Returns the index of the current resolution in effect

 SetScreenResolution([index])

Takes

Number index (optional)

This value specifies the new screen resolution, it must be the index of one of the values yielded by GetScreenResolutions().

Passing nil will default this argument to 1, the lowest resolution available

Returns

Nothing

Example

local resolutions = {GetScreenResolutions()}
for i,entry in resolutions do
  if entry == '1024x768' then
    SetScreenResolution(i)
    break
  end
end