examples given show initialization lists within constructors, which allow more readable constructor code and improve efficiency by using compile-time initialization rather than run-time initialization (e.g.,
Rectangle r(2,5)).
C++ Methods (Functions)
- Functions, also known as methods, are defined as part of a class.
- A class can define multiple methods to operate on its data (e.g., the
Rectangle::Area()method for instance).
C++ Public Methods: Print()
- The
Rectangle::Print()method shows how to output the class member variables (width and height).
Default Constructor and Initialization Lists
- Initialization lists initialize data members during object creation.
- The
Rectangleclass can utilize initialization lists for efficient and precise member variable assignment.
C++ Destructors
- Destructors clean up resources when an object is destroyed.
- Destructors are automatically invoked.
- C++ destructors are designated with a tilde (
~) preceding the class name (e.g.,~Rectangle). - Automatic variables are destroyed automatically, so a destructor may not need code, though it may still sometimes be beneficial.
Passing Variables (by Value, Pointer, Reference)
- In C++, variables can be passed to functions by value, pointer, or reference.
- Pass by value does not affect the original variable outside the function.
- Pass by pointer changes the original value because the function obtains the memory address.
- Pass by reference changes the original value because the reference is an alias for the original variable.
References vs. Pointers
- References are aliases for variables; pointers hold memory addresses.
- References cannot be NULL, while pointers can.
- References have stricter value semantics.
- Pointers have greater flexibility in memory management.
C++ const Keyword
- The
constkeyword designates variables as having constant values. - Functions or variables preceded by
constmean the values or behaviors of those functions/variables cannot be changed.
Function Overloading
- Function overloading in C++ permits multiple functions with identical names but distinct parameter lists—allowing functions to perform identical operations on various data types.
Operator Overloading
- Operator overloading in C++ enables you to redefine how operators, such as
+,-,<<, or>>, behave for specific classes.
Friend functions
- A friend function isn't a member of a class, yet it has access to private class members.
- Friend functions are declared explicitly within a class as friends.
C++ Rules of Three/Five
- If a class defines a copy constructor, a destructor, or any of the other "copy" functionalities, it should likely define all of them.
Move Semantics
- Move semantics were introduced in C++11.
- The
moveconstructor is typically used to transfer resources from a temporary object to a new one (e.g., when returning a locally created object from a function). - Move Semantics are generally a good practice, ensuring objects are not unnecessarily copied in potentially expensive operations.
- Copy elision (or return value optimization) is a useful optimization that often eliminates the need for explicit move constructors/operators.
Summary (C++ Programming)
- The study material covers core C++ features: classes, pointers/references, function overloading, operators, the Rule of Three/Five, move semantics, and object destruction.
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Description
This lecture focuses on C++ classes, essential in object-oriented programming. It covers key differences between C and C++, including input/output mechanisms, dynamic memory allocation, and namespace usage. Summative submission points are also discussed, emphasizing code quality and output generation.
