python字符串的操作方法及实例

var1='Hello World!'
print (var1)

print('Hello World'*2)

print('Hello World'[2: ])

print('el' in 'Hello World')

print('alex is a good teacher')
print('%s is a good teacher' %'alex')

a ='123'
b='abc'
c=a+b
print(c)

c=''.join([a,b])
print(c)

s='asf sgs SD dfs ASdf'
print(s.capitalize())
>>Asf sgs sd dfs asdf

a='hello word'
print(a.upper())
b='HELLO WORD'
print(b.lower())
c='hello WORD'
print(c.swapcase())
>>HELLO WORD
>>hello word
>>HELLO word

s='     hello    '
b=s.strip()
print(b)
>>hello

s='     hello    '
b=s.ltrip()
c=s.rtrip()
print(b)
print(c)
>>hello
>>    hello

a='hello'
b=a*2
print(b)
>>hellohello

a='hello'
b='123'
a.join(b)
print(a.join(b))
>>1hello2hello3

a='hello word'
print(a.index('w'))
print(a.find('a'))
>>6
>>-1

a='hello word'
print('hello' in a)
print('hello' not in a)
>>True
>>False

a='hello word'
print(len (a))
>>10

a='chen zheng'
print(a.center(20,"*"))
>>*****chen zheng*****

#str.count()  统计字符串出现的次数
a='hello word'
print(a.count('l'))
>>2

#
S='prefix123aaasuffix'
print(S.startswith('prefix'))  #是否以prefix开头
print(S.endswith('suffix'))    #以suffix结尾
print(S.isalnum())             #是否全是字母和数字，并至少有一个字符
print(S.isalpha())             #是否全是字母，并至少有一个字符
print(S.isdigit())             #是否全是数字，并至少有一个字符
print(S.isspace())             #是否全是空白字符，并至少有一个字符
print(S.islower())             #S中的字母是否全是小写
print(S.isupper())             #S中的字母是否便是大写
print(S.istitle())             #S是否是首字母大写的