python笔记2

显示用户输入
user = raw_input('输入名字：') //raw_input是内建的函数
====>输入名字：root
print 'name is :',user===>name is :root

//int()字符串转数字
num = raw_input('')
1024
print '%d' % (int(num)*2)
2048

#为注释

符号：+，-，*，/。基本符号
//浮点除法，%取余，**乘方
比较运算符 >,>=,<,<=,==,!=
逻辑运算:and or not

数字类型：int,long,bool,float,complex
字符串：pystr='Python'
iscool = 'is cool!'
pystr[0]===>'P' //取第一个字符
pystr[2:5]===>'tho'  //取2--5的索引
iscool[:2]==>'is' //取从头到索引2
iscool[3:]==>'cool!'//取索引3到最后
iscool[-1]===>'!'  //取最后一位
pystr+iscool===>'Pythonis cool!'  //字符连接
pystr+' '+iscool==>'Python is cool!'
pystr*2===>'PythonPython'   //输出2遍
'_'*20===>'____________________' //输出20个_
pystr='''python
... is cool'''
pystr===>'python/nis cool'
print pystr====>python
is cool

数组和元数据
aList =[1,2,3,4]
aList===>[1,2,3,4]
aList[0]===>1
aList[2:]===>[3,4]
aList[:3]===>[1,2,3]
aList[1]=5
aList===>[1,5,3,4]

元组不能被修改
aTuple =('robots',77,93,'try')
aTuple===>('robots',77,93,'try')
aTuple[:3]==>('robots',77,93)
aTuple[1]=5    //出错

字典   //类似map
aDict = {'host':'earch'}
aDict['port'] = 80
aDict===>{'host':'earch','port':80}
aDict.keys()==>['host','port']
aDict['host']===>'earch'