Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

how to calculate

Posted on 2007-03-22
16
Medium Priority
?
637 Views
Last Modified: 2008-01-09
I would like to do some calculations on my form.
I have dbtext,currencyedit's and dbedit's.
Can you give me example how to calculate using these?
example:
I have a dbtext that gets a value from database.
Now I want that value to divide from a value in editbox
so a currency edit gives me the right sum..
just learning...
0
Comment
Question by:Vrtnar
[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
  • 8
  • 7
16 Comments
 
LVL 21

Expert Comment

by:ziolko
ID: 18770593
var a, b: Integer;
      c: Double;

if TryStrToInt(dbtext.caption, a) and tryToInt(dbedit.text, b) then
  c := b / a;

ziolko.
0
 

Author Comment

by:Vrtnar
ID: 18770706
dont understand a thing...
I tried --
var a, b: Integer;
      c: Double;
begin
if StrToInt(dbedit1.text, a) and StrToInt(edit14.text, b) then
currencyedit37.value := b / a;

and it dont work...please fro a nice explanation as I just learn
0
 

Author Comment

by:Vrtnar
ID: 18770769
if TryStrToInt(dbedit1.Text,a) and TryStrToInt(edit14.text,b) then
currencyedit37.value:= a / b;
does not work either...
0
VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

 
LVL 21

Expert Comment

by:ziolko
ID: 18770798
TDBEdit has property called Text
TDBEdit has property called Caption
both properties are of type string which means they can contain literlas
so if you want to do any mth calculation you need to convert them

there are 3 most commonly used functions:
1. StrToInt() this func will throw exception if it's not possible to convert
sample

procedure S1;
var s: string;
      i: Integer;
begin
  s := 'hello world';
  try
    StrToInt(s, i);
  except
    ShowMessage('cannot convert hello world to integer value');
  end;
end;

2. TryStrToInt() <- no error will be thrown

procedure S2;
var s: string;
      i: Integer;
begin
  s := 'hello world';
  if not TryStrToInt(s, i) then
    ShowMessage('cannot convert hello world to integer value');
end;

3. Val() <- no error will be thrown

procedure S3;
var s: string;
      i: Integer;
      val: Integer;
begin
  s := 'hello world';
  Val(s, i, code);
  if code <> 0 then
    ShowMessage('cannot convert hello world to integer value');
end;



ziolko.
0
 
LVL 21

Expert Comment

by:ziolko
ID: 18770821
what kind of values you have in edits?

ziolko.
0
 

Author Comment

by:Vrtnar
ID: 18770836
dbedit has no caption value but text.
in your 1st example to what do I assign   'c' ??
My 'c' should be a currency edit...
0
 

Author Comment

by:Vrtnar
ID: 18770837
in edits I have numbers only...
0
 
LVL 21

Expert Comment

by:ziolko
ID: 18770918
my mistake TBText has Caption...

this should work unless you have floating point values in edit or text
if TryStrToInt(dbedit1.Text,a) and TryStrToInt(edit14.text,b) then
currencyedit37.value:= a / b;

if you have floating point use TryStrToFloat()

ziolko.
0
 

Author Comment

by:Vrtnar
ID: 18771054
dbedit1 is currency value in the database.
in edit14 i type in (freehand) number values.
I tried (on exit of the edit14):
procedure TPostavke.Edit14Exit(Sender: TObject);
var a, b: Integer;
      c: Double;
begin
if TryStrToInt(dbedit1.Text,a) and TryStrToInt(edit14.text,b) then
currencyedit37.value:= a / b;
end;
It does not work..
If i substitute TryStrToInt with TryStrToFloat i get :
[Error] Unit3.pas(255): There is no overloaded version of 'TryStrToFloat' that can be called with these arguments

You see I have a value of '584,65 €' in my dbedit1.
Now I want to type (example number 2 in my editbox) and when I leave the edit my currency displays
292,325...
0
 
LVL 21

Accepted Solution

by:
ziolko earned 500 total points
ID: 18771104
ok,

procedure TPostavke.Edit14Exit(Sender: TObject);
var a: Currency;
      b: Double;
begin
  if TryStrToCurr(dbedit1.Text,a) and TryStrToInt(edit14.text,b) then
    currencyedit37.value:= a / b;
end;

ziolko.
0
 

Author Comment

by:Vrtnar
ID: 18771208
procedure TPostavke.Edit14Change(Sender: TObject);
var a: Currency;
     b: double;
begin
if TryStrToCurr(dbedit1.Text,a) and TryStrToInt(edit14.text,b) then
    currencyedit37.value:= a / b;
end

I get :
[Error] Unit3.pas(256): Types of actual and formal var parameters must be identical
0
 
LVL 10

Expert Comment

by:dinilud
ID: 18771616
instead of TryStrToInt use TryStrToFloat
0
 
LVL 21

Expert Comment

by:ziolko
ID: 18771651
what the ...??

i've already posted:
if TryStrToCurr(dbedit1.Text,a) and TryStrToFloat(edit14.text,b) then
    currencyedit37.value:= a / b;

where did it go??

ziolko.
0
 

Author Comment

by:Vrtnar
ID: 18773093
Dont seem to work...both ways...
0
 

Author Comment

by:Vrtnar
ID: 18773543
I think i have figured what is the mistake here..
a queery that is the info provider for dbedit1 has the field
marked as 'currency' (it is currency in the database however)
But when I remove the field type as 'currency' in the
field rooster and set it to currency false the code :
var a: Currency;
      b: integer;
begin
if TryStrToCurr(dbedit1.Text,a) and TryStrToInt(edit12.text,b) then
    currencyedit37.value:= a / b;
works !
is this ok ??
0
 
LVL 21

Expert Comment

by:ziolko
ID: 18778162
if it works it's ok:)

ziolko.
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone 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

Objective: - This article will help user in how to convert their numeric value become words. How to use 1. You can copy this code in your Unit as function 2. than you can perform your function by type this code The Code   (CODE) The Im…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
Add bar graphs to Access queries using Unicode block characters. Graphs appear on every record in the color you want. Give life to numbers. Hopes this gives you ideas on visualizing your data in new ways ~ Create a calculated field in a query: …
In this video, Percona Solution Engineer Rick Golba discuss how (and why) you implement high availability in a database environment. To discuss how Percona Consulting can help with your design and architecture needs for your database and infrastr…
Suggested Courses

664 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