On simple array

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TmX

Joined: 02 Mar 2006
Posts: 841
Location: Jakarta, Indonesia

TmX 01 Jun 2009, 06:41

Let's say I have an array like this: [10,20,30,40]

If I'm going to access the 3rd element, which is 30, in C, the code would be like this:

Code:

#include <stdio.h>

int main(){
    int array[] = {10,20,30,40};
      printf("%d",array[2]);
    return 0;
}

And this my FASM code:

Code:

format PE console 4.0

include 'win32a.inc'

entry start

section '.data' data readable
array db 10,20,30,40
fmt db "%d",0

section '.code' readable executable
start:
 mov eax,[array+2*4]
 cinvoke printf,fmt,eax
 invoke ExitProcess,0

section '.idata' data import readable writeable
library kernel32,'kernel32.dll',msvcrt,'msvcrt.dll'
import kernel32,ExitProcess,'ExitProcess'
import msvcrt,printf,'printf'

FASM says "Error: operand size doesn't match" on "mov eax,[array+2*4]"?
Any explanations? Confused

01 Jun 2009, 06:41

Picnic

Joined: 05 May 2007
Posts: 1389
Location: Piraeus, Greece

Picnic 01 Jun 2009, 06:56

Change db to dd like this.

Code:

array dd 10,20,30,40

But If you need to declare bytes instead of dwords use like this

Code:

array db 10,20,30,40
;
;
movzx eax,[array+3]

01 Jun 2009, 06:56

TmX

Joined: 02 Mar 2006
Posts: 841
Location: Jakarta, Indonesia

TmX 01 Jun 2009, 07:18

Ah OK, that works. I should take a note on that.

BTW, how can I expand the array, e.g becoming a 2D array like this:
[[10,20],[30,40],[50,60]]

So accessing array[1][1] would give you 40?

01 Jun 2009, 07:18

Picnic

Joined: 05 May 2007
Posts: 1389
Location: Piraeus, Greece

Picnic 01 Jun 2009, 07:30

Checkout here for multi-dimensional arrays..

http://board.flatassembler.net/topic.php?t=9078

01 Jun 2009, 07:30

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