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This article mainly explains "C++ class preliminary constant member function and constructor initial value list analysis", the explanation content in the article is simple and clear, easy to learn and understand, please follow the small series of ideas slowly in-depth, together to study and learn "C++ class preliminary constant member function and constructor initial value list analysis" bar!

header file mycpp.h

#include

classSales_data{

//friend function range declaration

friendstd::istream&read(std::istream&is,Sales_data&item);

friendstd::ostream&print(std::ostream&os,Sales_data&item);

public:

//constructor overrides built-in initialization values,: to {represents a list used to initialize member variables, called constructor initializer list

Sales_data(conststd::string&s="",constunsignedn=0,

constdoublep=0.0):bookNo(s),units_sold(n),revenue(p*n){};

//object is a constant, return must be a const, for example: instantiate a constant object constSales_dataconst_item;

std::stringisbn()const;

//Add a Sales_data object to another Sales_data object

Sales_data&combine(constSales_data&);

//Find the average price of the book sold

doubleavg_price()const;

private:

//built-in initialization is an empty string, because it is not a basic type, pointer and reference.

std::stringbookNo;//Basic type, built-in initialization undefined

unsignedintunits_sold;

doublerevenue;};

//declaration of a friend function; note that the declaration in the inside only indicates a range, indicating that the friend function can access objects of this class

std::istream&read(std::istream&is,Sales_data&item);

std::ostream&print(std::ostream&os,Sales_data&item);

Source file mycpp.cpp #include main function

intmain()//instantiate a constant object Thank you for reading, the above is the "C++ class preliminary constant member function and constructor initialization list analysis" content, after learning this article, I believe that we have a deeper understanding of the C++ class preliminary constant member function and constructor initialization list analysis, the specific use of the situation also needs to be verified by practice. Here is, Xiaobian will push more articles related to knowledge points for everyone, welcome to pay attention!

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