table在删除元素时要注意，例

t = { "hello", "world", "!"}

t[1] = nil

此时print(#t) --输出3，就是说把表的元素置为nil并没有移除该表项。

但，若是：

t = {[1] = nil,[2] = 223,[3] = nil}function count(t)    local c = 0    for k, v in pairs(t) do        c = c + 1    end    return cendprint(count(t))--1

 再看更诡异的

1 t = { 2 [1] = 12, 3 [2] = nil, 4 [3] = 4 5 } 6  7 function count(t) 8     local c = 0 9     for k, v in pairs(t) do10         c = c + 111     end12     return c13 end14 15 print("------------------", #t)16 t2 = { "hello", "world", "!"}17 t2[1] = nil18 t2[22] = nil19 t2[9] = nil20 print("--------t2---------", #t2)21 for k, v in pairs(t2) do22     print(k, v)23 end24 25 print("--------------->")26 for i=1, #t2 do27     print(i, t2[i])28 end