[ SOLVED ] length in chars needed to represent float in 32bit program
lazarus / 62-General

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superc · 2021-09-06 06:57

Hello,

what is the maximum length in chars needed to represent float into
string in 32 bit program?

Thanks in advance.

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Bart · 2021-09-06 07:55

That depends on the type of float: single, double, extended and the
platform (on some platforms extendes is just an alias for double).

Bart

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winni · 2021-09-06 08:13

Hi!

Have a look at

https://www.freepascal.org/docs-html/ref/refsu5.html

Winni

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BobDog · 2021-09-06 11:05

I can produce a perfect cast from double to ansistring.
(windows)
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i    uses 
 sysutils; function sprintf(s:pchar;mask:pchar):integer; cdecl;
varargs; external 'msvcrt.dll' name 'sprintf';  function
dbl2str(d:double):ansistring;var ans:ansistring;var
i:int32;beginsetlength(ans,32);FillChar(ans[1],32,#0); 
sprintf(@ans[1],'%.30f',d);  if (pos('.',ans) <>0) then  begin  for
i:=length(ans) downto 1 do   begin   if (ans[i]<>'0')  then break;   
if (ans[i]='0') then ans[i]:=#32;   end;  end ; 
exit(trim(ans));end;   var i,tmp:int32;var d,v:double;var
s:ansistring; begin for i:=1 to 5000 do begin 
 d:=(random*100)-(random*100);   s:= dbl2str(d);   val(s,v,tmp);   if
(v<>d) then writeln('error');   writeln('''',s,'''','  ',d);  end; 
writeln ('Press return to end'); readln; end.

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winni · 2021-09-06 12:24

Hi!

Look how FloatToStr works:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i showmessage
(FloatToStr(3.98765432109876543210)); Because there are  too many
digits the string shows only

3.98765432109877

Next example:Code: Pascal  [Select][+][-]window.onload =
function(){var x1 = document.getElementById("main_content_section");
if (x1) { var x = document.getElementsByClassName("geshi");for (var i
= 0; i  showmessage (FloatToStr(12345678901234567890.0));  
Because of too many digits the result is shown in the scientzific
notification

123456789012346E19

Winni