#没有返回值的函数，其实返回的是None 
def run(name): 
    print name,'runing' #函数体语句从下一行开始，并且第一行必须是缩进的 
 
>>>run('xiaoming') 
xiaoming runing 
 
>>>print run('xiaoming') 
xiaoming runing 
None #如果没有ruturn语句，函数返回的是None 
 
#有返回值的参数 
def run(name): 
    return name+'runing' 
>>>r = run('xiaoming') 
>>>r 
xiaoming runing 

def run(name): 
    """ print somebody runing"""#写在函数体的第一行才叫文档字符串 
    print name,'runing'  

>>>run.__doc__ 
print somebody runing 

def run(name,age,sex): 
    print 'name :',name,'age:',age,'sex:',sex 
>>> run(age=23,name='xiaoming',sex='boy')#关键字绑定 
name:xiaoming age:23 sex:boy 

def run(name,age,sex): 
    print 'name :',name,'age:',age,'sex:',sex 
>>> run('xiaoming',name='xiaoming',sex='boy') 
SyntaxError: non-keyword arg after keyword arg 

def run(name,age=20,sex='girl'): 
    print name,age,sex 
>>>run('nana') 
nana 20 girl 
>>>run('nana',23) 
nana 23 girl 
>>>run('gg','boy')#使用的位置绑定，所以，python为将'boy'绑定在age上，而不是我们想要的sex上 
gg boy girl 
 
>>>run('gg',sex='boy')#混合关键字绑定，可以实现想要的效果 
gg 20 boy 

def run(name,age=10,sex): 
    print name ,age ,sex 
SyntaxError: non-default argument follows default argument gg 23 boy 

def run(name,age,sex='boy'): 
    print name,age,sex 

>>>run()#required argument missing 
>>>run(name='gg',23)#non-keyword argument following keyword 
>>>run('gg',name='pp')#duplicate value for argument 
>>>run(actor='xxxx')#unknown keyword 

>>>i = 5 
>>>def f(arg=i): 
>>>  print arg 
>>>i = 6 
>>>f() 
5 #结果是5 

>>> def f(a, L=[]): 
>>>  L.append(a) 
>>>  return L 
 
>>> print f(1) 
>>> print f(2) 
>>> print f(3) 
[1] 
[1, 2] 
[1, 2, 3] 
 
#可以用另外一种方式实现： 
>>> def f(a, L=None): 
>>>  if L is None: 
>>>    L = [] 
>>>  L.append(a) 
>>>  return L 

def run(name,*args): 
    print name,'runing' 
    for a in args : print a 
 
>>> run('gg','mm') 
gg runing 
mm 
>>> run('gg',1,2,'mm') 
gg runing 
1 
2 
mm 
>>> run('gg',1,1.02,['mm','gm']) 
gg runing 
1 
1.02 
['mm','gm'] 

def run(name,**args): 
    keys = args.keys() 
    for k in keys : 
       print k,args[k] 
 
>>> run('nana',type='open') 
type open 
>>> run('nana',type='open',title='gogo') 
type open 
title gogo 

#*arg 必须在**args的前面 
def run(name,*arg,**args): 
    for a in arg :print a 
    keys = args.keys() 
    for k in keys : 
       print k,args[k] 
>>> run('nn','mm',1,2,'oo',type='open',title='gogo') 
mm 
1 
2 
oo 
type open 
title gogo 

>>> range(3, 6)       # normal call with separate arguments 
[3, 4, 5] 
>>> args = [3, 6] 
>>> range(*args)      # call with arguments unpacked from a list 
[3, 4, 5] 

>>> def make_incrementor(n): 
...   return lambda x: x + n #相当于创建了一个一x为参数的匿名函数？ 
... 
>>> f = make_incrementor(42)#f = make_incrementor(n=42)，设置n的值 
>>> f(0)#其实调用的是匿名函数？ 
42 
>>> f(1) 
43 
 
#看下面一个例子报的错误就可以明白一点了 
>>>def t(n): 
...     print x*n 
>>>m = t(2) 
Traceback (most recent call last): 
 File "<pyshell#85>", line 1, in <module> 
  m = t(2) 
 File "<pyshell#84>", line 2, in t 
  print x*n 
NameError: global name 'x' is not defined 

>>> x =10 
>>> def t(n): 
...    print x*n 
>>> m = t(2) 
20