Strings Degrading??

[RedGhost]

hey i cant explain this

Code Select Expand


szFileName  BYTE 255, 0 ;will hold the filename

;get the path
push 255
push offset szFileName
push NULL
call GetModuleFileName

;get the strlen
push offset szFileName
call lstrlen

;change the extension in the string to .dll
mov [szFileName+eax-3], 'd'
mov [szFileName+eax-2], 'l'
mov [szFileName+eax-1], 'l'


now a simple test

Code Select Expand



push MB_OK
push NULL
push offset szFileName
push NULL
call MessageBox



the string is correct !
but if i try to use the string again, it screws up majorly
eg: i call the EXACT same messagebox code as above
but this time it prints like "C:\Doc" instead of the full path

[hitchhikr]

You're only allocated 2 bytes with the values 255 for the first and 0 for the second one, use this instead:

Code Select Expand


; alloc an array of 255 bytes
szFileName  BYTE 255 dup(0) ;will hold the filename


Also you should use MAX_PATH (defined in Windows.inc) constant instead of 255.

[RedGhost]

You're only allocated 2 bytes with the values 255 for the first and 0 for the second one, use this instead:

Code Select Expand


; alloc an array of 255 bytes
szFileName  BYTE 255 dup(0) ;will hold the filename


Also you should use MAX_PATH (defined in Windows.inc) constant instead of 255.

works thanks, was only chapter 4 of the masm programmers guide

dup is chapter 5 xD