On 2023-12-19 12:36, James Richters via fpc-pascal wrote:
Hello James,
I keep getting bit by using STRING variables then trying to store more
than 255 characters.
My typical way to fix this is to just change it to an ANSISTRING.
I'm wondering if there is any reason not to do this the other way
around and just go through
.
.
You may be surprised, but FPC (and even earlier also Delphi) provides
you with multiple ways allowing you to use variables declared as
"string" without length limits (i.e. using type ansistring or
unicodestring underneath). There are compiler directives {$H+} and
{$UNICODESTRINGS} doing exactly that, and there are also modes {$MODE
DELPHI} and {$MODE DELPHIUNICODE} which (among others) trigger the
previously mentioned compiler directives (the difference is that the
modes have wider impact, not only the underlying type used for
variables, parameters, etc., of type string).
In order to answer you question about potential reasons for not using
ansistring or unicodestring for everything, it's useful to understand
the associated differences:
1) Ansistring and Unicodestring are reference counted. This brings some
computational overhead potentially impacting performance - this may not
be important in many cases, but there are also cases for which this may
be very important.
2) Ansistring and Unicodestring are technically pointers to structures
allocated on the heap rather than directly storing the string itself
with preallocated number of characters. There are scenarios for which
this difference is important (e.g. when interfacing with operating
system API calls or 3rd party code in general).
3) There are some other smaller differences impacting compatibility with
code designed to work with type shortstring (e.g. related to used
character sets etc.).
Tomas
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