Autohotkey / AHK - Param %1% not accessible within a function - command-line

Question

I'm having a problem with accessing the %1% ( Startup Param that has been passed to the Script by the console ) in Autohotkey.
When I use the following code (outside of a function):
Msgbox %1%
I get the output of the Param that has been passed to the Script. But as soon as I use the following Code:
HelloWorld() {
Msgbox %1%
}
HelloWorld()
The output is empty.
I also tried to assign %1% to a global variable, or to pass it to the Function as a parameter but it didn't work for me neither.
Thank you

Answer 1

I believe the command line parameter variables are considered global variables, so in order to use them in a non-expression context inside a function you have to declare them as global:
HelloWorld() {
global 1
Msgbox %1%
}
HelloWorld()
It gets even more confusing once you want to use them in expressions (such as using % in the text argument for MsgBox), since they will be treated as numbers so you have to indirectly access them through variables:
HelloWorld() {
;global 1
; Neither of these two expressions access the variable named "1"
;Msgbox % 1
;Msgbox % %1%
; You have to do this instead:
p := 1
MsgBox % %p% ; p is translated to 1 and then "1" is used as a variable name
}
HelloWorld()
Note that doing this doesn't require global 1.
If you're using the newest version of AHK, you instead probably want to use the newly introduced built-in variable A_Args, which is an array that holds the command line parameters. Being built-in, it doesn't have to be declared global, and it ultimately makes the code clearer:
HelloWorld() {
MsgBox % "Number of command line args received: " A_Args.Length() "`n"
. "First argument: " A_Args[1]
}
HelloWorld()

Answer 2

Just declare your cli variables as Global - outside the function - to make them globally available to any and all internal functions. For me, this is how I do it with my version of AHK (Version 1.1.25.01):
Global 1, 2, 3
HelloWorld() {
MsgBox Hello`t1:`t%1%`n`t2:`t%2%`n`t3:`t%3%
}
HelloWorld()
Note, these are different command lines:
"Scripts\myScript.ahk" one two three
"Scripts\myScript.ahk" "one two" three
"Scripts\myScript.ahk" "one" "two three"
"Scripts\myScript.ahk" "one two three"
The first is three separate parameters, the second and third, only two and the last is only one param (2 and 3 exist, but are empty).
Hth,