C++中的结构继承

Question

可以在 C++ 中继承struct吗？

Answer 1

是的， struct与class完全一样，除了默认的可访问性对于struct是public （而对于class是private的）。

Answer 2

Yes. The inheritance is public by default.

Syntax (example):

struct A { };
struct B : A { };
struct C : B { };

Answer 3

Other than what Alex and Evan have already stated, I would like to add that a C++ struct is not like a C struct.

In C++, a struct can have methods, inheritance, etc. just like a C++ class.

Answer 4

In C++, a structure's inheritance is the same as a class except the following differences:

When deriving a struct from a class/struct, the default access-specifier for a base class/struct is public. And when deriving a class, the default access specifier is private.

For example, program 1 fails with a compilation error and program 2 works fine.

// Program 1
#include <stdio.h>

class Base {
    public:
        int x;
};

class Derived : Base { }; // Is equivalent to class Derived : private Base {}

int main()
{
    Derived d;
    d.x = 20; // Compiler error because inheritance is private
    getchar();
    return 0;
}

// Program 2
#include <stdio.h>

struct Base {
    public:
        int x;
};

struct Derived : Base { }; // Is equivalent to struct Derived : public Base {}

int main()
{
    Derived d;
    d.x = 20; // Works fine because inheritance is public
    getchar();
    return 0;
}

Answer 5

Of course. In C++, structs and classes are nearly identical (things like defaulting to public instead of private are among the small differences).

Answer 6

Yes, c++ struct is very similar to c++ class, except the fact that everything is publicly inherited, ( single / multilevel / hierarchical inheritance, but not hybrid and multiple inheritance ) here is a code for demonstration

 #include<bits/stdc++.h> using namespace std; struct parent { int data; parent() : data(3){}; // default constructor parent(int x) : data(x){}; // parameterized constructor }; struct child : parent { int a , b; child(): a(1) , b(2){}; // default constructor child(int x, int y) : a(x) , b(y){};// parameterized constructor child(int x, int y,int z) // parameterized constructor { a = x; b = y; data = z; } child(const child &C) // copy constructor { a = Ca; b = Cb; data = C.data; } }; int main() { child c1 , c2(10 , 20), c3(10 , 20, 30), c4(c3); auto print = [](const child &c) { cout<<ca<<"\\t"<<cb<<"\\t"<<c.data<<endl; }; print(c1); print(c2); print(c3); print(c4); } OUTPUT 1 2 3 10 20 3 10 20 30 10 20 30