Learn about methods called C + + from the assembly

SRC (Debug vesion by VS2008 SP1 on XP SP3)

#include<iostream>using namespace std;class SimpleClass{public:    int x;    void HelloWorld(){        printf("hello,mao");    }};int main(int argc,char **argv){    SimpleClass myclass;    myclass.HelloWorld();    return 0;}

Post-disassembly structure

---c:\vc6\myprojects\vsclasstest\vsclasstest\bingome.cpp----------------------1: #include <iostream> 2: using namespace Std; 3:4: Class simpleclass{5:public:6: int x; 7:void HelloWorld () {00411440 push ebp 00411441 mov ebp,esp 0041 1443 Sub esp,0cch 00411449 push ebx 0041144A push esi 0041144B push EDI 0041144C push ecx 0041144D Lea edi,[ebp- 0CCH] 00411453 mov ecx,33h 00411458 mov eax,0cccccccch 0041145D rep stos dword ptr Es:[edi]//The local variable space is all initialized to 0XCC (0x33* 4=CC) (store to string addr edi by dword,repeat time was Ecx,filled-word is eax.) 0041145F pop ecx 00411460 mov dword ptr [EBP-8],ECX//ebp-8 is a variable that holds the address of the current class instance, so where does our x go? --A variable in a class is not a local variable in a function, and a method is not related to a class member. 8:printf ("Hello,mao"); 00411463 mov esi,esp 00411465 push offset string "Hello,mao" (415800h) 0041146A call Dwo Rd PTR [__imp__printf (4182BCH)]//Get address from Import table, import table IAT at 4182BCh 00411470 add esp,4 00411473 cmp esi,esp 00411475 call @ILT + 310 (__RTC_CHECKESP) (41113Bh) 9:}0041147a popEDI 0041147B pop esi 0041147C pop ebx 0041147D add esp,0cch 00411483 cmp ebp,esp 00411485 call @ILT +310 (__RTC_CHEC   KESP) (41113Bh) 0041148A mov esp,ebp 0041148C pop ebp 0041148D ret

Main function Section

17:     SimpleClass myclass;18:     myclass.HelloWorld(); 004113CE  lea ecx,[myclass]  004113D1  callSimpleClass::HelloWorld (41114Ah) 19:     return 0; 004113D6  

As you can see, when you execute a method in a class, the address () of the instantiated class is taken out, that ecx= myclass is, the compiler has introduced a hidden variable when the internal method of the class is implemented 实例化的类指针 .

A variable in a class is not a variable in a class method, and a variable in a class method access class is passed in by ECX as a hidden parameter, so there is no space in the class method to hold the class member.

Learn about methods called C + + from the assembly