1. Calculator
Day 5 :
More Variables
Create It With
in cooperation with
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2. As you have seen in the last few days. We have been a heavy user of
variables. We have used local variables in the card and commands.
Since we only have one card, we have not had the chance to use
global variables.
We are almost done with our calculator, so we are going to do a quick
review of how we used variables to be extra sure everyone
understands. Then we are going to use variable to do a super cool
effect used by the calculator.
Hello World App
More
Variables
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3. Calculator App
The first variable we will cover is the local
card script variable. Again we are using
the numberPressed command, and we
can see the iNewNumber is used in 2 ways
1. Read - You can use it anywhere in
the card script for validation or
calculations.
2. Write - Sometime you will need to
set a new value to the variable
Local - Card
on mouseUp
numberPressed the label of target
end mouseUp
on numberPressed pNumPress
if lNewNumber = true then
---just set the Display to the number pressed
put pNumPress into field "display"
put false into lNewNumber --Not a new Num anymore
else
---add the pressed number to the display
put pNumPress after field "display"
End if
end numberPressed
You will also see a “l” in front, this will
indicate to you that it is a local card
variable. 3

4. Calculator App
Local - Command
on equalsPressed
--get out if no currentOperator, nothing to calculate
if lCurrentOperator is empty then exit equalsPressed
put field "display" into tCurrentValue
switch lCurrentOperator
case "/"
put lCurrentTotal / tCurrentValue into lCurrentTotal
break
case "x"
put lCurrentTotal * tCurrentValue into lCurrentTotal
break
case "-"
put lCurrentTotal - tCurrentValue into lCurrentTotal
break
case "+"
put lCurrentTotal + tCurrentValue into lCurrentTotal
break
end switch
put lCurrentTotal into field "display"
end equalsPressed
Next is the local command variable. When
you need to ONLY use the variable within
the current command
1. Write - You will need to set a new
value to the local variable so as to use
it.
2. Read - Then you will be able to use
the value in calculations, to control
logic flow or do validations.
You will also see a “t” in front, this will
indicate to you that it is a temporary or
local command variable. 4

5. Calculator App
The next variable we cover will be passed
parameter of commands. I have included
the numberPressed code.
1. when the user pressed a number,
that number is passed to the
numberPressed command as a
parameter.
2. LiveCode actually takes the
parameters, and presents them to
you as a local variable.
Parameters
on mouseUp
numberPressed the label of target
end mouseUp
on numberPressed pNumPress
if lNewNumber = true then
---just set the Display to the number pressed
put pNumPress into field "display"
put false into lNewNumber --Not a new Num anymore
else
---add the pressed number to the display
put pNumPress after field "display"
End if
end numberPressed
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You will also see a “p” in front, this will
indicate to you that it is a passed or
parameter variable. 5

6. Calculator App
Let see how to use local Command
variables to do something super cool. The
Calculator App will dynamically shrink the
font size of the display to fit in as much of
the number as it can.
1. With just a few numbers and lots of
extra space, the font size is 62. That
is our desired size.
2. But in order to allow more numbers in
the display, we need to shrink the
font size to a minimum of say 5.
Just One more Thing!
1 2
LiveCode is a VERY simple, yet powerful
language and we are going to show you
how to do this...
6

7. Calculator App
Let’s create a new command - textChanged.
Here will we will check and change the size of
the font in order to fit our number in the
display. To get this we use formattedWidth,
which give us what size the field should be
given the font size.
1. Add 2 lines to code that will give us the
formattedWidth vs width of the display.
2. Add the command to the bottom of the
numberPressed command. Click Apply,
run the App. After you have pressed
several numbers, you will start to see the
difference between the numbers.
formattedWidth
on textChanged
answer the formattedWidth of field "display"
answer the width of field "display"
end textChanged
on numberPressed pNumPress
...
--Allow the clearing of the Current value
--by setting the clear button to "C"
set the label of button "clear" to "C"
--Size Display to fit
textChanged
end numberPressed
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8. Calculator App
Start off by adding 2 local
variables that will hold our Min
text size and our Desired text size.
1. Notice that our variables
start with values. You can
change them if you wish.
2. Here is a little logic that will
check if the numbers have
become too large. If so, it
will decrease the font size of
the tDesiredTextSize by 10.
Setting the Min and Desired
Text Size Variables
on textChanged
local tMinTextSize = 5
local tDesiredTextSize = 62
---First, we use the formattedWidth property to see if the display is too large
if the formattedWidth of field "display" >= the width of field "display" then
put (tDesiredTextSize - 10) into tNewTextSize
set the textSize of field "display" to tNewTextSize
end if
end textChanged
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Problem: You can’t just put in any number like 10, you need the proper calculated size.
8

9. Calculator App
You can see how to utilize local
variables to hold calculated values
and make your code easier to
read and understand.
1. Use [effective textSize] to
get the MOST real size
possible
2. Then put whichever is bigger
tEffectiveSize or
tMinTextSize into tSize
3. Then get whichever is
smaller tSize or
tDesiredTextSize
Get the
tNewText Size
on textChanged
local tMinTextSize = 5
local tDesiredTextSize = 62
---First, we use the formattedWidth property to see if the display is too large
if the formattedWidth of field "display" >= the width of field "display" then
---Calculate the most effective size
put effective textSize of field "display" - 1 into tEffectiveSize
put max(tEffectiveSize, tMinTextSize) into tSize
put min(tSize, tDesiredTextSize) into tNewTextSize
set the textSize of field "display" to tNewTextSize
end if
end textChanged
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10. Calculator App Final Version
10
local tMinTextSize = 5
local tDesiredTextSize = 62
on textChanged
repeat while the formattedWidth of field "display" >= the width of field "display" - (item 1 of the margins of field "display" * 2)
--Calculate the most effective size
put the effective textSize of field "display" - 1 into tEffectiveSize
--Get the larger Min or tEffectiveSize
put max(tEffectiveSize, tMinTextSize) into tSize
--Get the smaller tSize or tDesiredTextSize
put min(tSize, tDesiredTextSize) into tNewTextSize
set the textSize of field "display" to tNewTextSize
if the textSize of field "display" = tMinTextSize then exit repeat
end repeat
repeat while the formattedWidth of field "display"< the width of field "display" - (item 1 of the margins of field "display" * 2)
--This line of code is similar in functionality except it enlarges the font size
set the textSize of field "display" to min (max ((the effective textSize of field "display" + 1), tMinTextSize) ,tDesiredTextSize)
if the textSize of field "display" = tDesiredTextSize then exit repeat
end repeat
end textChanged

11. Calculator App Compare
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local tMinTextSize = 5
local tDesiredTextSize = 62
on textChanged
repeat while the formattedWidth of field "display" >= the width of field "display" - (item 1 of the margins of field "display" * 2)
--Calculate the most effective size
put the effective textSize of field "display" - 1 into tEffectiveSize
--Get the larger Min or tEffectiveSize
put max(tEffectiveSize, tMinTextSize) into tSize
--Get the smaller tSize or tDesiredTextSize
put min(tSize, sDesiredTextSize) into tNewTextSize
set the textSize of field "display" to tNewTextSize
if the textSize of field "display" = tMinTextSize then exit repeat
end repeat
repeat while the formattedWidth of field "display"< the width of field "display" - (item 1 of the margins of field "display" * 2)
--This line of code is similar in functionality except it enlarges the font size
set the textSize of field "display" to min (max ((the effective textSize of field "display" + 1), sMinTextSize),tDesiredTextSize)
if the textSize of field "display" = tDesiredTextSize then exit repeat
end repeat
end textChanged

12. If you wish to learn more… Visit LiveCode
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More Variables
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Calculator App
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