Substraction of next amount from previous amount.

Freaky

Hi Guys, can anyone help me on how I can get the differences between amounts.For example I have a variable called
amount
56
86

so i will like to have an answer of 86-56=30.

Thanks in advance.

jversusj

perhaps try giving your variable dimensions and make an array - then you'd have to add code to move the value of amount[1] to amount [2] on each iteration and then you could subtract [1] from [2]... does that get you started?

Freaky

Jversusj thanks for the help but I have no idea on how to use arrays in Nav. And my values on the variable "amount" is not just two they are numerous. Can you please assist more.

DenSter

MyAmount := 86 - 56;
MESSAGE('The amount is ' + FORMAT(MyAmount));

Freaky

Am Sorry if I did not give you a clear picture of what I meant this is how it is

Amount(decimal)
56.00
86.00
86.00
357.00
389.00
413.00
480.00
it continues


Results
0
86-56
86-86
357-86
389-357
413-357
480-413
it continues

So in each case I want to subtract the first value from the second value.

Thanks.

jversusj

i think you can do this, like i said, with an array.

create your variable and look at the properties. Set the dimensions property to 2 - this will let you keep 2 values in the variable at a time: variable[1] and varibable [2]. then you would do your processing. on your first record (you could be clever to code for the first time it happens versus all subsequent times), you would set variable[2] = your value. variable[1] would be 0. you could then do variable[2] - variable[1].

for all subsequent records you would first say variable[1] := variable[2], then you would set variable[2] equal your new value. you could then do variable[2] - variable[1] as before and get the difference.

so, using your example values:
56.00
86.00
86.00
357.00
389.00
413.00
480.00
etc.

the first time through, set variable[2] := 56.00. there is no previous entry because you just started, so difference := variable[2] - variable[1] would be 56.00. you could code a different formula if you really want the answer to be 0 (according to your example).
the next record would set variable[1] := 56.00 and variable[2] := 86.00, then difference := variable[2] - variable[1].

you would continue this through all records and always subtract the current from the previous.

MBerger

If it's on a form, then you could do the following :
- Add a Global Variable for your difference ( I'l call it Difference )
- Add a textbox to your tablebox, and add the Difference variable as its SourceExpression
- In the OnAfterGetRecord of the form, declare a variable of the same type as the main record ( let's call it PrevRec )

Prevrec.copy(rec) ;
if PrevRec.next(-1) <> 0 then
  //No previous Record found, assume 0 as previous value
  PrevRec.init ;

Difference := Rec.Value - Prevrec.value ;

Oh, and do consider that this will look strange if the records aren't sorted on the value you want to use, and filters might do strange things.

Belias

boolfirst := true
repeat
  actualvalue = tb.amount
  if BOOLfirst then begin
    BOOLfirst := false;
    result := 0;
  end else begin
    result := actualvalue - previousvalue;
  end;
  previousvalue := tb.amount;
until tb.next = 0;

***Not tested but should work

Freaky

Thanks guys for the help. I finally succeeded by using the array method jversusj posted.

jversusj

good to hear, although you should note that belias' code does the same thing, without messing with arrays. you would just set up two variables instead of 1 variable with multiple dimensions.

Belias

jversusj wrote:

good to hear, although you should note that belias' code does the same thing, without messing with arrays. you would just set up two variables instead of 1 variable with multiple dimensions.

but at least he learnt arrays...which is good!

Freaky

Belias I try using your code and when I try compiling it, it says THERE IS A SYNTAX ERROR.

Thanks

Belias

Freaky wrote:

Belias I try using your code and when I try compiling it, it says THERE IS A SYNTAX ERROR.

Thanks

Come on! don't blame me so much! (joking)...i forgot a semicolon...hmmm 2 semicolon, 1st and 3rd line...i didn't compile the code pefore posting it... 8)
....and put a findset or find('-') before the repeat :whistle:

Freaky

Thanks once more.