Python开发（一）
- 2020 年 1 月 13 日
- 筆記
python
>>> s='tou siheoiw' >>> '%s is number %d' % (s[:6],1) 'tou si is number 1'
>>> hi='''hi there''' >>> hi 'hinthere'
>>> 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']
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。未完待续
