Python function initial knowledge and file manipulation

File operations

Open File: 文件句柄  =open(‘文件路径‘, ‘模式‘)

Mode of open File

W #以写的方式打开 (unreadable, does not exist then created, exists delete content) a #以追加的模式打开 (readable, nonexistent then created, append content exists) r                     #以只读模式打开 "+" means you can read and write a file r+ #以读写的模式打开w + #以读写的模式打开 A +     #以读写的模式打开 "B" means processing the binary file RB #以二进制模式读打开 WB #以二进制写模式打开 AB #以二进制追加模式打开 rb+ #以二进制读写模式打开wb + #以二进制读写模式打开ab + #以二进制读写模式打开 "U" means you can convert \ r \ r \ n \          　 　 N (same as R or r+ mode) rur+u3 fp = open ("Test.txt", W) fp.close #关闭文件, habit, open the file, after use, remember to close, otherwise it may be reported Valueerrorfp.fileno #返回一个文件描述符, use the underlying operation to request system I/O operations Fp.flush #刷新文件内容缓冲区fp. Isatty #文件是否是一个终端设备文件 (Unix system) F P.next #获取下一行的数据, there is no error.                The for I in File:print I.strip () is the call to this next () method Fp.read ([size]) #读取指定字节数的数据 in bytes fp.readline ([size]) #读一行, if size is defined, it is possible to return a portion of Fp.readlines ([size]) in a row #把文件每一行作为一个list的一个成员 and return the LISt.                                         Internal or call ReadLine () method Fp.seek (Offset[,whence]) #将文件操作移动到offset的位置, this offset is generally relative to the beginning of the file calculation, generally an integer,                                         #0 calculate from the beginning #1 start at the current position #2 never see the end of the Fp.tell #告诉文件操作的当前位置, calculate the Fp.truncate #把文件裁成规定的大小 starting at the beginning, and the default is to crop to the current                          Location of the file action tag Fp.write #往文件里面写内容fp. Writelines #将一个字符串列表写入文件fp. Closed　　　　　　　 　　　　　　    #关闭文件fp. Encoding fp.errors Fp.mode Fp.name
Fp.newlines
Fp.softspace

　　

 With application1, in order to avoid opening the file, forget to close, you can manage the context:

With open ("Log.txt", "R") as F:                #只读的方式打开文件, alias is F for line in    F:                                                  print line                            #打印每一行                                              # Internal automatically shuts down and frees file resources after execution is complete

　　

2, after python2.7, with also supports the simultaneous management of multiple file contexts

With open ("Log1.txt") as Obj1  , open ("Log2.txt") as  Obj2: #可以进行复制的操作 for line in    obj1:         Obj2.write (line)  

　　

python reads files in several poses per line

2. File = Open ("A.log", "R") Whiletrue: Line        = File.readline ()        If the line: Break        Passimport fileinputfile = Open ("A.log", "R") for line in Fileinput.input ("A.log"):        passfile = open ("A.log", "R") Whiletrue:        lines = File.readlines (100000)        If not lines:                broke        for line in lines:                passfile = open ("A.log", "R")                         # Equivalent  to with open ("A.log", "R") as F: # for Line in F: For line in                     file:                                #                           Pass             passfile = open ("A.log", "R")                         #已经废弃for Line in File.xreadlines ():        

   　　

4.                                  

Custom functions have always followed process-oriented programming, similar to Shell scripting, by piling up some commands to handle things, according to the business's Logitech top-to-bottom implementation capabilities

1. Whiletrue:    If CPU utilization > 90%:        #发送邮件提醒        Connect mailbox server        Send mail        off connection      if hard disk use space > 90%:        #发送邮件提醒        Connect mailbox server        Send mail        close connection      If memory consumption > 80%:        #发送邮件提醒        Connect mailbox server        Send mail        close connection

   Look at the above code, you can extract the contents of the IF statement common, as follows:

def send mail (content)    #发送邮件提醒    connect a mailbox server to    send mail    off connection while  True:      If CPU utilization > 90%:        send mail (' CPU alert ')      if HDD uses space > 90%:        send mail (' HDD alert ')      if memory consumption > 80%:      Send mail ("Memory Alarm")

For the two implementations, the second display is better than the first reuse and readability, which is also the difference between functional programming and process-oriented programming.       function: A function code is encapsulated in a function, it will not need to be repeated later, only need to call the function to    Object-oriented: classify and encapsulate functions to make development "faster, stronger ..." " 
Functional Programming The most important thing is to enhance the reusability and readability of code         definition and use of functions

1. def  foo (args):    print "hello,world!"    return Argsret = foo (name) print RET

   　　

Note: The above is called a function, the wrong write       foo (name) changed to foo ("name") Why should arguments be used for parameters of functions?

1. def send mail (message content)                  #邮件内容为参数 # Send mail reminder to connect mailbox server send mail close connection whiletrue:if CPU utilization >90%: Send Message ("CPU alarm up. If the hard disk uses space >90%: Send mail ("hdd alarm up.") If memory consumption >80%: Send Message ("Memory alarm is up.") ")

types of parameters in a function1, general parameters

1. def func (args):    print Argsfunc ("BUDONGHSU")

   　　

 2, default parameters

1. def func (Name,age =18):    print "%s:%s"% (Name,age) func ("Budongshu", +) func ("Budongshu") Run Result: Budongshu : 19budongshu:18

   　　

NOTE: The default parameter is placed in the last face of the parameter list
 3, dynamic parameters

1. def func (*arg):              #可以接收列表, tuple, string    print arg execution way one name =[1,2,3,4]func (name) name = ("A", "B") func (name) execution mode two func (" BDS ", 123)  execution Result:                           #返回的是一个元组 ([1, 2, 3, 4],) ((' A ', ' B '),) (' BDS ', 123)

   　　

1. def func (**kwargs):                 #可以接收字典   

   　　

1. def foo (*arg,**kwargs):        print ' arg = ', arg        print ' Kwargs = ', Kwargs        

   　　

1.  运行结果：

2. arg =  (1,2,3,4) Kwargs ={}-------------------------arg =  () Kwargs ={' A ': 1, ' C ': 3, ' B ': 2}--------------------- ----arg =  (1,2,3,4) Kwargs ={' A ': 1, ' C ': 3, ' B ': 2}-------------------------arg =  (' A ', 1,none) Kwargs ={' A ': 1, ' C ': 3, ' B ': ' 2 '}-------------------------

   　　

Python e-mail#!/usr/bin/env python#conding: Utf-8 *_*Import SmtplibFrom email.mime.text import MimetextFrom email.utils import formataddr  msg = Mimetext (' My name is Budongshu ', ' plain ', ' utf-8 ')msg[' from '] = FORMATADDR (["Budongshu", ' [email protected] ')msg[' to ' = FORMATADDR (["QQ", ' [email protected] ')msg[' Subject ' = "Hello hero subnet" Server = Smtplib. SMTP ("smtp.126.com", +)server.login ("[Email protected]", "Your password")server.sendmail (' [email protected] ', [' [email protected] ',], msg.as_string ())server.quit ()Detailed test:         

From for notes (Wiz)

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Python function initial knowledge and file manipulation