[SOLVED] Struggling to get a WideString with IntToStr

[Gizmo]

Hi

I think this is a simple one for people who get widestrings and pointers better than me. I am using a Delphi API with Lazarus (using {mode DELPHI}) and one of the functions outputs text to an output message using LPWSTR (long pointer to wide string).

What I have below does compile but I am struggling getting it to output anything (it outputs empty lines currently).

Code: Pascal  [Select][+][-]

1.  
2. function X_ProcessItem(nItemID : LongWord; lpReserved : Pointer) : integer; stdcall; export;
3. var
4.   ItemSize : Int64;
5.   ItemSizeWStr : WideChar;
6.   Buf : array[0..1000000] of WideChar;  // because I can't do array[0..Buflen-1] of WideChar for some reason)
7. begin
8.   ItemSize := XAPI_GetItemSize(nItemID); // One API call. Gets the size and returns an Int64
9.   StringToWideChar(IntToStr(ItemSize), @ItemSizeWStr, Length(ItemSizeWStr));  // IntToStr won't give me a widechar as needed for the output API function so doing this to convert.
10.   lstrcpyw(Buf, @ItemSizeWStr);  // this is from the Windows API, and it should copy the widestring to the Buffer
11.   XAPI_OutputMessage(@Buf[0], 0);  // The last API call that should output the content of the Buffer, ideally "12345" (or whatever the value of ItemSize is
12. end;      
13.  

Where am I going wrong please?

[Gizmo]

Solved by reading http://www.delphibasics.co.uk/RTL.asp?Name=StringToWideChar

thanks

[lucamar]

Wouldn't this be easier:

Code: Pascal  [Select][+][-]

1. function X_ProcessItem(nItemID : LongWord; lpReserved : Pointer) : integer; stdcall; export;
2. var
3.   ItemSize : Int64;
4.   ItemWStr : WideString;
5. begin
6.   ItemSize := XAPI_GetItemSize(nItemID); { Get the size as an Int64 }
7.   ItemWStr := IntToStr(ItemSize);        { and convert to WideString}
8.   XAPI_OutputMessage(@ItemWStr[0], 0);  // The last API call that should output the content of the Buffer, ideally "12345" (or whatever the value of ItemSize is
9. end;

It's untested but it should work. Your problem was that you were trying to use a WideChar as if it were a WideString, so use a WideString!

[Gizmo]

Thanks for the pointers there.

I'm having to use buffer 'arrays of widechars' to ensure the API is happy.