标签：mail   pytho   类型   int   并且   xxx   str   rgs   字符   

def selfAdd(a):
    a += a
a_int = 1
print(‘a_int1:‘,a_int)
selfAdd(a_int)
print(‘a_int2:‘,a_int)
输出结果:
a_int1: 1
a_int2: 1

a_list =[1,2]
print(‘a_list1:‘,a_list)
selfAdd(a_list)
print(‘a_list2;‘,a_list)
输出结果:
a_list1: [1, 2]
a_list2; [1, 2, 1, 2]

‘‘‘Python中函数的参数是引用传递(注意不是值传递). 对于不可变类型(数值int,字符串string,元祖tuple),
因变量不能更改,所以运算不会影响到
变量自身;  而对于可变类型(列表,字典)来说,函数体运算可能会更改传入的参数变量‘‘‘

def extendList(val, list_test=[]):
    list_test.append(val)
    print(‘list_test: >>‘,list_test)
    return list_test
list_test1 = extendList(10)  # 
print ("list_test1_first= %s" % list_test1)
list_test2 = extendList(123,[]) #
list_test3 = extendList(‘a‘) #
print ("list_test1 = %s" % list_test1)
print ("list_test2 = %s" % list_test2)
print ("list_test3 = %s" % list_test3)
输出:
list_test: >> [10]
list_test1_first= [10]
list_test: >> [123]
list_test: >> [10, ‘a‘]
list_test1 = [10, ‘a‘]
list_test2 = [123]
list_test3 = [10, ‘a‘]

位置参数和*

在*参数后面还有参数市,一定要是位置参数指明age=?,并且要放在最后, 如果参数中出现 ＊users,传递的参数就可以不再是固定个数，传过来的所有参数打包元祖

def send_alert(msg,*users,age): # ([‘alex‘,‘xxx‘,‘iiii‘],) --> (‘alex‘,‘xxx‘,‘iiii‘)
    for u in users:
        print(‘报警发送给‘,u)
send_alert(‘别他么狼了‘,*[‘alex‘,‘xxx‘,‘iiii‘],age=33)
输出: 报警发送给 alex
报警发送给 xxx
报警发送给 iiii


send_alert(‘别他么狼了‘,[‘alex‘,‘xxx‘,‘iiii‘],age=34)
输出:报警发送给 [‘alex‘, ‘xxx‘, ‘iiii‘]


send_alert("alex","rain",‘eric‘,age=22)
输出:报警发送给 rain
报警发送给 eric

def send_alert(msg,*args):

    print(‘sending msg ....‘,msg,args)

    if args:
        print(args[0])

send_alert(‘cpu alert...‘)
send_alert(‘cpu alert...‘,‘email‘)
send_alert(‘cpu alert...‘,‘weixin‘,1)
输出:
sending msg .... cpu alert... ()
sending msg .... cpu alert... (‘email‘,)
email
sending msg .... cpu alert... (‘weixin‘, 1)
weixin

函数的默认参数是可变不可变引起的奇怪返回值

标签：mail   pytho   类型   int   并且   xxx   str   rgs   字符   

原文地址：https://www.cnblogs.com/heris/p/14044328.html