stream - Delphi ReadStreamStr, WriteStreamStr implementation check -

i'm using these implementations found on post on so. when reading string in sometimes, readstreamstr puts in characters string. i'm posting implementation here have checked , approved, , if there fault, corrected.

function readstreamstr(stream: tstream): string; { returns string stream } var   lenstr: integer; begin   result := '';   { length of string }   lenstr := readstreamint(stream);   { set string memory }   setlength(result, lenstr);   { read characters }   stream.read(result[1], lenstr); end;  procedure writestreamstr(stream: tstream; str: string); { writes string stream } var   strlen: integer; begin   { length of string }   strlen := bytelength(str);   { write length of string }   writestreamint(stream, strlen);   if strlen > 0     { write characters }     stream.write(str[1], strlen); end; 

thank you.

the integer written in front of characters number of bytes, readstreamstr() interpreting number of characters instead. in d2007 , earlier, string ansi, works fine. in d2009 , later, string unicode, not work. assuming using d2009+, means readstreamstr() allocating twice memory should be, filling in half of it, leave other half uninitialized. not taking sizeof(char) account when reading (but bytelength() when writing).

try this:

function readstreamstr(stream: tstream): string; { returns string stream } var   lenstr: integer;   leftover: array[0..sizeof(char)-1] of byte; begin   result := '';   { length of string }   lenstr := readstreamint(stream);   { set string memory }   setlength(result, lenstr div sizeof(char));   if lenstr > 0 begin     { read characters }     stream.readbuffer(result[1], lenstr);     { in case length not }     lenstr := lenstr mod sizeof(char);     if lenstr > 0       stream.readbuffer(leftover[0], lenstr);   end; end; 

alternatively:

function readstreamstr(stream: tstream): string; { returns string stream } var   lenstr: integer;   buf: tbytes; begin   result := '';   { length of string }   lenstr := readstreamint(stream);   if lenstr > 0 begin     { memory }     setlength(buf, lenstr);     { read characters }     stream.readbuffer(buf[1], lenstr);     { convert string }     result := tencoding.unicode.getstring(buf);   end; end; 

either way, keep in mind if stream data written in d2007 or earlier, read in d2009 or later, code not work as-is. have go tbytes approach, use more appropriate tencoding decoding, such tencoding.default.

personally, have opted instead read/write strings utf-8 beginning:

function readstreamstr(stream: tstream): utf8string; { returns string stream } var   lenstr: integer; begin   result := '';   { length of string }   lenstr := readstreamint(stream);   { set string memory }   setlength(result, lenstr);   if lenstr > 0     { read characters }     stream.read(pansichar(result)^, lenstr); end;  procedure writestreamstr(stream: tstream; const str: utf8tring); { writes string stream } var   strlen: integer; begin   { length of string }   strlen := length(str);   { write length of string }   writestreamint(stream, strlen);   if strlen > 0     { write characters }     stream.write(pansichar(str)^, strlen); end;