When making some windows program with FPC2.0.4 using sysutils, I
encountered a few problems that I tracked down to some (by me)
unexpected behaviour of the compiler. The documentation is not clear on
these points. So may I ask if the following is intentional or rather
some bug.
Q1.
When trying to open a file that was not there with this program:
----------------------------------
program test;
uses sysutils;
var n: longint; f: THandle; buf: array[0..100] of byte;
begin
f:=FileOpen('notafile', fmOpenRead);
writeln('f=',f);
n:=FileRead(f, buf, 50);
writeln('n=',n);
end.
-----------------------------------
The file handle was returned as some positive value, while n was
returned -1.
I would expect the file handle to be returned as -1 (when file is not
found).
Otherwise there would be no meaning of testing the file handle?
Q2.
When using a dynamic array a in the program line
FileWrite(f, a, bytecount)
I had unexpected data written to the file, while the line
FileWrite(f, a[0], bytecount)
did what I wanted.
That may be logical, if a is a pointer, while a[0] is the first element
of the array.
But it is different from static arrays, where a acts as the first
element of the array.
Also sizeof(a) returns the full size of the array with a static array,
but always 4 with a dynamic array.
If this is intentional, couldn't it be stated in the documentation?
Finally I would like to know:
What happens to a dynamic array if it is resized?
Are the old data copied into a new larger space of memory, and the old
memory freed, such that the elements of the array are still contiguous
in memory?
Hans Maartensson
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