Pointer and reference similar at assembly level

kaustubh's Avatar author of Pointer and reference similar at assembly level
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This is an article on Pointer and reference similar at assembly level in C.
Pointer and reference maybe same at assembly level.
Try an experiment :

Code: C
# include<stdio.h>
int main()
{
  int i =90;
  int *pointer;
  int &reference = i; // Line 6
  pointer = &i;  
  return 0;  // Line 8
}
compile it to assembly with Microsoft c++ like this :
Code:
c:\ cl /Fa filename.cpp
or with gcc like
Code:
c:\ gcc -S -masm=intel filename.cpp
Open the asm file like c:\ notepad filename.asm

Now you can the code of i, pointer, and reference;

Code:
 Line 6
	mov	DWORD PTR _i$[ebp], 90			; int i = 90;
; Line 8
	lea	eax, DWORD PTR _i$[ebp]                  ; int &reference = i;
	mov	DWORD PTR _reference$[ebp], eax
; Line 9
	lea	ecx, DWORD PTR _i$[ebp]               ; int *pointer
	mov	DWORD PTR _pointer$[ebp], ecx    ;  pointer = &i;
you see the code for pointer is exactly same as reference .
Team Leader
16Aug2007,16:21   #2
DaWei's Avatar
That's because C doesn't have references like C++. The & is strictly an address-of operator.
Go4Expert Founder
16Aug2007,16:22   #3
shabbir's Avatar
He is using a cpp file and so the compiler is C++.
Go4Expert Member
16Aug2007,23:56   #4
kaustubh's Avatar
Quote:
Originally Posted by DaWei
That's because C doesn't have references like C++. The & is strictly an address-of operator.
Dawei i am using c++ compiler if you don't believe me see this code

Code:
#include<iostream>

int main()
{
int i =90;
  int *pointer;
  int &reference = i; 
  pointer = &i;  
  return 0;  
}
Code:
	
       mov     DWORD PTR _i$[ebp], 90			;  int i = 90

	lea	eax, DWORD PTR _i$[ebp]                  ; int &reference = i; 
	mov	DWORD PTR _reference$[ebp], eax

	lea	ecx, DWORD PTR _i$[ebp]                  ; pointer = &i;
	mov	DWORD PTR _pointer$[ebp], ecx
the code of reference is same as code of pointer.
Light Poster
25Aug2007,13:38   #5
rajkumar_singhalmca's Avatar
the pointer is very ueful when the use in the right way otherwise it can be damaged the our memory location.