Shulou(Shulou.com)06/03 Report--

This article introduces "how to master C++ classes and objects" related knowledge, in the actual case operation process, many people will encounter such a dilemma, then let the editor lead you to learn how to deal with these situations! I hope you can read it carefully and be able to achieve something!

Assignment operator overload function 1. Operator overloading

C++ introduces operator overloading to enhance the readability of the code. operator overloading is a function with a special function name, but also has its return value type, function name and argument list, which is similar to a parameter list and an ordinary function.

Its function name is: operator + operator symbols (parameter list) that need to be overloaded.

It is important to note that:

(1) you cannot create a new operator by concatenating other symbols, such as operator$. That is, operator can only overload existing operators, and other symbols cannot be created through this function.

(2) the overloaded operator must have an Operand of a class type or an enumerated type.

(3) the meaning of operators for built-in types cannot be changed. For example, the type of a built-in integer cannot be changed.

(4) the number of parameters of the operator overloaded function is the Operand of the operator. For example, for the = = operator, its Operand is two, then the function parameter of the operator overloaded should be 2, that is, operator== (int x int y).

(5) for an operator overloaded function that is a member of a class, its argument appears to be one less than the Operand of the operator, because the function implies a formal parameter this, and the this pointer is limited to the first parameter.

(6) Grammar stipulates that there are five operators that cannot be overloaded, namely. * (pointer dereference in a member),:: (scope qualifier),? : (ternary operator),. (member (object) selection), sizeof (length operator). It is important to note that. (dereferencing operator) can be overloaded, and the operator that cannot be overloaded is the. * operator in s1.*ptr, that is, accessing the pointer member of the class and dereferencing.

Take the familiar date class as an example, for example, we want to implement the overloaded function of the = = operator:

/ / class Date {public: / / get the number of days in a certain year and month in the header file Date.h int GetDay (int year, int month) {assert (month > 0 & & month)

< 13); int Day[13] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 }; if (month == 2 && year % 4 == 0 && year % 100 != 0 || year % 400 == 0)//闰年二月 { return 29; } return Day[month]; } //全缺省的构造函数 Date(int year = 0, int month = 1, int day = 1) { _year = year; _month = month; _day = day; //判断初始化的日期是否合理 if (_month >

= 13 | | _ day > GetDay (_ year, _ month) | | _ month

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