Return a percentage sign in Lua string.format

Question

In a modification script I'm developing for an online game, I'm attempting to display the current percentage of a number.

function()
    local z = math.max(0, UnitPower("player")) / math.max(1, UnitPowerMax("player")) * 100;
    return string.format("%.f", z);
end

The code above displays the percentage correctly.

However, I am having a difficult time getting the actual percentage sign to show up without throwing errors everywhere.

I've tried adding print("%%") before ending the function as well as after the function, but it doesn't seem to work.

Answer 1

The function string.format, like printf in C, requires the percent sign to be doubled when you want it verbatim. This is not the case for print or io.write functions !

So you certainly want this :

function()
  local z = math.max(0, UnitPower("player")) / math.max(1, UnitPowerMax("player")) * 100;
  return string.format("%.f %%", z);
end

Answer 2

Figured it out.

function()
    local z = math.max(0, UnitPower("player")) / math.max(1, UnitPowerMax("player")) * 100;
    return string.format("%.f", z) .. "%%";
end

Just added .. "%%"; the value shown is now 100% (where 100 is the current percentage.

Super late edit:
This was part of some custom code being entered into an addon for the video game World of Warcraft, and this is the solution for the goal I wanted to achieve because the author was calling string.format() around the "custom code" input. Refer to the other answer on this question for the standard Lua solution.