Python中的运算符、数据类型、字符串及列表操作举例
1.运算符
(1)算术运算符:
(2)关系运算符:
(3)赋值运算符:
(4)逻辑运算符:
优先级:() > not > and > or
2.数据类型:
raw_input(): 接收字符串类型
input() : 接收数字类型
整型:
a =-100
abs(a) 求a的绝对值
a.__abs__() 求a的绝对值
符点型:
round()方法 默认保留1位小数,采用四舍五入方法进行计算,最后一位为偶数.
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a = 3.0
round (a)
round ( 2 )
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先进行四舍五入运算,如果小数点精度的最后一位是偶数符合条件,如果小数点精度最后一位四舍五入以后为奇数,则舍弃小说点精度以后所有数字,以保证小数点精度,最后一位为偶数
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c = 2.555
d = 1.545
print ( round (c, 2 ))
print ( round (d, 2 ))
2.56
1.54
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布尔类型:
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True
False
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3.字符串
dir()查看有哪些内置方法
type()查看是什么类型
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str1 = 'aaaaabasdfxqs353235asdf'
print (str1.find( 'fxq' ))
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str1 = 'aaaaabasdfxqs353235asdf'
print (str1.replace( 'fxq' , 'Fengxiaoqing' ))
aaaaabasdFengxiaoqings353235asdf
str1 = 'aaaaabasdfxqs353235asdf'
print (str1.split( 's' ))
[ 'aaaaaba' , 'dfxq' , '353235a' , 'df' ]
str1 = 'aaaaabasdfxqs353235asdf'
print ( 'SSS' .join(str1.split( 's' )))
aaaaabaSSSdfxqSSS353235aSSSdf
a = ' aaaaaba sdfx qs353 235asdf '
print (a.strip())
print (a)
print (a.lstrip()) #去掉左边空格
print (a.rstrip()) #去掉右边空格
aaaaaba sdfx qs353 235asdf
aaaaaba sdfx qs353 235asdf aaaaaba sdfx qs353 235asdf aaaaaba sdfx qs353 235asdf
format ()方法:
name = 'fengxiaoqing'
age = 30
home = 'chengde'
print ( 'hello' + name)
print ( 'hello {0}' ). format (name)
print ( 'hello %s' ) % name
print ( 'hello %d' ) % age
print ( '我的年龄是:{0} 我的家:{1}' ). format (age,home)
print ( '{name}:{age}' . format (name = 'fxq' ,age = 20 ))
hellofengxiaoqing
hello fengxiaoqing
hello fengxiaoqing
hello 30
我的年龄是: 30 我的家:chengde
fxq: 20
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4.list操作
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'append' , 'count' , 'extend' , 'index' , 'insert' , 'pop' , 'remove' , 'reverse' , 'sort'
str1 = '12poqiwrtgopwert'
str2 = list (str1)
print ( type (str1))
print ( type (str2))
print ( list (str1))
print ( dir (str2))
print ( '####' * 20 )
a = [ 123 , 'bbb' , 'ace' ]
print (a[ 1 ])
print (a.index( 'bbb' ))
a.insert( 1 , 'aaa' )
print (a)
a.sort()
print (a)
a.reverse()
print (a)
a.append( 'ooo' )
print (a)
a.pop()
print (a)
a.remove( 123 )
print (a)
a.pop( 1 )
print (a)
< type 'str' >
< type 'list' >
[ '1' , '2' , 'p' , 'o' , 'q' , 'i' , 'w' , 'r' , 't' , 'g' , 'o' , 'p' , 'w' , 'e' , 'r' , 't' ]
[ '__add__' , '__class__' , '__contains__' , '__delattr__' , '__delitem__' , '__delslice__' , '__doc__' , '__eq__' , '__format__' , '__ge__' , '__getattribute__' , '__getitem__' , '__getslice__' , '__gt__' , '__hash__' , '__iadd__' , '__imul__' , '__init__' , '__iter__' , '__le__' , '__len__' , '__lt__' , '__mul__' , '__ne__' , '__new__' , '__reduce__' , '__reduce_ex__' , '__repr__' , '__reversed__' , '__rmul__' , '__setattr__' , '__setitem__' , '__setslice__' , '__sizeof__' , '__str__' , '__subclasshook__' , 'append' , 'count' , 'extend' , 'index' , 'insert' , 'pop' , 'remove' , 'reverse' , 'sort' ]
################################################################################
bbb
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[ 123 , 'aaa' , 'bbb' , 'ace' ]
[ 123 , 'aaa' , 'ace' , 'bbb' ]
[ 'bbb' , 'ace' , 'aaa' , 123 ]
[ 123 , 'aaa' , 'ace' , 'bbb' , 'ooo' ]
[ 123 , 'aaa' , 'ace' , 'bbb' ]
[ 'aaa' , 'ace' , 'bbb' ]
[ 'aaa' , 'bbb' ]
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列表切片:
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a = [ 11 , '222' , '33' , 444 , 555 , 666 ]
print (a[ 3 :])
print (a[ 1 : 5 ])
print (a[ 1 : 6 : 2 ])
print (a[: 4 ])
print (a[ - 1 ])
print (a[ - 2 :])
print (a[ - 4 : - 2 ])
[ 444 , 555 , 666 ]
[ '222' , '33' , 444 , 555 ]
[ '222' , 444 , 666 ]
[ 11 , '222' , '33' , 444 ]
666
[ 555 , 666 ]
[ '33' , 444 ]
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本文转自 枫叶云 51CTO博客,原文链接:http://blog.51cto.com/fengyunshan911/2063040