C++对象内存分布(2) - 菱形继承(non virtual)
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了C++对象内存分布(2) - 菱形继承(non virtual),小编现在分享给大家,供广大互联网技能从业者学习和参考。文章包含5491字,纯文字阅读大概需要8分钟。
内容图文
1.前言
本篇文章的所有代码例子,如果是windows上编译运行,则使用的是visual studio 2013。如果是RHEL6.5平台(linux kernal: 2.6.32-431.el6.i686)上编译运行,则其gcc版本为4.4.7,如下所示:
[root@MiWiFi-R1CM ~]# gcc --versiongcc (GCC) 4.4.7 20120313 (Red Hat 4.4.7-4)
2.菱形继承类的内存分布
2.1.类的结构
菱形继承 - 重复继承
2.2.实现代码windows版本
下面的代码运行在windows 7+visual studio 2013平台上。
#include <iostream> using namespace std; class Base { public: int _iBase; char _cBase; public: Base() : _iBase(1111), _cBase('A') { } virtual void func() { cout << "Base::func()" << endl; } virtual void baseFunc() { cout << "Base::baseFunc()" << endl; } }; class Base1 : public Base { public: int _iBase1; char _cBase1; public: Base1() : _iBase1(2222), _cBase1('B') { } virtual void func() { cout << "Base1::func()" << endl; } virtual void func1() { cout << "Base1::func1()" << endl; } virtual void baseFunc1() { cout << "Base1::baseFunc1()" << endl; } }; class Base2 : public Base { public: int _iBase2; char _cBase2; public: Base2() : _iBase2(3333), _cBase2('C') { } virtual void func() { cout << "Base2::func()" << endl; } virtual void func2() { cout << "Base2::func2()" << endl; } virtual void baseFunc2() { cout << "Base2::baseFunc2()" << endl; } }; class Derive : public Base1, public Base2 { public: int _iDerive; char _cDerive; public: Derive() : _iDerive(4444), _cDerive('D') { } virtual void func() { cout << "Derive::func()" << endl; } virtual void func1() { cout << "Derive::func1()" << endl; } virtual void func2() { cout << "Derive::func2()" << endl; } virtual void deriveFunc() { cout << "Derive::deriveFunc()" << endl; } }; int main() { typedef void(*Fun)(void); int** pVtab = NULL; Fun pFun = NULL; Derive derive; pVtab = (int**)&derive; cout << "[0] Derive::Base1::_vptr->" << endl; pFun = (Fun)pVtab[0][0]; cout << " [0] "; pFun(); pFun = (Fun)pVtab[0][1]; cout << " [1] "; pFun(); pFun = (Fun)pVtab[0][2]; cout << " [2] "; pFun(); pFun = (Fun)pVtab[0][3]; cout << " [3] "; pFun(); pFun = (Fun)pVtab[0][4]; cout << " [4] "; pFun(); pFun = (Fun)pVtab[0][5]; cout << " [5] 0x" << pFun << endl; cout << "[1] Base::_iBase = " << (int)pVtab[1] << endl; cout << "[2] Base::_cBase = " << (char)(int)pVtab[2] << endl; cout << "[3] Base1::_iBase1 = " << (int)pVtab[3] << endl; cout << "[4] Base1::_cBase1 = " << (char)(int)pVtab[4] << endl; cout << "[5] Derive::Base2::_vptr->" << endl; pFun = (Fun)pVtab[5][0]; cout << " [0] "; pFun(); pFun = (Fun)pVtab[5][1]; cout << " [1] "; pFun(); pFun = (Fun)pVtab[5][2]; cout << " [2] "; pFun(); pFun = (Fun)pVtab[5][3]; cout << " [3] "; pFun(); pFun = (Fun)pVtab[5][4]; cout << " [4] 0x" << pFun << endl; cout << "[6] Base::_iBase = " << (int)pVtab[6] << endl; cout << "[7] Base::_cBase = " << (char)(int)pVtab[7] << endl; cout << "[8] Base2::_iBase2 = " << (int)pVtab[8] << endl; cout << "[9] Base2::_cBase2 = " << (char)(int)pVtab[9] << endl; cout << "[10] Derive::_iDerive = " << (int)pVtab[10] << endl; cout << "[11] Derive::_cDerive = " << (char)(int)pVtab[11] << endl; return 0; }运行结果如下:
2.3.实现代码linux版本
linux平台下的代码,与上一节中的windows代码,绝大部分是相似的,不同点仅在于linux版本中,会访问并打印出pVtab[0][6]的值。下面给出了完整的main函数。
int main() { typedef void(*Fun)(void); int** pVtab = NULL; Fun pFun = NULL; Derive derive; pVtab = (int**)&derive; cout << "[0] Derive::Base1::_vptr->" << endl; pFun = (Fun)pVtab[0][0]; cout << " [0] "; pFun(); pFun = (Fun)pVtab[0][1]; cout << " [1] "; pFun(); pFun = (Fun)pVtab[0][2]; cout << " [2] "; pFun(); pFun = (Fun)pVtab[0][3]; cout << " [3] "; pFun(); pFun = (Fun)pVtab[0][4]; cout << " [4] "; pFun(); pFun = (Fun)pVtab[0][5]; cout << " [5] "; pFun(); pFun = (Fun)pVtab[0][6]; cout << " [6] 0x" << pFun << endl; cout << "[1] Base::_iBase = " << (int)pVtab[1] << endl; cout << "[2] Base::_cBase = " << (char)(int)pVtab[2] << endl; cout << "[3] Base1::_iBase1 = " << (int)pVtab[3] << endl; cout << "[4] Base1::_cBase1 = " << (char)(int)pVtab[4] << endl; cout << "[5] Derive::Base2::_vptr->" << endl; pFun = (Fun)pVtab[5][0]; cout << " [0] "; pFun(); pFun = (Fun)pVtab[5][1]; cout << " [1] "; pFun(); pFun = (Fun)pVtab[5][2]; cout << " [2] "; pFun(); pFun = (Fun)pVtab[5][3]; cout << " [3] "; pFun(); pFun = (Fun)pVtab[5][4]; cout << " [4] 0x" << pFun << endl; cout << "[6] Base::_iBase = " << (int)pVtab[6] << endl; cout << "[7] Base::_cBase = " << (char)(int)pVtab[7] << endl; cout << "[8] Base2::_iBase2 = " << (int)pVtab[8] << endl; cout << "[9] Base2::_cBase2 = " << (char)(int)pVtab[9] << endl; cout << "[10] Derive::_iDerive = " << (int)pVtab[10] << endl; cout << "[11] Derive::_cDerive = " << (char)(int)pVtab[11] << endl; return 0; }运行结果如下:
2.4.内存分布对比
通过下面的对比图,可以看到,对于菱形非虚继承,在这两种平台上的内存分布几乎一样。
Windows 7 + Visual studio 2013 Linux RHEL6.5 + gcc 4.4.7
版权声明:本文为博主原创文章,未经博主允许不得转载。
原文:http://blog.csdn.net/shltsh/article/details/46642727
内容总结
以上是互联网集市为您收集整理的C++对象内存分布(2) - 菱形继承(non virtual)全部内容,希望文章能够帮你解决C++对象内存分布(2) - 菱形继承(non virtual)所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错,欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 gblab@vip.qq.com 举报,一经查实,本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。