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how can i make a float upto 6 decimal places?

Posted on 2004-09-28
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Last Modified: 2010-08-05
My problem is when i assign a value with my currency:float;

currency:=1.123456;

the currency variable will only hold upto 4 decimal places even if i already set the "CurrencyDecimals=6"
the currency above will automatically change the value with "1.1235".

anybody can help?

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Question by:girlswants_me
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LVL 30

Expert Comment

by:third
Comment Utility
try this,

Currency := StrToFloat(FormatFloat('0.000000', 1.123456));
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Author Comment

by:girlswants_me
Comment Utility
Im using this DB float

procedure TfDataModule.CreateTable_CurrencyExchangeTable(NameFile: string);
var
 DatabaseDirectory:string;
begin
  with TTable.Create(Application) do
  begin
    Active := False;
    DatabaseName := fMain.p_sDatabasePath;
    TableName := NameFile;
    TableType := ttDBase;
    with FieldDefs do
    begin
      Clear;
      Add('INDEXNO'         , ftString , 15, false);
      Add('CURRDESC'        , ftString ,  5, false);
      Add('DISPCURR'        , ftString ,  1, false);
      Add('EXCVALUE'        , ftfloat  ,  0, false);
    end;
    CreateTable;
    Free;
  end;
end;

Now when the 1.1234567 will be assigned to the field "EXCVALUE", when you browse the ""EXCVALUE" field again the number shown will already 1.1235.

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LVL 17

Expert Comment

by:Wim ten Brink
Comment Utility
The currency type isn't a true float type. It's an Integer type where the numbers are just shifted 4 positions. Basically, it's an "Int64 div 1000" type. Thus you can NEVER get more than 4 decimals in a currency type, just like you cannot get any decimal in an integer type.

The currency type is actually just a fixed-decimal type. Use Extended instead if you need more decimals and remember, if it's ever gets converted to currency and back again, you'll lose 2 digits. There is no cure for this, though. Except for not using currency at all.
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Expert Comment

by:Wim ten Brink
Comment Utility
Thus: Use Extended, not currency!
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LVL 17

Expert Comment

by:geobul
Comment Utility
Hi,

1. Use AddFieldDef method instead of Add
2. Use ftBCD instead of ftFloat
3. Set Precision property of the field to the desired size
4. Set Size property to the desired number of digits following the decimal point, i.e. 6 in your case

Regards, Geo
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Author Comment

by:girlswants_me
Comment Utility
geobul,

Can you please write this in codes..... What i am using now is saving it as string and when i want to use that decimal number i just turn it to strtofloat(decimalString)...

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LVL 17

Accepted Solution

by:
geobul earned 50 total points
Comment Utility
Sure:

procedure TfDataModule.CreateTable_CurrencyExchangeTable(NameFile: string);
var
 DatabaseDirectory:string;
begin
  with TTable.Create(Application) do
  begin
    Active := False;
    DatabaseName := fMain.p_sDatabasePath;
    TableName := NameFile;
    TableType := ttDBase;
    with FieldDefs do begin
      Clear;
      Add('INDEXNO'         , ftString , 15, false);
      Add('CURRDESC'        , ftString ,  5, false);
      Add('DISPCURR'        , ftString ,  1, false);
      with AddFieldDef do begin
        Name := 'EXCVALUE';
        DataType := ftBCD;
        Precision := 15;
        Size := 6;
        Required := false;
      end;
    end;
    CreateTable;
    Free;
  end;
end;
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LVL 17

Expert Comment

by:Wim ten Brink
Comment Utility
@geobul, I've checked something. The TBCDField type uses the currency type for it's Value property. And no matter what you try, the currency type will NEVER hold more than 4 decimals after the dot. This might be a minor flaw. A TFloatField would be better. The use of ftFloat would be better, don't you agree? Because ftFloat uses a Double type for the value.

But the flaw might actually be in the DBase table that is used. If in this table, the precision of the field is set to 4 positions then you'll never get 6 positions in it...

@girlswants_me, can you check the table definition of your DBase table, to make sure it uses 6 decimals after the dot? You can easily do this from the Database Desktop. If the field itself doesn't hold more than 4 positions then that's the problem...

And avoid the currency type. It's not usable if you want more than a precision of 4.
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LVL 17

Expert Comment

by:geobul
Comment Utility
Well, it's been a long time ago when I used BDE for the last time. As far as I remember using ftBCD was the way for making DBase field of type 'Numeric' and with fixed length after the point (that field in my example above should become 'N 15 6' in Database Desktop - in my D5 at least). Thinking more now, ftFloat should be capable of storing 6 digits and more also.

So, perhaps the problem is not in the table layout but in the type of the var used for reading (as Alex already pointed out) and/or in the visualization method being used. For the last I'd suggest Format function:

var currency: float; // or double/extended
begin
  ... // open the table and position it to a record
  currency := Table1.FieldByName('EXCVALUE').AsFloat;
  ShowMessage(Format('%15.6n',[currency])); // you must get '1.123456' here if you had that value in the table.

Regards, Geo
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LVL 17

Expert Comment

by:Wim ten Brink
Comment Utility
@geobul, when I read the currency:float part of the post, it just suddenly struck me. girlswants_me is using a VARIABLE called currency, of type float. He is not using the currency TYPE. And I remembered that with DBase, you have to specify the number of decimal places of any numeric field. Thus, this is why his table itself has the flaw. I think EXCVALUE is probably defined as a Float field with only 4 digits after the dot. Which means the flaw is in his table, which can be solved by making the EXCVALUE slightly bigger. (Requires a restructure.)

I dare to bet 500 points that this is a table structure issue. :-)
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LVL 17

Expert Comment

by:geobul
Comment Utility
@Workshop_Alex, I thought it was a db problem in the beginning too. That's why I posted comments about 'improving' CreateTable code. But reconsidered my opinion later on. I'm accepting your bet just for fun :-)

@girlswants_me, we are waiting your response with great interest.
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LVL 17

Expert Comment

by:geobul
Comment Utility
Hey, there is no FLOAT type for variables. What type are you using actually?
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LVL 17

Expert Comment

by:Wim ten Brink
Comment Utility
Either Double or Extended I guess. Both types are referred as FLOAT types, but the Extended type is 2 bytes bigger. With Delphi, the FLOAT type in databases is converted to the Double type.
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Author Comment

by:girlswants_me
Comment Utility
Hi everyone,

Sorry for this late answer. Actually i tried geobul's code and it works fine for me. Actually, i am using the "currency" as type ftString, and when ever i will get the value of my "currency" i will just make it as a float ex. curr = strtofloat(thetable.fieldbyname('currency').asstring)

thank you very much for all your support and help
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LVL 17

Expert Comment

by:geobul
Comment Utility
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