I have an integer with length 8, an example could be 12345678. I need to turn this into an array of bytes such as xx yy zz gg
how do i go about converting this in pascal?
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1similar question stackoverflow.com/questions/13634240/…Sam– Sam2013-08-07 04:36:25 +00:00Commented Aug 7, 2013 at 4:36
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1 Answer
In modern pascal, you can just cast the value, using parentheses.
For example, in free pascal:
{$mode fpc}
program bytecast;
uses sysutils;
type bytes = array[0..3] of byte;
var x : uint32 = $12345678; i : byte; b : bytes;
begin
b := bytes(x);
for i := 0 to 3 do Writeln('$',IntToHex(b[i],1))
end.
output:
$78
$56
$34
$12
Note that the "backwards" order here comes from the fact that I'm running on an x86 architecture, which uses a little-endian byte order.
If cross-platform portability is a concern, then you can either extract the bytes manually:
{ var r : uint32; ... }
for i := 0 to 3 do
begin
DivMod(x, $100, x, r); { needs 'uses math'. note: this destroys x! }
b[3-i] := r
end;
Now the bytes will be arranged in a more intuitive order, and the output of the earlier WriteLn loop becomes:
$12
$34
$56
$78
This will work on all platforms as well as any pascal dialect that prevents simple casting, at the cost of doing a little more work. (For another option, see the SwapEndian procedure and this FPC wiki page about cross platform code.)
