Solved

how to separate the float number from string

Posted on 2008-10-30
13
353 Views
Last Modified: 2010-04-05
Hello Guys,
Can you tell me how can I receive only a float number from the string. For example:
string -  252.676g or f466.422d
BR
Vaalar
0
Comment
Question by:Vaalar
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 7
  • 3
  • 3
13 Comments
 
LVL 37

Accepted Solution

by:
Geert Gruwez earned 400 total points
ID: 22840148
use the Val function

function ConvertFloat(aText: string): Double;
var S: string;
  I, aCode: Integer;
begin
  // First delete all non number characters
  I := 1;
  while (I < Length(aText)) and not (aText[I] in ['-','+',DecimalSeparator,ThousandSeparator,'0'..'9']) do
    Inc(I);
  // Convert text to float
  Val(Copy(Atext, I, Length(aText)), Result, aCode);
end;
0
 
LVL 15

Assisted Solution

by:mikelittlewood
mikelittlewood earned 100 total points
ID: 22840218
This assumes only one number in there
I use the tryTo function instead of the val

function TForm1.returnFloat(const s: string): double;
var
   i: integer;
   temp: string;
begin
   result := 0;
   temp := '';
   for i := 0 to length( s) do
      if s[i] in ['0'..'9', DecimalSeparator,ThousandSeparator, '+', '-'] then
         temp := temp + s[i];

   if temp <> '' then
      tryStrToFloat( temp, result)
end;
0
 
LVL 15

Expert Comment

by:mikelittlewood
ID: 22840268
Geert_Gruwez, your code doesnt take into account if there is a non numerical character at the end of the string.
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 22840278
no need the Val does this
0
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 22840294
the aCode will show the location of the problem

maybe Vaalar can evaluate further what he wants to happen ?
0
 
LVL 15

Expert Comment

by:mikelittlewood
ID: 22840334
In fact it might be better to make sure you never continue past the first number that is found

function TForm1.returnFloat(const s: string): double;
var
   i, startPos, endPos: integer;
begin
   result := 0;

   startPos := 1;
   while ( not ( s[ startPos] in ['0'..'9', DecimalSeparator,ThousandSeparator, '+', '-'])) and
         ( startPos <= length( s)) do
      inc( startPos);

   endPos := startPos;
   while ( s[ endPos] in ['0'..'9', DecimalSeparator,ThousandSeparator, '+', '-']) and
         ( endPos <= length( s)) do
      inc( endPos);

   if endPos >= startPos then
      tryStrToFloat( copy( s, startPos, endPos - startPos), result)
end;
0
 

Author Comment

by:Vaalar
ID: 22840744
Thx for your help.
I have tested your ideas and it solves  but if i have for example 244e.322 i get 244 afer using Gerts solution. I need to receive 244.322.
The same problem comes out in Mikes solution.
0
 

Author Comment

by:Vaalar
ID: 22840760
Thx for your help.
I have tested your ideas and it solves some problems  but if i have for example 244e.322 i get 244 afer using Gerts solution. I need to receive 244.322.
The same problem comes out in Mikes solution.
0
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 22840976
you could first strip all non numerals:

function ConvertFloat(aText: string): Double;
var S: string;
  I, aCode: Integer;
begin
  // First delete all non number characters
  I := 1;
  s := '';
  while (I <= Length(aText)) and (aText[I] in ['-','+',DecimalSeparator,ThousandSeparator,'0'..'9']) do
  begin
    s := s + aText[I];
    Inc(I);
  end;
  // Convert text to float
  Val(S, Result, aCode);
end;
0
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 22841015
this will never solve all problems
it will get the first number possible

but to resolve this you'll need to specify some rules:

aText := 'abc123.def456-789+1023xxx';

Value to string = '123.456-789+1023';
0
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 22841022
woops slight mistake

function ConvertFloat(aText: string): Double;
var S: string;
  I, aCode: Integer;
begin
  // First delete all non number characters
  I := 1;
  s := '';
  while (I <= Length(aText)) do
  begin
    if (aText[I] in ['-','+',DecimalSeparator,ThousandSeparator,'0'..'9']) then
      s := s + aText[I];
    Inc(I);
  end;
  // Convert text to float
  Val(S, Result, aCode);
end;
0
 
LVL 37

Expert Comment

by:Geert Gruwez
ID: 22841052
or try StrToFloatDef

Result := StrToFloatDef(S, 0);
0
 

Author Comment

by:Vaalar
ID: 22841236
Thank you very much Geert,
and thx also to Mike
BR
Vaalar
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The uses clause is one of those things that just tends to grow and grow. Most of the time this is in the main form, as it's from this form that all others are called. If you have a big application (including many forms), the uses clause in the in…
Introduction Raise your hands if you were as upset with FireMonkey as I was when I discovered that there was no TListview.  I use TListView in almost all of my applications I've written, and I was not going to compromise by resorting to TStringGrid…
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…
In this video, viewers are given an introduction to using the Windows 10 Snipping Tool, how to quickly locate it when it's needed and also how make it always available with a single click of a mouse button, by pinning it to the Desktop Task Bar. Int…

696 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question