简介

本文主要介绍在C++中struct与class的主要区别

默认访问权限

• class的默认访问权限是private
• struct的默认访问权限是public

例程

#include <iostream>
class CTest
{
    int class_member; //默认访问属性：private
};
struct STest
{
    int struct_member; //默认访问属性:public
};
int main()
{
    CTest classTest;
    STest structTest;
        //提示错误：member "CTest::class_member" is inaccessible
    //classTest.class_member = 30; 
    structTest.struct_member = 10;
    std::cout << "struct's member: " << structTest.struct_member << "\n";
    system("pause");
    return 0;
}
输出值：
struct's member: 10

默认的继承访问权限

• class的默认继承访问权限是private
• struct的默认继承访问权限是public

例程

#include <iostream>
class CTest
{
  public:
    int class_member;
};

class CDerived :CTest // default access specifier is private
{
};

struct STest
{
    int struct_member;
};

struct SDerived :STest //defautl access specifier is public
{
};


int main()
{
    SDerived s_derived;
    CDerived c_derived;
    s_derived.struct_member = 100;
    //Error:class "CDerived" has no member "struct_member"
    // because default access specifier is private for class
    //c_derived.struct_member = 200;
    std::cout << "s_derived.struct_member= " << s_derived.struct_member << "\n";
    return 0;
}
//输出结果
s_derived.struct_member= 100

struct与class之间混合继承

1. 什么是混合继承？
   答：好吧，这是我自己想的，指通过struct去继承class,或通过class去继承struct

• 通过struct默认继承class,继承方式为public继承
• 通过class默认继承struct,继承方式为private继承

例程

#include <iostream>
class CTest
{
public:
    int class_member;
};

struct SDerivedClass :CTest // 相当于 struct sDerivedClass: public CTest{}；
{
};

struct STest
{
    int struct_member;
};

class CDerivedStruct :STest // 相当于class CDerivedStruct: private STest{}；
{
};

int main()
{
    SDerivedClass sDerived;
    CDerivedStruct cDerived;
    sDerived.class_member = 100;
    //Error: "struct_member" is not a member of "CDerived"
    //cDerived.struct_member = 200;
    std::cout << "sDerived.class_member: " << sDerived.class_member << "\n";
    return 0;
}
输出结果：
sDerived.class_member: 100