str.format()

1. 通过位置

>>> "{0} {1}".format("hello", "world")
'hello world'
>>> "{} {}".format("hello", "world")
'hello world'
>>> "{1} {0} {1}".format("hello", "world")
'world hello world'

 2. 通过关键字

>>> "I am {name}, age is {age}".format(name="huoty", age=18)
'I am huoty, age is 18'
>>> user = {"name": "huoty", "age": 18}
>>> "I am {name}, age is {age}".format(**user)
'I am huoty, age is 18'

 3. 通过对象属性

>>> class User(object):
...     def __init__(self, name, age):
...         self.name = name
...         self.age = age
...         
...     def __str__(self):
...         return "{self.name}({self.age})".format(self=self)
...     
...     def __repr__(self):
...         return self.__str__()
...     
...
>>> user = User("huoty", 18)
>>> user
huoty(18)
>>> "I am {user.name}, age is {user.age}".format(user=user)
'I am huoty, age is 18'

 4. 通过下标

>>> names, ages = ["huoty", "esenich", "anan"], [18, 16, 8]
>>> "I am {0[0]}, age is {1[2]}".format(names, ages)
'I am huoty, age is 8'
>>> users = {"names": ["huoty", "esenich", "anan"], "ages": [18, 16, 8]}
>>> "I am {names[0]}, age is {ages[0]}".format(**users)

 5. 指定转换

“!r” 对应 repr()； “!s” 对应 str(); “!a” 对应 ascii()。
>>> "repr() shows quotes: {!r}; str() doesn't: {!s}".format('test1', 'test2')
"repr() shows quotes: 'test1'; str() doesn't: test2"

类似

a = "a"
"%s"%a
>>>"a"

"'%s'"%a
>>>"'a'"

字符串对齐：

str.rjust(width[, fillchar]) 右对齐

str.ljust(width[, fillchar]) 左对齐

str.center(width[, fillchar]) 中间对齐