What does it do? for i=1,select('#',...)
I encountered the following code in a project that I'm working with. i don't understand the iteration part of for-loop. What is the select() function?
function _log (开发者_运维问答str,...)
local LOG="/tmp/log.web"
for i=1,select('#',...) do
str= str.."\t"..tostring( select(i,...) )
end
os.execute("echo \"".. str .."\" \>\> " .. LOG )
end
From the Lua manual:
If
index
is a number, returns all arguments after argument number index. Otherwise, index must be the string"#"
, and select returns the total number of extra arguments it received.
From this post on Lua's multiple arguments and the "select" function, you can convert into a table if you really need to:
function multiple_args(...)
local arguments = {...} -- pack the arguments in a table
-- do something --
return unpack(arguments) -- return multiple arguments from a table (unpack)
end
Finally, if you pass "#" as index, the function returns a count of the multiple arguments provided:
print(select("#")) --> 0
print(select("#", {1, 2, 3})) --> 1 (single table as argument)
print(select("#", 1, 2, 3)) --> 3
print(select("#", {1,2,3}, 4, 5, {6,7,8}) --> 4 (a table, 2 numbers, another table)
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