这种构造是什么意思：布尔运算符==（const a＆other）const ;？

Question

I have a structure defined in the following way:

struct struct_name
{
    int x;
    region y;

    bool operator == (const struct_name& other) const;
};

I do not understand the last line in the body of the structure. What does it do?

Answer 1

Declares operator== for this struct . This operator will allow you to compare struct objects in an intuitive way:

struct_name a;
struct_name b;
if( a == b )
// ...

---

bool operator == (const struct_name& other) const;
^^^^              ^^^^^............^        ^^^^^-- the method is `const` 1
^^^^              ^^^^^............^
^^^^              ^^^^^............^--- the `other` is passed as const reference
^^^^
^^^^-- normally, return true, if `*this` is the same as `other`

1 - this means, that the method does not change any members

---

EDIT: Note, that in C++ , the only difference between class and struct is the default access and default type of inheritance (noted by @AlokSave) - public for struct and private for class .

Answer 2

It declares a function. The function's name is operator== . It returns bool and takes a single argument of type const struct_name& . It final const in the line says that it is a const member function, which means that it doesn't modify the state of the struct_name object it is called on.

This is known as operator overloading .