1.len(x):傳回s字串的長度，也就是s總共包含幾個字元，例如:
>>>len("hello") 5 #hello總共由5個字元組成
2.str(n):傳回數值參數n轉為字串的結果，例如:
>>>str(125.5) '125.5'
Copyright © All rights reserved | This template is made with by Colorlib