Python开发（一）

py3study

发布于 2020-01-13 15:29:03

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发布于 2020-01-13 15:29:03

文章被收录于专栏：python3python3

python

>>> s='tou siheoiw'
>>> '%s is number %d' % (s[:6],1)
'tou si is number 1'

>>> hi='''hi
there'''
>>> hi
'hi\nthere'

>>> book ={'title':'Python Web Development','year':2008}
>>> book
{'year': 2008, 'title': 'Python Web Development'}
>>> 'year' in book
True
>>> 'pub' in book
False

setdefault和get一样，dict.get(key)或是dict[key]

>>> d ={'title':'Python Web Development','year':2008}
>>> d
{'year': 2008, 'title': 'Python Web Development'}
>>> d.setdefault('pub','Addison Wesley')
'Addison Wesley'
>>> d
{'year': 2008, 'pub': 'Addison Wesley', 'title': 'Python Web Development'}
>>> del d['pub']
>>> d
{'year': 2008, 'title': 'Python Web Development'}
>>> d['title']
'Python Web Development'
>>> len(d)
2

while循环：

>>> while i<5:
...     print i
...     i +=1
...    
... 
0
1
2
3
4

建一个文本

#!/bin/bash
#4.4.sh
i=$[ $1 % 2]
if test $i -eq  0 ; then
   echo oushu
else
   echo jishu
fi
~

>>> for line in open('4.sh'):
...     if 'jishu' in line:  
...         print line
... 
   echo jishu

>>> for line in open('4.sh'):
...     print line
... 
#!/bin/bash

#4.4.sh

i=$[ $1 % 2]

if test $i -eq  0 ; then

   echo oushu

else 

   echo jishu

fi

enumerate是一个能让你同时迭代和计数的内置函数

>>> data =(123,'abc',3.14)
>>> for i, value in enumerate(data):
...     print i,value
... 
0 123
1 abc
2 3.14

简单的计算

#!/usr/bin/python
#filename:expression.py
length=5
breadth=2
area=length*breadth
print 'Area is',area
print 'Perimeter is',2*(length+breadth)
                                                                            
"expression.py" [New] 7L, 142C written

# python expression.py
Area is 10
Perimeter is 14

输入转化为×××：int(raw_input(''))

#!/usr/bin/python
#Filename:if.py
number=23
guess=int(raw_input('Enter an integer:'))
if guess==number:
    print 'Congratulations,u guessed it.'
    print "(but u do not w in any prizes!)"
elif guess< number:
    print 'No ,it is a little higher than that'
else:
    print 'No,it is a little lower than that'
                                                                           
~                                                                               
"if.py" [New] 12L, 311C written
# python if.py
Enter an integer:78
No,it is a little lower than that

continue：

有关计算字符串长度len(s)

#!/usr/bin/python
#Filename:continue.py
while True:
    s=raw_input('Enter something:')
    if s=='quit':
        break
    if len(s)<3:
        continue
    print 'Input is of sufficient length'
~                                                                               
                                                                             
~                                                                               
"continue.py" 9L, 196C written                                
# python continue.py
Enter something:77
Enter something:e
Enter something:3
Enter something:eee
Input is of sufficient length
Enter something:
Enter something:quit
#

定义函数

def 函数名（）：

函数体

函数名（）看见没那么快，

 #!/usr/bin/python
#filename:func_param.py
def printMax(a,b):
    if a>b:
        print a,'is maximum'
    else:
        print b,'is maximum'
printMax(3,4)

                                                                            
~                                                                               
"func_param.py" [New] 9L, 156C written                        

# python func_param.py
4 is maximum

局部变量：

#!/usr/bin/python
#filename:func_local.py
def func(x):
    print 'x is',x
    x=2
    print 'Changed localx to',x

x=50 
func(x)
print 'x is still',x
~                                                                               
                                                                             
"func_local.py" 10L, 152C written                             
# python func_local.py
x is 50
Changed localx to 2
x is still 50

全局变量：

#!/usr/bin/python
#Filename:func_global.py
def func():
    global x
    print 'x is',x
    x=2
    print 'Changed local x to',x
x=50
func()
print 'Value of x is',x
                                                                            
~                                                                               
"func_global.py" [New] 10L, 164C written                      
# python func_global.py
x is 50
Changed local x to 2
Value of x is 2

定义函数的默认参数：

#!/usr/bin/python
#Filename:func_default.py
def say(message,times=1):
    print message*times
say('Hello')
say('World',5)
~                                                                               
                                                                            
"func_default.py" [New] 6L, 122C written                      
# python func_default.py
Hello
WorldWorldWorldWorldWorld

关键参数：

#!/usr/bin/python
#filename:func_key.py
def func(a,b=5,c=10):
    print 'a is',a,'and b is',b,'and c is',c

func(3,7)
func(25,c=24)
func(c=50,a=100)
~                                                                               
                                                                             
"func_key.py" [New] 8L, 149C written                          
# python func_key.py
a is 3 and b is 7 and c is 10
a is 25 and b is 5 and c is 24
a is 100 and b is 5 and c is 50

return语句

#!/usr/bin/python
def returnn(a,b):
    if a>b:
        return a
    else:
        return b
print returnn(2,4)
~                                                                                                                                                             
~                                                                               
"return.py" 7L, 111C written                                  
# python return.py 
4

def printMax(x,y):
#!/usr/bin/python
def printMax(x,y):
    x=int(x)#convert to integers,if possible
    y=int(y)

    if x>y:
        print x,'is maximum'
    else:
        print y,'is maximum'
printMax(3,5)
print printMax.__doc__ 
                                                                              
~                                                                               
"func_doc.py" 11L, 214C written
# python func_doc.py
5 is maximum
None

sys模块：

模块是包含了你定义的所有的函数和变量的文件

#!/usr/bin/python
#Filename:using_sys.py
import sys
print 'The com m and line arguments are:'
for i in sys.argv:
    print i
print '\n',sys.path,'\n'
~

# python using_sys.py we are arguments
The com m and line arguments are:
using_sys.py
we
are
arguments

['/root',
 '/usr/lib64/python26.zip', '/usr/lib64/python2.6', 
'/usr/lib64/python2.6/plat-linux2', '/usr/lib64/python2.6/lib-tk', 
'/usr/lib64/python2.6/lib-old', '/usr/lib64/python2.6/lib-dynload', 
'/usr/lib64/python2.6/site-packages', 
'/usr/lib/python2.6/site-packages']

其中：using_sys.py 是sys.argv[0]

we 是 sys.argv[1]

are 是sys.argv[2]

arguments是sys.argv[3]

字节编译的.pyc文件

模块的__name__

#!/usr/bin/python
#filename 
if __name__=='__main__':
    print 'This program is being run by itself'
else:
    print 'I am being imported from another module'
                                                                             
~                                                                               
"using_name.py" [New] 7L, 161C written                        
[root@10-8-11-204 ~]# python using_name.py
This program is being run by itself
[root@10-8-11-204 ~]# python
Python 2.6.6 (r266:84292, Nov 22 2013, 12:16:22) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import using_name
I am being imported from another module

创建字节的模块

#!/usr/bin/python
import mymodule
mymodule.sayhi()
print 'Version',mymodule.version
~                                                                                                                                                             
"mymodule_demo.py" [New] 4L, 84C written                      
[root@ ~]# python mymodule_demo.py
Hi,this is mymodule speaking
Version 0.1

from...import

from mymodule import sayhi,version

(sayhi,version是mymodule的方法和变量)

#!/usr/bin/python
#filename
from mymodule import sayhi,version
sayhi()
print 'Version',version
~                                                                             
"mymodule_demo2.py" [New] 5L, 95C written
[root@ ~]# python mymodule_demo2.py
Hi,this is mymodule speaking
Version 0.1

dir()函数

[root@ ~]# python
Python 2.6.6 (r266:84292, Nov 22 2013, 12:16:22) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> dir(sys) 
['__displayhook__', '__doc__', '__excepthook__', '__name__', '__package__', '__stderr__', '__stdin__', '__stdout__', '_clear_type_cache', '_current_frames', '_getframe', 'api_version', 'argv', 'builtin_module_names', 'byteorder', 'call_tracing', 'callstats', 'copyright', 'displayhook', 'dont_write_bytecode', 'exc_clear', 'exc_info', 'exc_type', 'excepthook', 'exec_prefix', 'executable', 'exit', 'flags', 'float_info', 'getcheckinterval', 'getdefaultencoding', 'getdlopenflags', 'getfilesystemencoding', 'getprofile', 'getrecursionlimit', 'getrefcount', 'getsizeof', 'gettrace', 'hexversion', 'maxint', 'maxsize', 'maxunicode', 'meta_path', 'modules', 'path', 'path_hooks', 'path_importer_cache', 'platform', 'prefix', 'ps1', 'ps2', 'py3kwarning', 'setcheckinterval', 'setdlopenflags', 'setprofile', 'setrecursionlimit', 'settrace', 'stderr', 'stdin', 'stdout', 'subversion', 'version', 'version_info', 'warnoptions']

。

。未完待续

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原始发表：2019-08-13 ，如有侵权请联系 cloudcommunity@tencent.com 删除

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