[c++] Struct inheritance in C++

Can a struct be inherited in C++?

This question is related to c++ inheritance struct

The answer is


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;
}

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

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#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 = C.a;
        b = C.b;
        data = C.data;
    }
};
int main()
{
   child c1 ,
         c2(10 , 20),
         c3(10 , 20, 30),
         c4(c3);

    auto print = [](const child &c) { cout<<c.a<<"\t"<<c.b<<"\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
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Of course. In C++, structs and classes are nearly identical (things like defaulting to public instead of private are among the small differences).


Yes, struct is exactly like class except the default accessibility is public for struct (while it's private for class).


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.


Yes. The inheritance is public by default.

Syntax (example):

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

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