7.3: Structures in C++ (cont'd)

Last updated
Save as PDF

Page ID: 34673

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

2) When deriving a struct from a class/struct, default access-specifier for a base class/struct is public. And when deriving a class, default access specifier is private.
For example program 3 fails in compilation and program 4 works fine.

// Program 3
#include <iostream>
using namespace.std;

class Base {
    public:
    int x;
};

class Derived : Base { }; // is equilalent to class Derived : private Base {}

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

So...if we use a struct instead of class we get a different result

// Program 4
#include <iostream>
using namespace std;

class Base {
    public:
        int x;
};

struct Derived : Base { }; // is equilalent to struct Derived : public Base {}

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

Adapted from:
"Structure vs class in C++" by roopkatha, Geeks for Geeks is licensed under CC BY-SA 4.0