for 循环用于对一个序列进行遍历,用法如下:

In [4]: for i in 'abcd':
   ...:     print(i)
   ...:     
a
b
c
d
In [13]: for i in range(1, 10):    # else 语句会在循环正常执行完的情况下执行,如果遇到break则不执行
   ....:     if i%5 == 0:
   ....:         break
   ....:     print(i)
   ....: else:
   ....:     print("Hello")
   ....:     
1
2
3
4