Imooc - Python3 入门教程: Python的函数
介绍Python代码最基本的抽象类型：函数，以及如何定义和调用函数
定义函数
# 标准写法
def my_abs(x):
if x >= 0:
return x
else:
return -x# 更 if/else 的写法
def my_abs(x):
if x >= 0: return x
return -x# 类3元表达式
def my_abs(x):
return x if x >= 0 else -x返回值
# 无返回
def list_sum(l):
result = 0
for num in l:
result = result + num
print('result is {}'.format(result))
return
# 多个返回
def data_of_square(side):
C = 4 * side
S = side * side
return C, S
C, S = data_of_square(16)
print('周长 = {}'.format(C)) # ==> 周长 = 64
print('面积 = {}'.format(S)) # ==> 面积 = 256 函数的参数
- 普通函数
- 可选参数函数
- 可变参数函数
# 类型判断
isinstance(100, int) # ==> True
isinstance(100.0, int) # ==> False
isinstance('3.1415926', str) # ==> True
# 默认参数(optional 可选参数)
def power(x, n=2):
s = 1
while n > 0:
n = n - 1
s = s * x
return s
# 可变参数
def average(*args):
sum = 0
for item in args:
sum += item
avg = sum / len(args)
return avg
# 又一个可变参数
def manyArgs(*arg):
print("I was called with", len(arg), "arguments:", arg)
manyArgs(1, 2, 3, 4)
# I was called with 4 arguments: (1, 2, 3, 4)
# 可选参数(optional)
def print_student(student, grade="Fifth"):
print("{} is in {} grade.".format(student, grade))可变关键字参数
Python函数提供可变关键字参数，对于可变关键字参数，可以通过关键字的名字key找到对应的参数值，想想这和我们之前学习过的什么类似？是的没错，dict，Python会把可变关键字参数当作dict去处理；对于可变关键字参数，一般使用**kwargs来表示
def info(**kwargs):
print(
'name: {}, gender: {}, age: {}'.format(
kwargs.get('name'),
kwargs.get('gender'),
kwargs.get('age'))
)
info(name='Alice', gender='girl', age=16)让 dict 类型以 点 方式去调用
class dotdict(dict):
"""dot.notation access to dictionary attributes"""
__getattr__ = dict.get
__setattr__ = dict.__setitem__
__delattr__ = dict.__delitem__
def fun1(s1, s2, **kwargs):
args = dotdict(kwargs)
print(args)
print(args["verbose"])
# 精华在这一句
print(args.verbose)
# call the args with dot function
fun1(1, 2, verbose=True){'verbose': True}
True
True