How to remove spaces from a string in Lua?

Question

I want to remove all spaces from a string in Lua. This is what I have tried:

string.gsub(str, \"\", \"\")
string.gsub(str, \"% \", \"\")
string.gsub(str, \"%s*\"         


        

Answer 1

For LuaJIT all methods from Lua wiki (except for, possibly, native C/C++) were awfully slow in my tests. This implementation showed the best performance:

function trim (str)
  if str == '' then
    return str
  else  
    local startPos = 1
    local endPos   = #str

    while (startPos < endPos and str:byte(startPos) <= 32) do
      startPos = startPos + 1
    end

    if startPos >= endPos then
      return ''
    else
      while (endPos > 0 and str:byte(endPos) <= 32) do
        endPos = endPos - 1
      end

      return str:sub(startPos, endPos)
    end
  end
end -- .function trim