ord:返回字符的ASSIC码值
>>> ord('a')97
chr:输入ASSIC值,返回字符
>>> chr(99)'c'
round:四舍五入
>>> round(8.9)9
enumerate:循环访问数组
>>> for i,item in enumerate(li,1):... print(i,item)... 2 alex3 eric4 lili
eval: 识别字符串中的运算符
>>> eval("6*8")48