python（面试题一）

1 a,b = 0, 1
2 while b<100:
3     print (b),
4     a, b = b, a+b

def choose(bool, a, b):
    return (bool and [a] or [b])[0]

for x in reversed(sequence):
    ... # do something with x..

for i in range(len(sequence)-1, -1, -1):
    x = sequence[i]
    <do something with x>

 1 函数                      描述
 2 int(x [,base ])         将x转换为一个整数
 3 long(x [,base ])        将x转换为一个长整数
 4 float(x )               将x转换到一个浮点数
 5 complex(real [,imag ])  创建一个复数
 6 str(x )                 将对象 x 转换为字符串
 7 repr(x )                将对象 x 转换为表达式字符串
 8 eval(str )              用来计算在字符串中的有效Python表达式,并返回一个对象
 9 tuple(s )               将序列 s 转换为一个元组
10 list(s )                将序列 s 转换为一个列表
11 chr(x )                 将一个整数转换为一个字符
12 unichr(x )              将一个整数转换为Unicode字符
13 ord(x )                 将一个字符转换为它的整数值
14 hex(x )                 将一个整数转换为一个十六进制字符串
15 oct(x )                 将一个整数转换为一个八进制字符串

1 >>> l = tuple(iplist)
2 >>> print l
3 (‘217.169.209.2:6666‘, ‘192.227.139.106:7808‘, ‘110.4.12.170:83‘, ‘69.197.132.80:7808‘, ‘205.164.41.101:3128‘, ‘63.141.249.37:8089‘, ‘27.34.142.47:9090‘)
4 >>> t = list(l)
5 >>> print t
6 [‘217.169.209.2:6666‘, ‘192.227.139.106:7808‘, ‘110.4.12.170:83‘, ‘69.197.132.80:7808‘, ‘205.164.41.101:3128‘, ‘63.141.249.37:8089‘, ‘27.34.142.47:9090‘]

1 >>> l = [1,1,2,3,4,5,4]
2 >>> list(set(l))
3 [1, 2, 3, 4, 5]
4 或者
5 d = {}
6 for x in mylist:
7     d[x] = 1
8 mylist = list(d.keys())

 1 #使用__metaclass__（元类）的高级python用法  
 2 class Singleton2(type):  
 3     def __init__(cls, name, bases, dict):  
 4         super(Singleton2, cls).__init__(name, bases, dict)  
 5         cls._instance = None  
 6     def __call__(cls, *args, **kw):  
 7         if cls._instance is None:  
 8             cls._instance = super(Singleton2, cls).__call__(*args, **kw)  
 9         return cls._instance  
10  
11 class MyClass3(object):  
12     __metaclass__ = Singleton2  
13  
14 one = MyClass3()  
15 two = MyClass3()  
16  
17 two.a = 3  
18 print one.a  
19 #3  
20 print id(one)  
21 #31495472  
22 print id(two)  
23 #31495472  
24 print one == two  
25 #True  
26 print one is two  
27 #True  

 1 #使用装饰器(decorator),  
 2 #这是一种更pythonic,更elegant的方法,  
 3 #单例类本身根本不知道自己是单例的,因为他本身(自己的代码)并不是单例的  
 4 def singleton(cls, *args, **kw):  
 5     instances = {}  
 6     def _singleton():  
 7         if cls not in instances:  
 8             instances[cls] = cls(*args, **kw)  
 9         return instances[cls]  
10     return _singleton  
11  
12 @singleton  
13 class MyClass4(object):  
14     a = 1  
15     def __init__(self, x=0):  
16         self.x = x  
17  
18 one = MyClass4()  
19 two = MyClass4()  
20  
21 two.a = 3  
22 print one.a  
23 #3  
24 print id(one)  
25 #29660784  
26 print id(two)  
27 #29660784  
28 print one == two  
29 #True  
30 print one is two  
31 #True  
32 one.x = 1  
33 print one.x  
34 #1  
35 print two.x  
36 #1  

 1 #! /usr/bin/env python
 2 #coding=utf-8
 3 import sys 
 4 import time 
 5 import poplib 
 6 import smtplib 
 7 #邮件发送函数
 8 def send_mail(): 
 9      try: 
10         handle = smtplib.SMTP(‘smtp.126.com‘,25) 
11         handle.login(‘XXXX@126.com‘,‘**********‘) 
12         msg = ‘To: XXXX@qq.com\r\nFrom:XXXX@126.com\r\nSubject:hello\r\n‘
13         handle.sendmail(‘XXXX@126.com‘,‘XXXX@qq.com‘,msg) 
14         handle.close() 
15         return 1
16     except: 
17         return 0
18 #邮件接收函数
19 def accpet_mail(): 
20     try: 
21         p=poplib.POP3(‘pop.126.com‘) 
22         p.user(‘pythontab@126.com‘) 
23         p.pass_(‘**********‘) 
24         ret = p.stat() #返回一个元组:(邮件数,邮件尺寸) 
25        #p.retr(‘邮件号码‘)方法返回一个元组:(状态信息,邮件,邮件尺寸)   
26     except poplib.error_proto,e: 
27         print "Login failed:",e 
28         sys.exit(1)
29     
30 #运行当前文件时，执行sendmail和accpet_mail函数
31 if __name__ == "__main__": 
32     send_mail() 
33     accpet_mail()

 1 import os.path
 2 import xlrd,sys
 3 
 4 Filename=’/home/tom/Desktop/1234.xls’
 5 if not os.path.isfile(Filename):
 6     raise NameError,”%s is not a valid filename”%Filename
 7 
 8 bk=xlrd.open_workbook(Filename)
 9 shxrange=range(bk.nsheets)
10 print shxrange
11 
12 for x in shxrange:
13     p=bk.sheets()[x].name.encode(‘utf-8′)
14     print p.decode(‘utf-8′)

1 reload(sys)
2 sys.setdefaultencoding(‘utf8′)

1 b1=[1,2,3]
2 b2=[2,3,4]
3 b3 = [val for val in b1 if val in b2]
4 print b3

1 b1=[1,2,3]
2 b2=[2,3,4]
3 b3 = [val for val in b1 if val not in b2]
4 print b3 

socket = socket.socket( family, type )

socket.bind( address )

socket.listen( backlog )

connection, address = socket.accept()

socket.connect( (host,port) )

 1 #coding:utf-8
 2 
 3 import socket
 4 if __name__ == ‘__main__‘:
 5     sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 6     sock.bind((‘localhost‘, 8001))
 7     sock.listen(5)
 8 
 9     while True:
10         connection,address = sock.accept()
11         try:
12             connection.settimeout(5)
13             buf = connection.recv(1024)
14             if buf == ‘1‘:
15                 connection.send(‘welcome to server!‘)
16             else:
17                 connection.send(‘please go out!‘)
18         except socket.timeout:
19             print ‘time out‘
20 
21         connection.close() 

 1 #coding:utf-8
 2 
 3 import socket
 4 import time
 5 
 6 if __name__ == ‘__main__‘:
 7     sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 8     sock.connect((‘localhost‘, 8001))
 9     time.sleep(2)
10     sock.send(‘1‘)
11     print sock.recv(1024)
12     sock.close() 

 1  try:  
 2        block  
 3     except [exception,[data…]]:  
 4        block  
 5      
 6     try:  
 7     block  
 8     except [exception,[data...]]:  
 9        block  
10     else:  
11        block  

1 raise [exception[,data]]  
2      
3     try:  
4         raise MyError #自己抛出一个异常  
5     except MyError:  
6         print ‘a error‘  
7      
8     raise ValueError,’invalid argument’  

1     import sys  
2     try:  
3        block  
4     except:  
5        info=sys.exc_info()  
6        print info[0],":",info[1]