Sub

Flow control
Aptilis 1

Sub([parameters])

sub indicates the begining of a block of Aptilis lines.
In Aptilis, a programme can be divided in subs, but only one is necessary: the 'main' sub. That is the sub that is going to be run by default.
If you are running your script from the command line, you can retrieve the command line parameters by typing 'sub main(args[])' (see example 5).
A sub must be closed by end sub or end the_name_of_the_sub.
A sub can return a value with the 'return' keyword at any moment.
Returning values allows you to use subs as functions (see example 2).
You do not need the dollar sign in the 'sub' line of a sub, but you need to put the brackets '[]' to indicate that a given variable is going to be an array. (see example 3)

Example 1:
(This is actually a complete programme) 

sub main
print("Hello World!\n")
end main

Result: 
Hello World

Example 2:
(This is actually a complete programme) 

sub square(param)

return param * param

end square

sub main

c = square(3)
print(c)

// we could now say 'end main', but 'end sub' is equally good.
end sub

Result: 
9

Example 3:
(Passing an entire array) 

sub enumerate(param[])

n = getArraySize(param[])
for i=0 to n - 1
print(param[i]$, "\n")
end for

end enumerate

sub main

a[0] = "Homer" $
a[1] = "Marge" $
a[2] = "Bart" $
a[3] = "Lisa" $
a[4] = "Maggie" $

enumerate(a[])

end sub

Result: 
Homer
Marge
Bart
Lisa
Maggie

Example 4:
(Passing strings) 

sub capitalize(n)

c = asc(n$)
if c >= 97 and c <= 122
c = c - 32
end if

print(chr(c)$, mid(n$, 2)$)

end capitalize


sub main

s = "hello" $
capitalize(s$)

end main

Result: 
Hello

Example 5:
(Command line parameters) 

Assuming the script is started with 'aptilis.exe test.e.txt param1 param2 param3'

sub main(args[])

	for i = 0 to getArraySize(args[])-1
		print(args[i]$, "\n")
	end for

end main

Result: 
C:\APTILIS\APTILIS.EXE
test.e.txt
param1
param2
param3
As you can see, this is also the way to determine the filename of the script (args[1]$) and the location of aptilis.exe (args[0]$).