Python ===if while for statement and a small web crawler instance

If branch statement

>>> count=89

>>> if count==89:

Print Count

#单分支

>>>

#coding: Utf-8

Count=int (raw_input (' Please enter a number '))

Print Count

If count>80:

print ' bigger than 80 '

Else

If count<80:

print ' smaller than 80 ' #多分支

======= Custom Function while if else===========

#coding: Utf-8

Count=int (raw_input (' Please enter a number '))

Print Count

If count>80:

print ' bigger than 80 '

Else

print ' smaller than 80 '

print ' End '

Sex=raw_input (' Please enter your gender ')

def inputsex (Sex):

while (sex!= ' Male ' and sex!= ' female '):

Print Sex

Sex=raw_input (' Please enter gender as male or female ')

If sex== ' Male ':

print ' gentleman! '

Else

If sex== ' female ':

print ' Lady '

Inputsex (Sex)

=====if else's relational expression bool judgment non 0 is true! =====

#coding: Utf-8

If True:

print ' 1True '

Else

print ' False '

If 0:

print ' 2True '

Else

print ' 2False '

If 1:

print ' 3True '

Else

print ' 3False '

If 298:

print ' 4True '

Else

print ' 4False '

If-2:

print ' 5True '

Else

print ' 5False '

1True

2False

3True

4True

5True

If

if (A and B):

if (A or B):

If not A:

=======================while Circulating Body ========================

======== crawler ======= of network Brush Browsing volume

#coding: Utf-8

Import time

Import WebBrowser

Import OS

Import Random

Count=random.ranint (2,8)

I=1

J=0

While J<count:

While i<=3:

Webbrowser.open_new_tab (' www.baidu.com ')

I=i+1

Time.sleep (3)

Else

Os.system (' taskkill/f/im iexplore.exe ')

J=j+1

Search the Internet when #windows下用taskkill.

#linux系统下用kill-pid or Killall Chrome

#ranint就是随机整数

=======for Loop Statement ============

For Val in Sth. Where Val does not have to be stated beforehand

For traversal string

#coding: Utf-8

s1= ' www.baidu.com '

I=0

For N in S1:

Print format (i, ' 2d '), n

I=i+1

Else

print ' Out for '

#format (i, ' 2d ') makes I a two output bit

For traversal list array

#coding: Utf-8

list1=[0,11,45, ' Dkfjah ', 12.5] list type

I=0

For Val in List1:

Print format (i, ' 2d '), Val

I=i+1

You can also write it directly

#coding: Utf-8

I=1

For Val in [11,23,0, ' dfadf ', ' Mandarin ', 12.45]:

Print format (i, ' 2d '), Val

I=i+1

Converts a string to a list list (str)

#coding: Utf-8

s1= ' www.baidu.com '

I=1

List1=list (S1)

Print List1

For Val in List1:

Print format (i, ' 2d '), Val

I=i+1

Tuple for traversal tuple tuple

#coding: Utf-8

#用圆括号括起来的是元组, the data in the tuple is read-only and cannot be modified.

tup= (1,2,3,4,5) tuple type

For T in Tup:

Print T

Else

print ' Out Tup '

For traversal file for Val in File.readlines ()

#coding: Utf-8

#如果所读的文件与此py程序文件所在地址一样, write the file name directly

For s in open (' 11.txt ', ' R '). ReadLine ():

Print S

Li3=open (' 11.txt ', ' R '). ReadLines ()

For a in open (' 11.txt ', ' R '). ReadLines ():

Open (' Tmp.txt ', ' A + '). Write (a) #a + is append write R Read W write w+ If no this file is first created and then written

Print a

Print Len (LI3)

How long is the #len (li3) output list here that's how many lines the article has

#readline () returns a string that returns the first row by default

#readlines () returns the list default to all rows in the file

#用help (file.readline) View Help

Python ===if while for statement and a small web crawler instance