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TheGood
PostPosted: December 30th, 2008, 1:23 am 
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Joined: July 30th, 2007, 11:32 pm
Posts: 581
As the title says, I need the most efficient (read, fastest) way to retrieve a string if you only know its address and its length.
This is what I have right now:

Code:
sTest := "This is a test sentence."

MsgBox % PtrToStr(&sTest, StrLen(sTest))   ;%

ExitApp

PtrToStr(ptr, len) {
   VarSetCapacity(s, len, 0)
   Loop %len%
      s .= Chr(*(ptr + A_Index - 1))
   Return s
}

Is there a faster way to do this?

Edit: I forgot to add, I tried messing around with RtlCopyString and RtlCopyBytes, but I get an ErrorLevel of -4 (function not found)


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Lexikos
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PostPosted: December 30th, 2008, 1:49 am 
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Joined: October 17th, 2006, 4:15 pm
Posts: 7502
Location: Australia
If the string is always null-terminated (as with all AutoHotkey strings), the easiest way is:
Code:
sTest := "This is a test sentence."
MsgBox % DllCall("MulDiv", int, &sTest, int, 1, int, 1, str)
MulDiv(x,1,1) returns x unmodified, but DllCall interprets the return value as a string.

If the string isn't null-terminated or you want only a portion of the string, you may use lstrcpyn via DllCall.


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TheGood
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PostPosted: December 30th, 2008, 2:15 am 
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Joined: July 30th, 2007, 11:32 pm
Posts: 581
Lexikos wrote:
MulDiv(x,1,1) returns x unmodified, but DllCall interprets the return value as a string.

Very interesting behaviour. Is that an AHK thing, or the dll itself? Is it because AHK knows it's a string pointer that was passed and not any number?


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TheGood
 Post subject:
PostPosted: December 30th, 2008, 2:22 am 
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Joined: July 30th, 2007, 11:32 pm
Posts: 581
Sorry, didn't see the "str" in the return type parameter


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SKAN
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PostPosted: January 5th, 2009, 11:59 am 
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Joined: December 26th, 2005, 4:40 pm
Posts: 8776
Lexikos wrote:
Code:
sTest := "This is a test sentence."
MsgBox % DllCall("MulDiv", int, &sTest, int, 1, int, 1, str)
MulDiv(x,1,1) returns x unmodified, but DllCall interprets the return value as a string.


:shock: :D Thanks!

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