Hello everyone,
I've just joined this form in to learn assembly
I'm currently coding a few task set out for me (by myself...)
And I need to be able to take a substring (this being an array of bytes) and copy that substring into another buffer
But I've no idea on how to split a string in two. Does anyone have any tips for me, or even a working example to illustrate the idea?
Here's how it should look in pseudo code:
string str "This is some string" ; initialize our string
string buffer (?) ; out buffer
int someloc = find("some", str) ;find and copy the location of "some" inside string str and save it in someloc
buffer = copy substr(str, someloc, sizeof str); copy the contents of str, starting at someloc, with the size of str into buffer
Thanks in advance
-SCHiM
Hi SCHiM,
Here is a quick example for you. To get information about MASM32 library functions :
\masm32\help\masmlib.chm
.386
.model flat,stdcall
option casemap:none
include \masm32\include\windows.inc
include \masm32\include\kernel32.inc
include \masm32\include\user32.inc
include \masm32\include\masm32.inc
includelib \masm32\lib\kernel32.lib
includelib \masm32\lib\user32.lib
includelib \masm32\lib\masm32.lib
START_POS equ 1 ; Starting position to search for the substring = 1
.data
szMainStr db 'The MASM forum',0 ; String to be searched
szSubStr db 'MASM',0 ; Substring to search
; for within the main string
capt db 'Copied substring',0
.data?
buffer db 100 dup(?)
.code
start:
invoke InString,START_POS,ADDR szMainStr,ADDR szSubStr
; search for the substring "MASM"
; If the function succeeds
; it returns the 1 based index of the start
; of the substring or 0 if no match is found.
dec eax ; 1 based index -> 0 based index
add eax,OFFSET szMainStr
invoke lstrcpyn,ADDR buffer,eax,10 + 1
; 10 = sizeof(MASM forum) , 1 = sizeof(NULL)
invoke MessageBox,0,ADDR buffer,ADDR capt,MB_OK
invoke ExitProcess,0
END start
Whoa,
thank you Vortex!
That was
exactly what I was looking for!!
But I have a question
What does this mean:
Quote ; it returns the 1 based index of the start
; of the substring or 0 if no match is found.
Nevermind, It returns a string starting at the string that was to be found +1 right?
So if I deleted the line, dec eax, it yould return ASM forum right?
Quote from: SCHiM on October 10, 2010, 11:55:54 AM
So if I deleted the line, dec eax, it yould return ASM forum right?
Yep that's right
Hi SCHiM,
You are right. Removing the line dec eax will return ASM forum. In daily programming practice, you use 0 based indexes to manipulate NULL terminated strings. This is why eax is decremented by one.