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#include <iostream>
#include <stdio.h>
/*
?* 多重继承无函数覆盖
?*/
class Base1
{
?? ?public:
?? ??? ?virtual void function_1()
?? ??? ?{
?? ??? ??? ?printf("Base1 function_1...\n");
?? ??? ?}
?? ??? ?virtual void function_2()
?? ??? ?{
?? ??? ??? ?printf("Base1 function_2...\n");
?? ??? ?}
?? ?
};
class Base2 : public Base1
{
?? ?public:
?? ??? ?virtual void function_3()
?? ??? ?{
?? ??? ??? ?printf("Base2 function_3...\n");
?? ??? ?}
?? ??? ?virtual void function_4()
?? ??? ?{
?? ??? ??? ?printf("Base2 function_4...\n");
?? ??? ?}
?? ?
};
class Sub :? Base2
{
?? ?public:
?? ??? ?virtual void function_5()
?? ??? ?{
?? ??? ??? ?printf("Sub function_5...\n");
?? ??? ?}
?? ??? ?virtual void function_6()
?? ??? ?{
?? ??? ??? ?printf("Sub function_6...\n");
?? ??? ?}
};
int main(int argc, char ** argv)
{
?? ?Sub sub;
?? ?printf("size = %d\n", sizeof(class Sub));?? ?// 4。 直接继承一个父类，所以只有一个虚函数表
?? ?printf("sub address is %x.\n", &sub);?? ??? ?// this 指针，是堆栈里面的地址。虚表的地址不是this指针，是this指针的前四个字节。
?? ?/* 对象的前4字节是第一个Base1的虚表 */
?? ?printf("sub virtual table address is:%x\n", *(int*)&sub);? ??? ??? ?
?? ?typedef void(*pfunction)(void);
?? ?
?? ?pfunction pf;
?? ?for (int i = 0; i < 6; i++) {
?? ??? ?int temp = *((int*)(*(int*)&sub) + i);?? ?
?? ??? ?if (temp == 0) {
?? ??? ??? ?break;
?? ??? ?}
?? ??? ?pf = (pfunction)temp;
?? ??? ?pf();
?? ?}
?? ?return 0;
}
/*
?? ?sub address is bfa78630.
?? ?sub virtual table address is:8048a48
?? ?Base1 function_1...
?? ?Base1 function_2...
?? ?Base2 function_3...
?? ?Base2 function_4...
?? ?Sub function_5...
?? ?Sub function_6...
?*/
#if 0
1.覆盖的是哪个在哪个虚表里；
sub对象
?? ?---------------?? ??? ??? ?-----------------
?? ?| 0x123245??? |?? ?--------->?? ??? ?| 0x123456?? ?|?? ?Base1:function_1
?? ?---------------?? ??? ??? ?-----------------
?? ?| ....??????? |?? ??? ??? ?| 0x123457?? ?|?? ?Base1:function_2
?? ?---------------?? ??? ??? ?-----------------
?? ?| ....?? ?????? |?? ??? ??? ?| 0x123458?? ?|?? ?Base2:function_3
?? ?---------------?? ??? ??? ?-----------------
?? ?| ....??????? |?? ??? ??? ?| 0x123457?? ?|?? ?Base2:function_4
?? ?---------------?? ??? ??? ?-----------------
?? ?| ....?? ?????? |?? ??? ??? ?| 0x123457?? ?|?? ?Sub:function_5
?? ?---------------?? ??? ??? ?-----------------
?? ?| 其它成员???? |?? ??? ??? ?| 0x123457?? ?|?? ?Sub:function_6
?? ?---------------?? ??? ??? ?-----------------
?? ?| ....?? ?????? |?? ??? ??? ?| 0x000000?? ?|
?? ?---------------?? ??? ??? ?-----------------
int main(int argc, char ** argv)
{
?8048700:?? ?55????????????????? ??? ?push?? %ebp
?8048701:?? ?89 e5?????????????? ??? ?mov??? %esp,%ebp
?8048703:?? ?83 e4 f0??????????? ??? ?and??? $0xfffffff0,%esp
?8048706:?? ?83 ec 20??????????? ??? ?sub??? $0x20,%esp
?? ?Sub sub;
?8048709:?? ?8d 44 24 10???????? ??? ?lea??? 0x10(%esp),%eax
?804870d:?? ?89 04 24??????????? ??? ?mov??? %eax,(%esp)
?8048710:?? ?e8 89 01 00 00????? ??? ?call?? 804889e <_ZN3SubC1Ev>
?? ?printf("size = %d\n", sizeof(class Sub));?? ?// 4。 直接继承一个父类，所以只有一个虚函数表
?8048715:?? ?c7 44 24 04 04 00 00 ?? ?movl?? $0x4,0x4(%esp)
?804871c:?? ?00
?804871d:?? ?c7 04 24 e0 89 04 08 ?? ?movl?? $0x80489e0,(%esp)
?8048724:?? ?e8 a7 fe ff ff????? ??? ?call?? 80485d0 <printf@plt>
?? ?printf("sub address is %x.\n", &sub);?? ??? ?// this 指针，是堆栈里面的地址。虚表的地址不是this指针，是this指针的前四个字节。
?8048729:?? ?8d 44 24 10???????? ??? ?lea??? 0x10(%esp),%eax
?804872d:?? ?89 44 24 04???????? ??? ?mov??? %eax,0x4(%esp)
?8048731:?? ?c7 04 24 eb 89 04 08 ?? ?movl?? $0x80489eb,(%esp)
?8048738:?? ?e8 93 fe ff ff????? ??? ?call?? 80485d0 <printf@plt>
?? ?/* 对象的前4字节是第一个Base1的虚表 */
?? ?printf("sub virtual table address is:%x\n", *(int*)&sub);? ??? ??? ?
?804873d:?? ?8d 44 24 10???????? ??? ?lea??? 0x10(%esp),%eax
?8048741:?? ?8b 00?????????????? ??? ?mov??? (%eax),%eax
?8048743:?? ?89 44 24 04???????? ??? ?mov??? %eax,0x4(%esp)
?8048747:?? ?c7 04 24 00 8a 04 08 ?? ?movl?? $0x8048a00,(%esp)
?804874e:?? ?e8 7d fe ff ff????? ??? ?call?? 80485d0 <printf@plt>
?? ?typedef void(*pfunction)(void);
?? ?
?? ?pfunction pf;
?? ?for (int i = 0; i < 6; i++) {
?8048753:?? ?c7 44 24 1c 00 00 00 ?? ?movl?? $0x0,0x1c(%esp)
?804875a:?? ?00
?804875b:?? ?eb 35?????????????? ??? ?jmp??? 8048792 <main+0x92>
?? ??? ?int temp = *((int*)(*(int*)&sub) + i);?? ?
?804875d:?? ?8b 44 24 1c???????? ??? ?mov??? 0x1c(%esp),%eax
?8048761:?? ?8d 14 85 00 00 00 00 ?? ?lea??? 0x0(,%eax,4),%edx
?8048768:?? ?8d 44 24 10???????? ??? ?lea??? 0x10(%esp),%eax
?804876c:?? ?8b 00?????????????? ??? ?mov??? (%eax),%eax
?804876e:?? ?01 d0?????????????? ??? ?add??? %edx,%eax
?8048770:?? ?8b 00?????????????? ??? ?mov??? (%eax),%eax
?8048772:?? ?89 44 24 18???????? ??? ?mov??? %eax,0x18(%esp)
?? ??? ?if (temp == 0) {
?8048776:?? ?83 7c 24 18 00????? ??? ?cmpl?? $0x0,0x18(%esp)
?804877b:?? ?75 02?????????????? ??? ?jne??? 804877f <main+0x7f>
?? ??? ??? ?break;
?804877d:?? ?eb 1a?????????????? ??? ?jmp??? 8048799 <main+0x99>
?? ??? ?}
?? ??? ?pf = (pfunction)temp;
?804877f:?? ?8b 44 24 18???????? ??? ?mov??? 0x18(%esp),%eax
?8048783:?? ?89 44 24 14???????? ??? ?mov??? %eax,0x14(%esp)
?? ??? ?pf();
?8048787:?? ?8b 44 24 14???????? ??? ?mov??? 0x14(%esp),%eax
?804878b:?? ?ff d0?????????????? ??? ?call?? *%eax
?? ?typedef void(*pfunction)(void);
?? ?
?? ?pfunction pf;
?? ?for (int i = 0; i < 6; i++) {
?804878d:?? ?83 44 24 1c 01????? ??? ?addl?? $0x1,0x1c(%esp)
?8048792:?? ?83 7c 24 1c 05????? ??? ?cmpl?? $0x5,0x1c(%esp)
?8048797:?? ?7e c4?????????????? ??? ?jle??? 804875d <main+0x5d>
?? ??? ?pf = (pfunction)temp;
?? ??? ?pf();
?? ?}
?? ?return 0;
?8048799:?? ?b8 00 00 00 00????? ??? ?mov??? $0x0,%eax
}
?804879e:?? ?c9????????????????? ??? ?leave ?
?804879f:?? ?c3????????????????? ??? ?ret
#endif
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