Python基础-Python字符串处理的十个小规则_python字符串规则-优快云博客

本文链接：https://blog.youkuaiyun.com/cxyxx12/article/details/132287066

字符串处理在日常Python编程中是用的比较多的操作。这里列一下Python字符串处理的一些实用技巧和使用方式，避免踩坑。

1.双引号与单引号

Python中定义字符串时，单引号和双引号是有区别的：

对于没有特殊字符的，双引号和单引号都一样：

>>> "Hello,world!"``'Hello,world!'``>>> 'Hello,world!'``'Hello,world!'

对于字符串内容带特殊标点和字符的，就需要注意了

>>> "'Nic' is s student"``"'Nic' is s student"``>>> ''Nic' is s student'`  `File "", line 1`    `''Nic' is s student'`        `^``SyntaxError: invalid syntax``>>> '"Nic" is s student'``'"Nic" is s student'

2.转义符

双引号就不需要转义

>>> "Let's go!"``"Let's go!"

单引号，则需要转义:

>>> 'Let's go!'`  `File "", line 1`    `'Let's go!'`         `^``SyntaxError: invalid syntax

>>> 'Let\'s go!'``"Let's go!"

双引号转义

>>> "\"Hello World!\" she said"``'"Hello World!" she said'

3.连接字符串

将2个字符串连接起来：

直接连起来写

用双引号：

>>> "Hello" "World"``'HelloWorld'`          `   ``>>> "Let's say" '"Hello World!"'``'Let\'s say"Hello World!"'`          `   ``>>> "Let\'s say" '"Hello World!"'``'Let\'s say"Hello World!"'

注意看上面的，Python打印的字符串还是被引号括起来，并加了转义符

–需要使用print打印

>>> print "Let's say" '"Hello World!"'``Let's say"Hello World!"`          `   ``>>> print "Let\'s say" '"Hello World!"'``Let's say"Hello World!"

4.变量连接

>>> x="Hello"``>>> y="World"

这样连接会报错：

>>> x y`  `File "", line 1`    `x y`      `^``SyntaxError: invalid syntax

这样也不行：

>>> x-y``Traceback (most recent call last):`  `File "", line 1, in``TypeError: unsupported operand type(s) for -: 'str' and 'str'

要使用+号

>>> x+y``'HelloWorld'

中间加空格

>>> x+" "+y``'Hello World'

5.str与repr

将值转换为字符串

str函数–把值转换为合理形式的字符串

repr函数创建一个字符串，以合法的Python表达式的形式表示值

对比二者的区别

>>> print repr("Hello, World!")``'Hello, World!'`          `   ``>>> print repr(10000L)``10000L`          `   ``>>> print str("Hello, World!")``Hello, World!`          `   ``>>> print str(10000L)``10000

repr也可以用反引号实现

>>> temp=37``>>> print temp``37

>>> print "Temp is " + temp``Traceback (most recent call last):`  `File "", line 1, in``TypeError: cannot concatenate 'str' and 'int' objects

单引号引用还是字符串内容：

>>> print "Temp is " + 'temp'``Temp is temp

反引号才能引用到变量值

` >>> print "Temp is " + `temp` ```Temp is 37

6.键盘输入raw_input与input

>>> input ("Enter a number: ")``Enter a number: 100``100

>>> raw_input ("Enter a number: ")``Enter a number: 100``'100'

>>> name = input("What's your name? ")``What's your name? Jim``Traceback (most recent call last):`  `File "", line 1, in`  `File "", line 1, in``NameError: name 'Jim' is not defined

>>> name = raw_input("What's your name? ")``What's your name? jim``>>> print name``jim

区别看出来了吗？raw_input函数将所有的输入当做原始数据将其放入字符串中

7.使用三引号跨行

直接换行会报错：

>>> print "Hello #敲回车报错`  `File "", line 1`    `print "Hello`               `^``SyntaxError: EOL while scanning single-quoted string

可以使用三引号：

>>> print '''Hello``... World,``... Hello,``... Jim.``... over!'''``Hello``World,``Hello,``Jim.``over!

一个小例子

def hello(): print 'i am test3' if name == ‘main’: a=10 b=‘’'hello hello2 hello3 hello4''' print b

D:\Python27\python.exe D:/sync/asp_notes_all/python/tuji/lesson01/test/testTT3.py``hello`    `hello2`    `hello3`    `hello4``Process finished with exit code 0

8.使用斜线跨行

>>> print "Hello,\``... World!"``Hello,World!`          `   ``>>> print \``... 'Hello World'``Hello World`          `   ``>>> print \``... "Hello World"``Hello World`          `   ``>>> 1+2+ \``... 3``6

9 \n换行

>>> path = 'C:\note'``>>> path``'C:\note'``>>> print path``C:``ote

>>> path = 'C:\\note'``>>> path``'C:\\note'``>>> print path``C:\note

10 引用原始字符串

但是如果要转义的很多，就有点繁琐–引出原始字符串的用途

`>>> print r'Let\'s go!'``Let\'s go!`          `   ``>>> print r'C\note'``C\note`          `   ``>>> print r'C:\note'``C:\note`          `   ``>>> print r'D:\1-abseedb\sync_docs_dba\asp-db'``D:\1-abseedb\sync_docs_dba\asp-db`

原始字符串最后一个不能是反斜线

>>> print r'C:\note'``C:\note`          `   ``>>> print r'C:\note\'`  `File "", line 1`    `print r'C:\note\'`                    `^``SyntaxError: EOL while scanning single-quoted string

解决办法：