好用的for循环与range

1. for循环

   # for 变量 in  可迭代对象：
   #	pass
   s = "1234567890"
   for each in s:          # 遍历字符串
       print(each)         # 1 2 3 4 5 6 7 8 9 0
   print(each)             # 0   注意
   

2. 占位符

   pass 和 ...

3. range

   • 语法range(start,end,step): 范围，从start到end，不包含end，步长step默认是1

   • python3中打印range()会打印本身，python2中会打印出列表

     for each in range(1,10):
     	print(each)
     # 1  2  3  4  5  6  7  8  9