求最大值，最小值及长度：
function maxn(t)
local mn = nil
for i, v in pairs(t) do
if (mn==nil) then
mn=v
end
if (mn<v) then
mn=v
end
end
return mn
end
function lenn(t)
local leng=0
for i,v in pairs(t) do
leng=leng+1
end
return leng;
end
function minn(t)
local min=nil
for i, v in pairs(t) do
if (min==nil) then
min=v
end
if (min>v) then
min=v
end
end
return min
end
tbl = {[1]=15,[2]=320,[3]=6,[25]=99,[22]=2}
print("Max:",maxn(tbl))
print("Min:", minn(tbl))
print("Length:",lenn(tbl))