Python 的 f-strings 作用远超你的预期

str_value = "hello，python coders"print(f"{ str_value = }")# str_value = 'hello，python coders'

num_value = 123print(f"{num_value % 2 = }")# num_value % 2 = 1

import datetimetoday = datetime.date.today()print(f"{today: %Y%m%d}")# 20211019print(f"{today =: %Y%m%d}")# today = 20211019

>>> a = 42>>> f"{a:b}" # 2进制'101010'>>> f"{a:o}" # 8进制'52'>>> f"{a:x}" # 16进制，小写字母'2a'>>> f"{a:X}" # 16进制，大写字母'2A'>>> f"{a:c}" # ascii 码'*'

>>> num_value = 123.456>>> f'{num_value = :.2f}' #保留 2 位小数'num_value = 123.46'>>> nested_format = ".2f" #可以作为变量>>> print(f'{num_value:{nested_format}}')123.46

>>> x = 'test'>>> f'{x:>10}' # 右对齐，左边补空格'test'>>> f'{x:*>> f'{x:=^10}'# 居中，左右补='===test==='>>> x, n = 'test', 10>>> f'{x:~^{n}}' # 可以传入变量 n'~~~test~~~'>>>

>>> x = '中'>>> f"{x!s}" # 相当于 str(x)'中'>>> f"{x!r}" # 相当于 repr(x)"'中'"

class MyClass:def __format__(self, format_spec) -> str:print(f'MyClass __format__ called with {format_spec=!r}')return "MyClass()"print(f'{MyClass():bala bala%%MYFORMAT%%}')

MyClass __format__ called with format_spec='bala bala%%MYFORMAT%%'MyClass()