Python Learning Notes Day04-python strings, lists, tuples

String

Sequence

Sequence type operator

Sequence operator	Role
Seq[ind]	Get the element labeled IND
SEQ[IND1:IND2]	Get subscript from Ind1 to ind2 element combination
SEQ * Expr	Sequence repeats expr times
SEQ1 + SEQ2	Connecting sequences seq1 and SEQ2
obj in seq	Determine if the obj element is included in the SEQ
Obj not in seq	Determine if the obj element is not included in the SEQ

Built-in functions

/tbody>

functions	meaning
list (ITER)	Convert an iterative object to a list
str (obj)	Convert obj object to string
tuple (ITER)	Convert an iterative object to a tuple object

>>> list (' Hello ')
[' H ', ' e ', ' l ', ' l ', ' O ']
>>> list ([' Hello ', ' world ')
[' Hello ', ' world ']
>>> str ([' Hello, ', ' World '])
"[' Hello, ', ' World ']"

Len (seq): Returns the length of the SEQ

Max (Iter,key=none): Returns the maximum value in ITER

>>> Max (' ABF ')
' F '
>>> Ord (' a ')
97
>>> Ord (' F ')
102
>>> Max ([10,234,3421,12])
3421

Enumerate: Takes an iterative object as a parameter and returns a enumerate object

>>> for I,j in Enumerate (alist):
... print "Index%d:%s"% (i,j)
...
Index 0:hello
Index 1:world

reversed (seq): Takes a sequence as a parameter, returning an iterator that is accessed in reverse order

        sorted (ITER): Accepts an iterative object as an argument, Returns an ordered list of

            > >> alist = [32,43,323,55]
            > >> Sorted (alist)
            [32, 43, 55, 323 ]
            >>> for item in reversed ( alist):
            ...  Print Item
           &NBSP, .....
            55
             323
             43
            32

String

String operator

Comparison operators: String sizes are compared by ASCII value size

Slice operator: [], [:], [::]

Member relationship operators: in, not in

>>> pystr = ' Hello world! '
>>> Pystr[::2]
' HLOWRD '
>>> Pystr[::-1]
'!dlrow Olleh '
Small exercise:

Check identifiers

1, the program accepts user input

3. Determine if the identifier entered by the user is legal

#!/usr/bin/env python

Import string

First_chs = String.letters + ' _ '
Other_chs = First_chs + string.digits
def check_id (myID):
If myid[0] not in First_chs:
Print "1st char invalid."
Return
For Ind,ch in Enumerate (myid[1:]):
If CH not in Other_chs:
print "Char in position:%s Invalid"% (Ind + 2)
Break
Else
Print "%s is valid"% myID
if __name__ = = ' __main__ ':
myID = Raw_input ("ID to check:")
If myID:
CHECK_ID (myID)
Else
Print "You must input an identifier."

Formatting operators

Strings can use formatting symbols to represent specific meanings

format character	convert
%c	Convert to characters
%s	first string conversion with STR () function
%d/%i	turn to signed decimal number
%o	Turn to unsigned octal
turn into scientific notation
%f/%f	turn into floating point number

>>> "%o"% 10
' 12 '
>>> "% #o"% 10
' 012 '
>>> "% #x"% 10
' 0xa '
>>> "%e"% 1000000
' 1.000000e+06 '

>>> "%f"% 3.1415
' 3.141500 '
>>> "%4.2f"% 3.1415
' 3.14 '

format operator auxiliary instruction	action
*	Define width or decimal precision (>>> "%*s%*s"% ( -8, ' name ', -5, ' age ') ' name    age  '
-	left justified
+
<SP>
#	Display 0 before octal number, ' 0 X ' or ' in front of hexadecimal number 0X '
0	The number displayed is preceded by 0 instead of the default Recognized spaces

>>> "My IP is:%s"% ' 192.168.1.1 '
' My IP is:192.168.1.1 '
>>> "My IP is: {}". Format (' 192.168.1.1 ')
' My IP is:192.168.1.1 '
>>> "My IP is:{},you IP is: {}". Format (' 192.1268.1.1 ', ' 172.40.1.1 ')
' My IP is:192.1268.1.1,you IP is:172.40.1.1 '
>>> "My IP is:{1},you IP is: {0}". Format (' 192.1268.1.1 ', ' 172.40.1.1 ')
' My IP is:172.40.1.1,you IP is:192.1268.1.1 '
Little Practice

1. Prompt user input (multi-line) data

2, assuming the screen width is 50, the user entered the multi-line data display (the text content is centered):

+********************************+

+ Hello World +

+ Great work! +

+********************************+ #!/usr/bin/env python

def get_contents ():
    Contents = []
    while True:
        data = Raw_input ("Enter to Quit") > ")
        if not data:
             Break
        contents.append (data)
     return contents

If __name__ = = ' __main__ ':
    width = off
    lines = get_contents ()
    print ' +%s+ '% (' * ' * width)
    for line in lines:
& nbsp;       Sp_wid,extra = divmod (Width-len (line)), 2)
         print "+%s%s%s+"% (' ' * sp_wid,line, ' * (Sp_wid + extra)
    print ' +%s+ '% (' * ' * width)

String templates

String templates provide a template object that can be used to implement the functionality of a string template

>>> Import Tab
>>> Import String
>>> origtxt = "Hi ${name}, I'll see you ${day}"
>>> t = string. Template (Origtxt)
>>> t.substitute (name = ' Bob ', day = ' tomorrow ')
' Hi Bob, I'll see you tomorrow '
>>> t.substitute (name = ' Tom ', day = ' The day after Tommorrow ')
' Hi Tom, I'll see you at Tommorrow '
Little Practice

Create user

1, write a program, realize the function of creating user

2. Prompt user to enter user name

3. Randomly generate 8-bit password

4. Create a user and set a password

5, e-mail notify users of relevant information

#!/usr/bin/env python

Import Sys
Import OS
Import Randpass2
Import string

Contents = "Username: ${username}
Password: ${password}
‘‘‘

t = string. Template (contents)

def adduser (user, passwd, email):
Os.system ("Useradd%s"%user)
Os.system ("Echo%s:%s | CHPASSWD "% (Passwd,user))
#os. System ("Echo%s | passwd--stdin%s "% (Passwd,user))
data = T.substitute (Username=user,password = passwd)
Os.system ("echo-e '%s ' | Mail-s ' user info '%s '% (Data,email))
if __name__ = = ' __main__ ':
Username = sys.argv[1]
PWD = Randpass2.gen_pass ()
AddUser (Username,pwd, "[email protected]")

Primitive string Operators

Built-in functions

This article is from the Linux server blog, so be sure to keep this source http://sailq21.blog.51cto.com/6111337/1858689

Python Learning Notes Day04-python strings, lists, tuples