函数：函数是组织好的，可重复使用的，用来实现单一，或相关联功能的代码段。
函数的定义
定是函数使用def关键字
1 2 3 4 | def myfunc(x):
if x >= 0:
return x else:
return -x
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空函数
参数检查
1 2 3 4 5 6 7 | def checkfunc(x):
if not isinstance(x,(int,float)):
raise TypeError("must be int or float type!")
if x >= 0:
return x
else:
return -x
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返回多个值
1 2 3 4 5 | def price(x):
apple=x*2
banana=x*2.5
return apple,banana
a,b=price(1)
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函数的参数
必选参数parameter
1 2 3 4 5 | def printdetail1(name,age,telephone):
print("姓名:",name)
print("年龄:",age)
print("电话:",telephone)
printdetail1("Jack",12,12356435678)
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默认参数parameter=value
1 2 3 4 5 6 | def printdetail2(name,age,telephone,gender='fale'):
print("姓名:",name)
print("性别:",gender)
print("年龄:",age)
print("电话:",telephone)
printdetail2("Jack",12,12356435678,gender='female')
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可变参数*
1.不定长传参
1 2 3 | def fun1(*number):
for i in number:
print(i)fun1(1,2,3,4,5,6,7,8)
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2.元组和列表的压包
1 2 3 4 5 6 7 | def fun2(*number):
s=0
for i in number:
s+=i
print(s)
fun2(*[1,2,3,4,5])
fun2(*(1,2,3,4,5))
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关键参数**
使用方法一
1 2 3 4 5 | def fun(id,name,**kargs):
print("id:",id)
print("name:",name)
print("others:",kargs)
fun(2,"xiaohua",sex="man",age='12')
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使用方法二
1 2 3 4 5 6 | extra={'sex': 'man', 'age': 12}
def fun(id,name,**kargs):
print("id:",id)
print("name:",name)
print("others:",kargs)
fun(2,"xiaohua",sex=extra['sex'],age=extra['age'])
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使用方法三
1 2 3 4 5 6 | extra={'sex': 'man', 'age': 12}
def fun(id,name,**kargs):
print("id:",id)
print("name:",name)
print("others:",kargs)
fun(2,"xiaohua",**extra)
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关键字参数*
1 2 3 4 5 6 7 | def fun(name,age,*,city,job,completion):
print("name:",name)
print("age:",age)
print("city:",city)
print("job:",job)
print("completion:",completion)
fun('Jack',12,city='shanghai',job='teacher',completion=True)
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命名关键字参数需要一个特殊分隔符*，后面的参数被视为命名关键字参数
如果函数定义中已经有了一个可变参数，后面跟着的命名关键字参数就不再需要一个特殊分隔符*了
参数组合
1 2 3 4 5 6 | def fun(parameter,*args,keyparameter,**kargs):
print(parameter)
print(args)
print(keyparameter)
print(kargs)
fun(1,*(1,2,3,4),keyparameter=True,**{'id':2})
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参数定义的顺序必须是：必选参数、默认参数、可变参数、命名关键字参数和关键字参数
函数的递归
1 2 3 4 5 | #阶乘计算
def fact(n):
if n == 1:
return 1
return n * fact(n-1)
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