463 posts
Location
Star Wars
Posted 17 March 2016 - 04:00 PM
How does work the # operator?
I know, that I can preload APIs or something like that, but how does it work?
3057 posts
Location
United States of America
Posted 17 March 2016 - 04:32 PM
# translates roughly to "get length of"
It works on strings and tables.
1140 posts
Location
Kaunas, Lithuania
Posted 17 March 2016 - 04:37 PM
For tables the length (#) operator counts numerical indexes of a table, starting from the index 1 until it hits a nil value. If you're using a table as an array it will work as a simple array length operator. For strings the length operator counts the number of bytes (characters) of the string. You could write it (for tables) as a function in Lua like so:
local function length (tab)
local len, i = 0, 1
while tab[i] ~= nil do
len = len + 1
i = i + 1
end
return len
end
local t = {
1, 2, 3
}
print(#t) --> 3
print(length(t)) --> 3
EDIT: got ninja'd and forgot about strings.
Edited on 17 March 2016 - 03:41 PM
355 posts
Location
Germany
Posted 17 March 2016 - 06:42 PM
I think OP confused it with another language. cant remember which though. does anybody know of such preloading of libraries?
1140 posts
Location
Kaunas, Lithuania
Posted 17 March 2016 - 06:46 PM
I think OP confused it with another language. cant remember which though. does anybody know of such preloading of libraries?
Might be pre-processor directives. They are used in C and C++, as well as many other languages. There are some pre-processors written for CC. Sewbacca, are you talking about these:
#include <string>
#define FOO 1
#define BAR
#ifdef BAR
#endif
Edited on 17 March 2016 - 05:47 PM
463 posts
Location
Star Wars
Posted 17 March 2016 - 07:01 PM
I think OP confused it with another language. cant remember which though. does anybody know of such preloading of libraries?
Might be pre-processor directives. They are used in C and C++, as well as many other languages. There are some pre-processors written for CC. Sewbacca, are you talking about these:
#include <string>
#define FOO 1
#define BAR
#ifdef BAR
#endif
Yes, I mean that, but it doesn't work.
3057 posts
Location
United States of America
Posted 17 March 2016 - 07:01 PM
It doesn't work because that isn't Lua.
463 posts
Location
Star Wars
Posted 17 March 2016 - 07:21 PM
HereMaybe, I don't understand it or it doesn't work in CC.
3057 posts
Location
United States of America
Posted 17 March 2016 - 07:41 PM
Why would the command to run a lua program on Unix be valid lua code?
463 posts
Location
Star Wars
Posted 17 March 2016 - 08:06 PM
I thought, that you can load an API before executing the code, so I didn't understand it :(/>.
355 posts
Location
Germany
Posted 17 March 2016 - 08:49 PM
What you are referring to are shell default application headings for files. In order to run a lua script, you would need to pass its file as argument to the lua interpreter executable.
Which is kind of annoying, even more so when not set in the current PATH.
What Lua does allow is to create this shell line in the first line of the file, which is actually ignored by the interpreter, when it starts with #!
Following is the path of the default application to open it with. This is also used in normal shellscripts. Lua is just compatible with that style, telling the interpreter of the file via this line. It allows you to handle your script much like a program, rather than a text file.
Edit: The reason it doesn't work in CC is probably because the java lua interpreter doesnt support ignoring this line.
In CC you dont even need it though. Typing a filename into the shell automatically executes it via dofile. so interpreter must be set, since everything is already in a lua environment
Edited on 17 March 2016 - 07:53 PM
570 posts
Posted 17 March 2016 - 10:31 PM
…
For the sake of completeness, it's called a
Shebang.