An object of type std::vector can be passed to a function just like any other object. That means if we pass a std::vector by value, an expensive copy will be made. Therefore, we typically pass std::vector by (const) reference to avoid such copies. With a std::vector, the element type is …
The variable scalability challenge Consider a scenario where we want to record the test scores for 30 students and calculate the average score for the class. To do so, we’ll need 30 variables. We could define those like this: // allocate 30 integer variables (each with a different name) int …
Chapter Review Inside every (non-static) member function, the keyword is a const pointer that holds the address of the current implicit object. We can have functions return *this by reference in order to enable , where several member functions can be called on the same object in a single expression. …
Friend classes A friend class is a class that can access the private and protected members of another class. Here is an example: #include <iostream> class Storage { private: int m_nValue {}; double m_dValue {}; public: Storage(int nValue, double dValue) : m_nValue { nValue }, m_dValue { dValue } { …
In lesson , we took a look at function templates: template <typename T> // this is the template parameter declaration T max(T x, T y) // this is the function template definition for max<T> { return (x < y) ? y : x; } With a function template, we can …
A is a constructor that accepts no arguments. Typically, this is a constructor that has been defined with no parameters. Here is an example of a class that has a default constructor: #include <iostream> class Foo { public: Foo() // default constructor { std::cout << “Foo default constructed\n”; } }; …
In a previous lesson (), we mentioned that the member variables of a class are typically made private. Programmers who are learning about classes for the first time often have a hard time understanding why you’d want to do this. After all, making your variables private means they can’t be …
In the previous chapter, we covered structs (), and discussed how they are great for bundling multiple member variables into a single object that can be initialized and passed around as a unit. In other words, structs provide a convenient package for storing and moving related data values. Consider the …
The cleanup problem Let’s say that you are writing a program that needs to send some data over a network. However, establishing a connection to the server is expensive, so you want to collect a bunch of data and then send it all at once. Such a class might be …
A function and its caller communicate with each other via two mechanisms: parameters and return values. When a function is called, the caller provides arguments, which the function receives via its parameters. These arguments can be passed by value, reference, or address. Typically, we’ll pass arguments by value or by …
