First, the definition of the function def function name ():
Function body Code
Example:
#define function
DEF In Email ():
Print ( 'Send In Email')
# call to a function
In Email ()
Second, the function return value
DEF In Email ():
Print ( "Send In Email")
return "transmission success" # no return, default return None
RET = in Email () function return back # what value, ret return value is equal to
print (ret)
Note: upon return, the return of the internal function code encounters no longer performed.
Third, the general parameters of the function
def email (address): #address formal parameters
Print (address)
return True
ret = email ('[email protected] ') # call execution by value, the actual parameter
# parameter passing, the default value is based on transfer order can also be specified parameter arguments passed, it may not order
four functions the default parameters
# Note: there is a default value for a parameter on the back
def email (name, address = " [email protected]"): # name, address formal parameters, address has a default value [email protected]
Print (name, address)
return True
five, the dynamic parameters of the function
1) simple dynamic parameters
# Note: * number plus one, can be in the form of dynamic parameters, the conversion element group; ** plus two numbers, the conversion into a dictionary
def email (* addr, ** address):
Print (addr)
Print (address)
email (11, 22, 33, k1 = 123, k2 = 456) # dynamic function parameters, a plurality of parameters can be passed
Results:
(11,22,33)
{ 'K1': 123, 'K2': 456 }
2) is passed a list of dynamic parameters, a dictionary or tuples
2.1) passed argument list
DEF F1 (* args):
Print (args)
li = [11,22,33,44] #列表
f1(li) #结果为[11,22,33,44]
f1(*li) #结果为(11,22,33,44),注意在传入实参时，加入*号
2.2)实参传入字典
def f2(**kwargs):
print(kwargs)
dic = {'k1':789} #传入字典
f2(dic) #结果报错
f2(**dic) #结果为{'k1':789},注意在传入实参时，加入**号
六、全局变量、局部变量
P = "python" #p为全局变量，变量名一般大写，可以共享使用
def func():
a = 123 #a 为局部变量，变量名一般小写，只能在func()函数中使用
#如果在函数内想修改全局变量，则需要使用关键字global
global P
P = "java" #全局变量P的值被修改为"java"
print(a) #结果为123
print(P) #func()函数可以使用全局变量