f-strings are added to the standard library python3.6 start new wording formatted output, prior to the high ratio of% s or formatted output format simplified and more efficient, very easy to use.
2.1 Simple example
His configuration is F (f) + str form of, want to replace with the position in the string {} placeholder, the format is similar, but with replacement of the contents written back in the string, he can be directly identified.
name = '章超印'
age = 17
sex = '男'
msg = F'姓名：{name},性别：{age}，年龄：{sex}' # 大写字母也可以
msg = f'姓名：{name},性别：{age}，年龄：{sex}'
print(msg)
'''
输出结果：
姓名：章超印,性别：17，年龄：男
'''2.2 Any expression
He can add any expression, it is very easy:
print(f'{25*4}') # 100
name = 'jacky'
print(f"全部大写：{name.upper()}") # 全部大写：JACKY
# 字典也可以
student = {'name': '章超印', 'age': 18}
msg = f"The student is {student['name']}, age {student['age']}"
print(msg) # The student is 章超印, age 18
# 列表也行
lst = ['章超印', 18]
msg = f'姓名：{lst[0]},年龄：{lst[1]}.'
print(msg) # 姓名：章超印,年龄：18.
#列表推导式也可以
s = f"{[i for i in range(9) if i > 3]}"
print(s)2.3 an insert function
Corresponding functions can be accomplished by a function, and then returns the value returned to a position corresponding to a string
def sum_a_b(a,b):
return a + b
a = 1
b = 2
print('求和的结果为' + f'{sum_a_b(a,b)}')More than 2.4-line f
name = 'Jacky'
age = 18
character = 'excellent'
# speaker = f'''Hi {name}.
# You are {age} years old.
# You are a {character} guy!'''
speaker = f'Hi {name}.'\
f'You are {age} years old.'\
f'You are a {character} guy!'
print(speaker)2.5 Other details
print(f"{73}") # 73
print(f"{{73}}") # {73}
print(f"{{{73}}}") # {73}
print(f"{{{{73}}}}") # {{73}}
print(f"{{{{{73}}}}}") # {{73}}
print(f"{{{{{{73}}}}}}") # {{{73}}}
print(f"{{{{{{{73}}}}}}}") # {{{73}}}
print(f"{{{{{{{{73}}}}}}}}") # {{{{73}}}}
print(f"{{{{{{{{{73}}}}}}}}}") # {{{{73}}}}
# ! , : { } ;这些标点不能出现在{} 这里面。
# print(f'{;12}') # 报错
# 所以使用lambda 表达式会出现一些问题。
# 解决方式：可将lambda嵌套在圆括号里面解决此问题。
x = 5
print(f'{(lambda x: x ** 2) (x)}') # 25