lua 截取字符串中的数字

-- 去除首尾空格
local function trim (s) 
  return ((s, "^%s*(.-)%s*$", "%1")) 
end 


local strtemp1 = '血瓶 x1';
local strtemp2 = '血瓶 x2';
local strtemp3 = '血瓶 x3';


local function chaifen(str)
local index,b = (str, 'x');
local strname = '';
local dwnum = 0;
if index then
print("***************")
dwnum = (str, index+1,-1);
strname = (str,1,index-1);

strname = trim(strname)
end
print(strname);
print((strname));
print(dwnum);

end