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How to convert a string to double

Posted on 1998-07-13
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Last Modified: 2010-05-18
i have a problem in converting a string from a PChar type to a double type? may you suggest a method to perform this easy task?
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Question by:smile_tbw
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10 Comments
 

Expert Comment

by:bengore
ID: 1357838
Try this:
var d:double;
    p:PChar;
begin
  d:=1.09;
  p:=PChar(@d);
end;

If you want convert a string to an UNICODE string (array of double byte char), then use
WideCharToMultiByte() and MultiByteToWideChar().

The WideCharToMultiByte function maps a wide-character string to a new character string. The new character string is not necessarily from a multibyte character set.

The MultiByteToWideChar function maps a character string to a wide-character (Unicode) string. The character string mapped by this function is not necessarily from a multibyte character set.
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LVL 8

Expert Comment

by:ZifNab
ID: 1357839
Hi smile_tbw,

 ?

Is this what you mean :

var TextPChar : PChar;
    Number : Double;
begin
 TextPChar := '5000,4';
 Number := StrToFloat(TextPChar);
end;

Zif.
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LVL 8

Expert Comment

by:ZifNab
ID: 1357840
Well, I was too late again... but bengore, isn't the answer supposed to be the other way?
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Author Comment

by:smile_tbw
ID: 1357841
I think the answer propose by ZifNab is the answer i want but not by bengore. BUT how to give the point to ZifNab instead of bengore?? Please help!!

In addition, my string is ended with a CR($D) and LF(£A). How to avoid it because it can't convert by using StrToFloat. Thanks.
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Author Comment

by:smile_tbw
ID: 1357842
I'm sorry, bengore. you answer seem to be reversed to my question.
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LVL 8

Accepted Solution

by:
ZifNab earned 60 total points
ID: 1357843
Hi smile_tbw. Just remove the two last chars from the string, use copy or delete to do it :

var TextPChar : PChar;
           Number : Double;
       begin
        TextPChar := '5000,4'+char($D)+char($A);
        showmessage('with CR and LF :'+TextPChar);
        showmessage('without : '+Copy(TextPChar,1,Length(TextPChar)-2));
        Number := StrToFloat(Copy(TextPChar,1,Length(TextPChar)-2));
        ShowMessage('GoodLuck!');
       end;

Regards, Zif.
Have a nice day.
0
 

Author Comment

by:smile_tbw
ID: 1357844
hi Zif,

In addition my string is ended with a CR($D) and LF($A). How to avoid it because it can't convert by using StrToFloat

Thnaks.

0
 

Author Comment

by:smile_tbw
ID: 1357845
hey, Zif,
sorry about the point was accidentally reduced to 6. Actually i want to increase it to 60. BUT.. .. . .. Sorry again. Hope you don't mind.

Thank you very much
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LVL 8

Expert Comment

by:ZifNab
ID: 1357846
Hi smile_tbw,

look at answer I gave you... I remove the two last chars (namely CR and LF) from the string before I use StrToFloat.

this is the function : Copy(TextPChar,1,Length(TextPChar)-2)

Ok,I just copy a part of the total string (all the char, without the last 2), but maybe it's also possible with other functions, e.g. Delete ...

The beauty of the copy is that you can still use the total string for futher processing.

Just copy my example and you got it.

Zif.
0
 
LVL 8

Expert Comment

by:ZifNab
ID: 1357847
Smile_tbw,

nope don't mind, only don't know if you can reduce the points.

->hi Zif,

       In addition my string is ended with a CR($D) and LF($A). How to avoid it because it can't convert by using StrToFloat

       Thnaks.

I think you found it in the answer I gave you :-), otherwise you wouldn't accept my answer so soon.

ZiF.

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