Python tutorial： python中文快速學習筆記 - 數字與字元串

3. python 數字與字元串

詞彙：

plus +

subtract -

mulitply *

division /

divisor 除數

reminder 餘數

power    ** 幂

equal  = 

fraction 小數部分

complex number  複數

decimal 十進制

parenthesis  圓括号

square parenthesis 方括号

brace  花括号

int integer 整數

float 浮點數

single quotes  ‘ ’

double quotes ” “

blackslash 、

raw string   r

triple-quotes ”“”   “”“

unicode  u

3.1 數字及運算

>>> 3 + 1
4
>>> 3 * (2 + 1)
9
>>> 7 / 2  # division
3
>>> 7 % 2  
1          # reminder
>>> 7.0 /  2  # float division
3.5
>>> 7.0 //  2
3.0
>>> 2**10  # power
1024
>>> price = 10
>>> tax = price * 12 / 100
>>> print price, tax
10 1
>>> print price + tax
<pre name="code" class="python" style="font-size: 18px;">11
           

内部變量 “_" 會預設獲得最後一個計算的值，被print函數引用的除外

>>> 2 + 3
5
>>> _
5
>>> a = 6
>>> a * 3
18
>>> _
18
>>> print a * 10
60
>>> _
18
>>>
           

3.2 字元

單引号與雙引号用法：

>>> 'spam eggs'  # single quotes
'spam eggs'
>>> 'doesn\'t'  # use \' to escape the single quote...
"doesn't"
>>> "doesn't"  # ...or use double quotes instead
"doesn't"
>>> '"Yes," he said.'
'"Yes," he said.'
>>> "\"Yes,\" he said."
'"Yes," he said.'
>>> '"Isn\'t," she said.'
'"Isn\'t," she said.'
           

raw string， 用r字元可以屏蔽掉特殊字元

>>> print 'C:\some\name'  # here \n means newline!
C:\some
ame
>>> print r'C:\some\name'  # note the r before the quote
C:\some\name
           

triple-quotes 可以讓一個字元串跨行

print """\
Usage: thingy [OPTIONS]
     -h                        Display this usage message
     -H hostname               Hostname to connect to
"""
           

字元串可以用加号來互相連接配接， 乘以數字實作重複次數

>>> 'a good' + ' day' + '!'*3
'a good day!!!'
           

字元串可以用分片的方式抽取部分或全部字元串。首個字元對應第0位。 word[<此位開始顯示:<顯示到此位以前>]

>>> word = 'agoodday'
>>> word[1:3]
'go'
           

>>> word[:3]
'ago'
>>> word[-2]
'a'
>>> word[-1]
'y'
           

len() 字元串的函數， 用來計算字元串長度

>>> len(word)
8
           

3.3. unicode 字元串

>>> current = u'￥'                                                                                             
>>> print current
￥                                                                                                                                                                     
>>> current.encode('utf-8')
'\xef\xbf\xa5'
>>>