「Python」字符串操作

>>> s1 = 'hello, world!'
>>> s2 = "hello, world!"
>>> s3 = """	
hello, 
world!
"""
>>> print(s1, s2, s3, end='')
hello, world! hello, world! 
hello, 
world!
>>> s4 = """ my     # 以三个双引号或单引号开头的字符串可以换行
name
is
axyzdong
"""
>>> print(s4)
 my
name
is
axyzdong

>>> print(r'my name is axyzdong \n')
my name is axyzdong \n
>>> print('my name is \n axyzdong ')
my name is 
 axyzdong

>>> spam = 'Hello world!'
>>> spam[0]
'H'
>>> spam[-1]
'!'
>>> spam[0:1]
'H'
>>> spam[0:2]
'He'
>>> spam[:5]
'Hello'
>>> spam[6:]
'world!'

>>> 'Hello' in 'Hello world!'
True
>>> 'hello' in 'Hello world!' #大小写有区别
False
>>> 'world' in 'Hello world!'
True
>>> 'my' in 'Hello world!'
False

>>> spam1 = 'hello world!'
>>> print(len(spam1))	#获取字符串长度
12
>>> print(spam1.capitalize ())	#字符串字母大写拷贝
Hello world!
>>> print(spam1.title ())	#每个单词首字母大写拷贝
Hello World!
>>> print(spam1.upper ())	#字符串变大写后的拷贝
HELLO WORLD!
>>> print(spam1.find ('world'))	#查找字符串所在的位置
6
>>> print(spam1.startswith ('he'))	#检查字符串是否以特定的字符串开头
True
>>> print(spam1.startswith ('He'))
False
>>> print(spam1.endswith ('he'))	#检查字符串是否以特定的字符串结尾
False
>>> print(spam1.endswith ('!'))
True
>>> print(spam1.center (20,'*'))	#将字符串以指定的宽度居中并在两侧填充指定的字符
****hello world!****
>>> print(spam1.rjust (20,' '))	#将字符串以指定的宽度靠右放置左侧填充指定的字符
        hello world!    
>>> spam2 = '123abc'
>>> print(spam2.isdigit ())	#检查字符串是否全由数字构成
False
>>> print(spam2.isalpha ())	#检查字符串是否全由字母构成
False
>>> print(spam2.isalnum ())	#检查字符串是否由数字和字母构成
True
>>> spam3 = '  axyzdong@qq.com   '	#获得字符串左右两侧空格之后的拷贝
>>> print(spam3.strip ())
axyzdong@qq.com
>>> print(spam3)
  axyzdong@qq.com

>>> a, b = 1,2
>>> print('%d + %d = %d'% (a,b,a+b))
1 + 2 = 3
>>> print(f'{a} + {b} = {a+b}')	#Python3.6后简洁的格式化方式
1 + 2 = 3

>>> import pyperclip
>>> pyperclip.copy ('Hello world!')
>>> pyperclip.paste ()
'pyperclip