Python3基础之函数用法

def 函数名(参数列表): 
  """文档字符串""" 
  函数体 
  return [expression] 

def fib(n): 
  """Print a Fibonacci series""" 
  a, b = 0, 1 
  while b < n: 
    print(b, end=' ') 
    a, b = b, a+b 
  print() 
 
fib(2000) # call 
f = fib  # assignment 
f(2000) 

a = 5     # 全局变量a 
 
def func1(): 
  print('func1() print a =', a) 
 
def func2(): 
  a = 21  # 局部变量a 
  print('func2() print a =', a)  
 
def func3(): 
  global a 
  a = 10  # 修改全局变量a 
  print('func3() print a =', a) 
 
func1() 
func2() 
func3() 
print('the global a =', a) 

def fun(name, age, gender): 
  print('Name:',name,'Age:',age,'Gender:',gender,end=' ') 
  print() 
 
fun('Jack', 20, 'man') # call 

def fun(name, age, gender): 
  print('Name:',name,'Age:',age,'Gender:',gender,end=' ') 
  print() 
 
fun(gender='man', name='Jack', age=20) # using keyword arguments 

def fun(a, b, c=5): 
  print(a+b+c) 
 
fun(1,2) 
fun(1,2,3) 

def fun(a, L=[]): 
  L.append(a) 
  print(L) 
 
fun(1) # 输出[1] 
fun(2) # 输出[1, 2] 
fun(3) # 输出[1, 2, 3] 

def fun(*args): 
  print(type(args)) 
  print(args) 
 
fun(1,2,3,4,5,6) 
 
# 输出： 
# <class 'tuple'> 
# (1, 2, 3, 4, 5, 6) 

def fun(**args): 
  print(type(args)) 
  print(args) 
 
fun(a=1,b=2,c=3,d=4,e=5) 
 
# 输出： 
# <class 'dict'> 
# {'d': 4, 'e': 5, 'b': 2, 'c': 3, 'a': 1} 

def fun(a=1, b=2, c=3): 
  print(a+b+c) 
 
fun()  # 正常调用 
list1 = [11, 22, 33] 
dict1 = {'a':40, 'b':50, 'c':60} 
fun(*list1)  # 解包列表 
fun(**dict1) # 解包字典 
 
# 输出： 
# 6 
# 66 
# 150 

lambda [arg1 [,arg2,.....argn]] : expression 

f = lambda x, y: x+y 
print(f(10, 20)) 

def make_fun(n): 
  return lambda x: x+n 
 
f = make_fun(15) 
print(f(5)) 

def fun(): 
  """Some information of this function. 
  This is documentation string.""" 
  return 
 
print(fun.__doc__)