Lua performance (arithmic and concatenation)

[Sideshow]

Hello

I constanly ask my self (and google) if there is no other way than this:
randomvar[arg][var][arg].y = randomvar[arg][var][arg].y + 1

I can find nothing about it, but why is there no other way, like:
randomvar[arg][var][arg].y += 1
And would it be 'faster' ?

Second: I read that the concatenation operator ".." is quite slow. What is a better way to do it. Table.concat? It is for a loop with 50 concats per seconds.

/run local begin = GetTime() for i=1,100000 do local str = "a" .. "b" .. "c" end print(GetTime()-begin)

/run local tconcat = table.concat local begin = GetTime() for i=1,100000 do local str = tconcat({"a","b","c"}) end print(GetTime()-begin)

The second one would be faster ? I can't test it right now

[Xubera]

i checked out the times

no addons, chilllin in Dal

first line

0.013999999995576
0.013000000006286
0.013999999995576
0.013999999995576
0.013000000006286


second line

0.11500000001979
0.14100000000326
0.14200000002165
0.14199999999255
0.14299999998184

regualur concat seems faster... and looks pretty swift

[Dridzt]

string.format("%s%d%s..whatever", str1,num1,str2,etc) should be faster than string concatenation when you know you have a number.

In all other situations the simple concatenation is cheaper I believe.

Not my investigation, just remember a relevant discussion on wowace with tests over a large number of iterations.

[SDPhantom]

You also have to consider additional overhead to using function calls. Examples, global variable access, local variable access, table indexing, etc.

[Sideshow]

Ok thanks.

I found out that, a loop of 1,000,000

200 .. 'K' takes 2.6 seconds
string.format("%i%s", 1, "K") takes 1 second



The big thing is offcourse concatenating numbers... When you have no numbers in your cnocatenation, it's better to use ..

[Xinhuan]

It will be even faster if you do

local format = format
for k = 1, 1000000 do
format("%i%s", 1, "K")
end

[Sideshow]

or

local format = format
for k = 1, 1000000 do
format("%iK", 1)
end


did my homework