Python学习笔记3-字符串
格式化字符串／复合字段名>>> import humansize
>>> si_suffixes = humansize.SUFFIXES
>>> si_suffixes
['KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB']
>>> '1000{0} = 1{0}'.format(si_suffixes)
'1000KB = 1MB'
>>> import humansize
>>> import sys
>>> '1MB = 1000{0.modules.SUFFIXES}'.format(sys)
'1MB = 1000KB'
Sys.modules 是一个保存当前python实例中搜有已导入模块的字典。模块的名字为键，模块自身为值。
>>> s = '''finished files are the re-
sults of years of scientific study combined with the
experience of years. ‘''
>>> s.splitlines()
['finished files are the re-', 'sults of years of scientific study combined with the', 'experience of years. ‘]
>>> print(s.lower())
finished files are the re-
sults of years of scientific study combined with the
experience of years.
>>> a_list = query.split("&")
>>> a_list
['user=pilgrim', 'database=master', ‘password=PapayaWhip']
>>> a_list_of_list =
>>> a_list_of_list
[['user', 'pilgrim'], ['database', 'master'], ['password', ‘PapayaWhip']]
>>> a_dict = dict(a_list_of_list)
>>> a_dict
{'password': 'PapayaWhip', 'database': 'master', 'user': ‘pilgrim'}
split()－根据指定的分隔符，将字符串分隔成一个字符串列表。
dict() － 将包含列表的列表转换成字典对象
字符串的分片
>>> a_string = "My alphabet starts where your alphabet ends."
>>> a_string
‘alphabet'
>>> a_string
'alphabet starts where your alphabet en’
>>> a_string[:18]
'My alphabet starts’
>>> a_string
' where your alphabet ends.'
String VS. Bytes
Bytes对象的定义：b’ ’, eg: by = b’abcd\x65’
Bytes对象不能改变其值，但可以通过内置函数bytearry()将bytes对象转化成bytearry对象，bytearry对象的值可改变
>>> by = b'abcd\x65'
>>> barr = bytearray(by)
>>> barr
bytearray(b'abcde')
>>> barr=102
>>> barr
bytearray(b'fbcde')
>>> a_string = "dive into python"
>>> by = a_string.encode('utf-8')
>>> by
b'dive into python'
>>> roundtrip = by.decode('big5')
>>> roundtrip
'dive into python'
string.encode() -- 使用某种编码方式作为参数，将字符串转化为bytes对象。
bytes.decode() -- 使用某种编码方式作为参数，将bytes对象转化成字符串对象。
页:
[1]