python数据类型之字符串部分内置函数

字符串的格式化

>>> CHA = 123
>>> a = 'test'
>>> print('My name is %s' % a)
My name is test
>>> print('I am %d years old'% CHA)
I am 123 years old

format_string % (string_to_convert1,string_to_convert2)

>>> 'My name is %s and I am %d years old' % (a,CHA)
'My name is test and I am 123 years old'

%s    将值转化为str()函数表达的字符串;
%d    将值转化为十进制数;
%c    将值转化为单个字符;
%r    将值转化为repr()函数表达的字符串;

字符串内置函数：

capitalize()    将字符串中第一个字符转换为大写

>>> a = 'hahah'
>>> a.capitalize()
'Hahah'

find('str')    检查字符串中是否包含str，找不到返回-1;

>>> a = 'My name is haha'
>>> a.find('name')
3
>>> a.find('my')
-1

index()        如果找不到返回异常

>>> a = 'My name is haha'
>>> a.index('name')
3
>>> a.index('my')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: substring not found

lower()        转换所有大写字符转换成小写

>>> a = 'MY NAME IS HAHA'
>>> a.lower()
'my name is haha'

title()        把字符串标题化,所有字符开头是大写的;

>>> a = 'my name is haha'
>>> a.title()
'My Name Is Haha'

istitle()    判断是否是标题化的字符串;

>>> a = a.title()
>>> a
'My Name Is Haha'
>>> a.istitle()
True

lstrip()    截掉字符串左边的空格;

>>> a = ' my name is haha'
>>> a
' my name is haha'
>>> a.lstrip()
'my name is haha'

replace('old','new')    替换操作;

>>> a = a.lstrip()
>>> a
'my name is haha'
>>> a.replace('haha','hello')
'my name is hello'

rstrip()    截掉字符串右边的空格;

>>> a = 'my name is hah '
>>> a
'my name is hah '
>>> a.rstrip()
'my name is hah'

split()        以str做分割字符串;

>>> a = 'zhangsan lisi wangye'
>>> a.split()
['zhangsan', 'lisi', 'wangye']