CREATING THE abcDB CALCULATOR APPLICATION

First, let's create a new database.  Call it Calculator.

Now that we've got an 'empty' database, let's get started.  Let's create a new form.  When prompted, call this form CALCULATOR.  Do not base it on any table.

Add the following controls:

CONTROL TYPE               Caption                                 TAG

TEXTBOX                                                                       DISPLAY

LABEL                                  Root                                     lblRoot

LABEL                                  1/x                                       lblFraction

LABEL                                  M+                                       lblMemPlus

LABEL                                  <-                                         lblBackspace

LABEL                                  %                                          lblPercent

LABEL                                  MC                                       lblMemClear

LABEL                                  MR                                       lblMemRecall

LABEL                                  Clear                                     lblClear

LABEL                                  1                                           lblOne

LABEL                                  2                                           lblTwo

LABEL                                  3                                           lblThree

LABEL                                  4                                           lblFour

LABEL                                  5                                           lblFive

LABEL                                  6                                           lblSix

LABEL                                  7                                           lblSeven

LABEL                                  8                                           lblEight

LABEL                                  9                                           lblNine

LABEL                                  0                                           lblZero

LABEL                                  .                                            lblDecimal

LABEL                                  =                                          lblEquals

LABEL                                  +                                          lblPlus

LABEL                                  -                                            lblMinus

LABEL                                  *                                           lblMultiply

LABEL                                  /                                           lblDivide

Now, let’s add the code necessary to make our ‘keys’ work.  We’ll program the 0-9 keys, and the + - * / . keys.

CONTROL                          Code to place in ON CLICK event.

lblOne                                  SETVALUE(~DISPLAY~//~DISPLAY~“1”)

lblTwo                                  SETVALUE(~DISPLAY~//~DISPLAY~“2”)

lblThree                                SETVALUE(~DISPLAY~//~DISPLAY~“3”)

lblFour                                 SETVALUE(~DISPLAY~//~DISPLAY~“4”)

lblFive                                  SETVALUE(~DISPLAY~//~DISPLAY~“5”)

lblSix                                    SETVALUE(~DISPLAY~//~DISPLAY~“6”)

lblSeven                                SETVALUE(~DISPLAY~//~DISPLAY~“7”)

lblEight                                 SETVALUE(~DISPLAY~//~DISPLAY~“8”)

lblNine                                 SETVALUE(~DISPLAY~//~DISPLAY~“9”)

lblZero                                 SETVALUE(~DISPLAY~//~DISPLAY~“0”)

lblPlus                                  SETVALUE(~DISPLAY~//~DISPLAY~“+”)

lblMinus                               SETVALUE(~DISPLAY~//~DISPLAY~“-”)

lblMultiply                            SETVALUE(~DISPLAY~//~DISPLAY~“*”)

lblDivide                               SETVALUE(~DISPLAY~//~DISPLAY~“/”)

lblDecimal                            SETVALUE(~DISPLAY~//~DISPLAY~“.”)

Basically, the SETVALUE command in each label will take the current value contained in the DISPLAY textbox, and will append the appropriate character.

If we wanted to get REAL fancy, we could play a different sound when each key is tapped by adding something like this in each keys ONCLICK event:

PLAYSOUND(“/My Documents/MySound.wav”//1)

But I’ll leave that up to you. 

For now, let’s SAVE our form (use the name CALC) and we’ll test it out.

Cool!  It works!  We can enter numbers and calculations. 

Unfortunately, pressing the “=” button doesn’t do anything, so our calculator is still pretty much useless!  So let’s fix this now.

In the ON CLICK event of the lblEquals control, enter the following code:

SETVALUE(~DISPLAY~//eval(~DISPLAY~))

This will evaluate the currently displayed expression and store the result in our DISPLAY textbox.

Try it out and you’ll see that it works.

But for now, let’s get our other function keys working on our calculator…

Enter the following code in the controls specified:

CONTROL                             Code to place in ON CLICK event.

lblRoot                        SETMEM(ROOT//SQR(~DISPLAY~))

             SETVALUE(~DISPLAY~//<!ROOT!>)

lblPercent                     SETMEM(PERCENT//~DISPLAY~/100)

             SETVALUE(~DISPLAY~//<!PERCENT!>)

lblFraction                   SETMEM(FRACTION//1/~DISPLAY~)

             SETVALUE(~DISPLAY~//<!FRACTION!>)

lblMemClear              SETMEM(MEMORY//0)

lblMemAdd               SETMEM(MEMORY//<!MEMORY!> + ~DISPLAY~)

lblMemRecall             SETVALUE(~DISPLAY~//<!MEMORY!>)

lblBackspace     SETMEM(LENGTH//LEN(~DISPLAY~))
         SETMEM(A//<!length!>-1)
         SETVALUE(~DISPLAY~//LEFT(~DISPLAY~,<!A!>))

lblClear                       SETVALUE(~DISPLAY~//)

Once you’ve saved these changes and run the program, you should be able to use our calculator to perform calculations.  This screen shot shows the results of entering 19.89 * 5:

Even our memory keys work! 

What else could we do to make it better?  Well, you may want to set the NAVIGATIONMENU property of the form to NO.  That we we won't see the unnecessary menu at the top of the screen.  Again, I'll leave that up to you.

In any case, you can see from this little exercise some more evidence that abcDB Database truly is a powerful ‘mobile’ programming tool!