?
Solved

how to separate the float number from string

Posted on 2008-10-30
13
Medium Priority
?
357 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 38

Accepted Solution

by:
Geert Gruwez earned 1600 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 400 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
Industry Leaders: 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 38

Expert Comment

by:Geert Gruwez
ID: 22840278
no need the Val does this
0
 
LVL 38

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 38

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 38

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 38

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 38

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

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

Introduction The parallel port is a very commonly known port, it was widely used to connect a printer to the PC, if you look at the back of your computer, for those who don't have newer computers, there will be a port with 25 pins and a small print…
In my programming career I have only very rarely run into situations where operator overloading would be of any use in my work.  Normally those situations involved math with either overly large numbers (hundreds of thousands of digits or accuracy re…
Michael from AdRem Software outlines event notifications and Automatic Corrective Actions in network monitoring. Automatic Corrective Actions are scripts, which can automatically run upon discovery of a certain undesirable condition in your network.…
In this video, Percona Solutions Engineer Barrett Chambers discusses some of the basic syntax differences between MySQL and MongoDB. To learn more check out our webinar on MongoDB administration for MySQL DBA: https://www.percona.com/resources/we…
Suggested Courses
Course of the Month13 days, 12 hours left to enroll

801 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