Disassembly of a simple C + + program

  
 

   
  

  
#include<iostream>
   
  

  
using namespace std;
   
  

  
class point3d;
   
  

  
class point2d;
   
  

  
class point3d
   
  

  
{
   
  

  
private:int x; int y; int z;
   
  

  
public:
   
  
Point3D(inta= 0, intb= 0, intC= 0) :x(a),y(b),Z(C) {}
   
  

  
};
   
  

  
class point2d
   
  

  
{
   
  

  
 int a;
   
  

  
 int b;
   
  

  
public:
   
  

  
 point2d(int x=0,int y=0):a(x),b(y){}
   
  

  
 operator point3d()
   
  

  
 {
   
  

  
 return{ a,b,0 };
   
  

  
 }
   
  

  
};
   
  

  
int main()
   
  

  
{
   
  

  
 point2d z;
   
  

  
 point3d q = z;
   
  

  
 return 0;
   
  

  
 
   
  

  
}
  
 

Post Disassembly point 2d Z: (Call constructor Push 0 (Press 2 arguments) push 0lea ecx,[z] (Save Z object's address to ECX) Call point2d::p oint2d (0c01348h)
mov dword ptr [THIS],ECXThe ECX (the address of the Z object). Save to this pointer
mov Eax,dword ptr [this]. Assigns the address of the Z object to the EAXmov Ecx,dword ptr [x]; Remove the value of the variable x to save to ECXmov dword ptr [EAX],ECX. Assigns ecx=0 to the lower 4 bits of the object Z (that is, a)mov Eax,dword ptr [this]. Assigns the address of the object to the EAXmov ecx,dword ptr [y] assigns the value of the variable y to ecxmov dword ptr [EAX+4],ECX assigns the value of Y to the address of a high 4-bit object (that is, b)mov Eax,dword ptr [this], the address of the object to EAX as the return value

Point3D Q =z;

  
 

   
  

  
008538B4 lea eax,[q] ;将q的地址赋给eax
   
  

  
008538B7 push eax ;压栈.作为参数
   
  

  
008538B8 lea ecx,[z] ;将z的地址赋给ecx
   
  

  
008538BB call point2d::operator point3d (085133Eh) 
  
 

  
 

   
  

  
00853380 push ebp 
   
  

  
00853381 mov ebp,esp 
   
  

  
00853383 sub esp,0CCh 
   
  

  
00853389 push ebx 
   
  

  
0085338A push esi 
   
  

  
0085338B push edi 
   
  

  
0085338C push ecx 
   
  

  
0085338D lea edi,[ebp-0CCh] 
   
  

  
00853393 mov ecx,33h 
   
  

  
00853398 mov eax,0CCCCCCCCh 
   
  

  
0085339D rep stos dword ptr es:[edi] 
   
  

  
0085339F pop ecx ;
   
  

  
008533A0 mov dword ptr [this],ecx ;将 point2d z的地址赋给了this指针
   
  

  
return{ a,b,0 };
   
  

  
008533A3 push 0 ;0压栈
   
  

  
008533A5 mov eax,dword ptr [this] 
   
  

  
008533A8 mov ecx,dword ptr [eax+4] ;将z的a变量的值赋给ecx
   
  

  
008533AB push ecx ;ecx压栈
   
  

  
008533AC mov edx,dword ptr [this] 
   
  

  
008533AF mov eax,dword ptr [edx] ;将a的值赋给了eax中 
   
  

  
008533B1 push eax ;eax压栈
   
  

  
008533B2 mov ecx,dword ptr [ebp+8] ;取出q的地址
   
  

  
008533B5 call point3d::point3d (0851357h) ;point3d(一个q的地址.参数.3个变量参数)
   
  

  
008533BA mov eax,dword ptr [ebp+8] ;将q的地址取出来.作为返回值
   
  

  
}
  
 

From for notes (Wiz)

Disassembly of a simple C + + program