[python] python基础

一、程序输出

#程序输出#1print 'hello world!'#2mystring = 'Welcome to the python world!'print mystring#3print "%s is number %d" % ("Python",1)#4myname = "WANG,Peng"myrank = 1print "%s is No.%d"%(myname,myrank)#5import sysprint >> sys.stderr,'Fatal error:invalid input!'#6logfile = open('e:/lab/test.txt','a')print >> logfile,'The information has been entered into the file.'logfile.close()

二、程序输入和raw_input()内建函数

#程序输入和raw_input()内建函数#1user = raw_input('Enter login name:')print 'Your login is ',user#2num = raw_input('Now enter a number:')print 'Doubing your number:%d' % (int(num)*2)

三、注释

#注释print 'Hello World!' #This is a comment

四、操作符

+ - * / // % **

五、变量和赋值

#变量和赋值counter = 0miles = 1000.0name = 'wangpeng'counter = counter+1kilometer = 1.609*filesprint '%f miles is the same as %f km.'%(miles,kilometer)

六、数字

有符号整型（长整型，布尔值），浮点值，复数

七、字符串

#字符串pystr = 'Python'iscool = 'is cool!'print pystr[0]print pystr[2:5]print iscool[3:]print iscool[-1]print pystr+iscoolprint pystr+' '+iscoolprint pystr*2print '_'*20pystr = 'python'+'\n'+'is cool'print pystr

八、列表和元组（只读列表）

#列表和元组（只读列表）#1aList = [1,2,3,4]#可以是不同类型的变量print aListprint aList[0]print aList[2:]print aList[:3]aList[1] = 5print aList#2aTuple = ('robots',77,93,'try')print aTupleprint aTuple[:3]aTuple[1] = 5 #errorprint aTuple

九、字典（由键+值对构成）

#字典（由键+值对构成）aDict = {'host':'earth'}#create a dictaDict['port'] = 80 #add to dictprint aDictprint aDict.keys()print aDict.values()print aDict['host']for key in aDict:print key,aDict[key]

十、代码块及缩进对齐

十一、if语句

#if语句number = 23guess = int(raw_input('Enter an integer:'))if guess==number:print 'Congratulation you guessed it.'print 'but you do not win any prize'elif guess < number:print 'No, it is a little higher than that.'else:print 'No, it is a little lower than that'print 'Done.'

十二、while循环

#while循环counter = 0while counter<3:print 'loop #%d'%(counter)counter += 1

十三、for循环和range()内建函数

#for循环和range()内建函数#1print 'I like to use the Internet for:'for item in ['e-mail','net-surfing','homework','chat']:print item#2print 'I like to use the Internet for:'print item #有，则四个项都在一行，否则各占一行。#3for eachNum in range(3):print eachNum#4foo = 'abc'for char in foo:print char#5foo = 'abc'for i in range(len(foo)):print foo[i],'(%d)'%i#6foo = 'abc'for i,ch in enumerate(foo):print ch,'(%d)'%i

十四、列表解析

#列表解析#1squared = [x**2 for x in range(4)]for i in squared:print i#2sqdEvens = [x**2 for x in range(8) if not x%2]for i in sqdEvens:print i

十五、文件和内建函数

#文件和内建函数#1filename = raw_input('Enter file name:')fobj = open(filename,'r')for eachLine in fobj:print eachLinefobj.close()#2filename = raw_input('Enter file name:')fobj = open(filename,'r')all_the_text = fobj.read()print all_the_textfobj.close()

十六、错误和异常

#错误和异常try:filename = raw_input('Enter file name:')fobj = open(filename,'r')for eachLine in fobj:print eachLine,#如果有，每行之间都没有一个空行，反之，打印出来的每行之间夹带着一个空行fobj.close()except IOError,e:print 'file open error:',e

十七、函数

#函数#1def addMe2Me(x):'apply plus operation to argument'return (x+x)print addMe2Me(4.25)print addMe2Me(10)print addMe2Me('python')print addMe2Me([-1,'abc'])#2def foo(debug=True):'determined in debug mode with default argument'if debug:print 'in debug mode'print 'dome'foo()foo(False)#3def myadd(a=0,b=0):'ADD OPERATION'c = int(a) + int(b)return cif __name__=="__main__":print myadd(2,3)print myadd()

十八、类

十九、模块

#模块import sys sys.stdout.write('Hello World!\n')print sys.platformprint sys.version