Lua print on the same line
In Pascal, I have write
and writeln
. Apparently Lua's print
is similar to writeln
of Pascal. Do we have som开发者_高级运维ething similar to write
of Pascal? How can consecutive print commands send their output to the same line?
print("Hello")
print("World")
Output:
Hello
world
I want to have this:
Hello world
Use io.write
instead print
, which is meant for simple uses, like debugging, anyway.
Expanding on lhf's correct answer, the io
library is preferred for production use.
The print
function in the base library is implemented as a primitive capability. It allows for quick and dirty scripts that compute something and print an answer, with little control over its presentation. Its principle benefits are that it coerces all arguments to string
and that it separates each argument in the output with tabs and supplies a newline.
Those advantages quickly become defects when detailed control of the output is required. For that, you really need to use io.write
. If you mix print
and io.write
in the same program, you might trip over another defect. print
uses the C stdout
file handle explicitly. This means that if you use io.output
to change the output file handle, io.write
will do what you expect but print
won't.
A good compromise can be to implement a replacement for print
in terms of io.write
. It could look as simple as this untested sample where I've tried to write clearly rather than optimally and still handle nil
arguments "correctly":
local write = io.write
function print(...)
local n = select("#",...)
for i = 1,n do
local v = tostring(select(i,...))
write(v)
if i~=n then write'\t' end
end
write'\n'
end
Once you are implementing your own version of print
, then it can be tempting to improve it in other ways for your application. Using something with more formatting control than offered by tostring()
is one good idea. Another is considering a separator other than a tab character.
As an alternative, just build up your string then write it out with a single print
You may not always have access to the io
library.
You could use variables for "Hello" and "World". Then concatenate them later. Like this:
local h = "Hello"
local w = "World"
print(h..w)
It will be display, in this case, as "HelloWorld". But that's easy to fix. Hope this helped!
Adding on to @Searous's answer, try the following.
local h = "hello" local w = "world"
print(h.." "..w)
You can concatenate both together, just concatenate a space between both variables.
local h = "Hello"
local w = "World!"
print(h, w)
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