字符串格式化方法：f-strings

f-strings 是指以 f 或 F 开头的字符串，其中以 {} 包含的表达式会进行值替换。

下面看下 f-strings 的使用方法

1.基本使用

>>> name = 'hoxis'
>>> age = 18
>>> f"hi, {name}, are you {age}"
'hi, hoxis, are you 18'
>>> F"hi, {name}, are you {age}"
'hi, hoxis, are you 18'

2.运算表达式

>>> f"{ 2 * 3 + 1}"
'7'

• 3.调用函数

>>> def test(input):
...     return input.lower()
...
>>> name = "Hoxis"
>>> f"{test(name)} is handsome."
'hoxis is handsome.'

也可以直接调用内置函数：

>>> f"{name.lower()} is handsome."
'hoxis is handsome.'

4.在类中使用

>>> class Person:
...            def __init__(self,name,age):
...                self.name = name
...                self.age = age
...            def __str__(self):
...                return f"{self.name} is {self.age}"
...            def __repr__(self):
...                return f"{self.name} is {self.age}. HAHA!"
>>> hoxis = Person("hoxis",18)
>>> f"{hoxis}"'hoxis is 18'
>>> f"{hoxis!r}"'hoxis is 18. HAHA!'
>>> print(hoxis)hoxis is 18
>>> hoxishoxis is 18. HAHA!

5.多行 f-string

>>> name = 'hoxis'
>>> age = 18
>>> status = 'Python'
>>> message = {... f'hi {name}.'
... f'you are {age}.'
... f'you are learning {status}.'
... }
>>> message{'hi hoxis.you are 18.you are learning Python.'}

这里需要注意，每行都要加上 f 前缀，否则格式化会不起作用：

>>> message = {... f'hi {name}.'
... 'you are learning {status}.'... }
>>> message{'hi hoxis.you are learning {status}.'}