Simple and weird question about accuracy! !! !! Everyone help!

rosbicn

How to achieve s always display 8.07000000000000028? ? ? ? ? ?

面面爱面面

My knowledge is not professional enough, so I can only say an estimate:

I guess it is because the number of your # exceeds the accuracy range of real numbers. In fact, I estimate that 8.07 is displayed as 8.000000000000028, which is an error in itself. Please take a look at my reply above. The correct result should be displayed as 8.07 or 8.070000000000000

Then you press my code and replace var a: double; with var a: Extended; try, can you add a lot#

rosbicn

Thank you面面爱面面, but if I wish
var
  a:double;
  s:string;
  vADOConnection:Variant;
begin
  a := 8.07;
  s := formatfloat('#.################',a);//s display 8.07000000000000028
  vADOConnection := CreateOleObject('ADODB.Connection');
  vADOConnection.ConnectionString :='Driver={Firebird/InterBase(r) driver};pwd=masterkey;Uid=SYSDBA;database=C:\123.GDB';
  try
    vADOConnection.Open;
  Except
  end;
  a := 8.07;
  s := formatfloat('#.################',a);//s display 8.07
end;

The place where 8.07 is displayed also displays 8.07000000000000028, which means that even if it is wrong, it is also wrong!

I personally understand that vADOConnection.Open calls the MS library file, so the number after the effective digits is directly deleted. Is there any good way to not delete it?