Can't declare a global variable inside IF statement (Pine Script) - if-statement

Question

I am new to Pine Script and have some problem declaring a variable inside an if and use it inside another if...
In the first if statement, I tried to get the "close price" of the long signal (LongPrice).
And in the second if, I tried to get the "close price" of the short signal (ShortPrice) and subtract it from "LongPrice".
But the value of "LongPrice" not changed outside its own if statement!
From what I understand this means that the variable is not valid outside of the if statement. Is there a way to change this?
LongPrice = 0
ShortPrice = 0
if mmeLong
LongPrice = close // Get the Long signal's close price
label.new(bar_index, na, tostring(LongPrice),
color=color.green,
textcolor=color.white,
style=label.style_labelup, yloc=yloc.belowbar)
if mmeShort
ShortPrice = close - LongPrice // Get the Short signal's close price and minus it with the last Long close price.
label.new(bar_index, na, tostring(ShortPrice),
color=color.red,
textcolor=color.white,
style=label.style_label_down, yloc=yloc.abovebar)
Thank you

Answer 1

Make it global with := when you what to declare it again.
var float LongPrice = na
var float ShortPrice = na
if mmeLong
LongPrice := close // Get the Long signal's close price
label.new(bar_index, na, tostring(LongPrice),
color=color.green,
textcolor=color.white,
style=label.style_labelup, yloc=yloc.belowbar)
if mmeShort
ShortPrice := close - LongPrice // Get the Short signal's close price and minus it with the last Long close price.
label.new(bar_index, na, tostring(ShortPrice),
color=color.red,
textcolor=color.white,
style=label.style_label_down, yloc=yloc.abovebar)