for循环：用户按照顺序循环可迭代对象的内容

1. for循环字符串

msg = "string"for i in msg:    print(i)

执行结果为：

string

2. for循环列表

lst = ["a", "b", "c"]for i in lst:    print(i)

执行结果为：

abc

3. for循环字典

dic = {    "name": "yang",    "age": 18,    "sex": "male"}for key, value in dic.items():    print(key, value)

执行结果为：

name yangage 18sex male