一.基本操作

1.获取字符串长度

u = "www.google.com" 
print(len(u))
'''
14
'''

2.反转字符串

[1]字符串操作

str1='gooGle'
print(str1[::-1])
'''
elGoog
'''

[2]string–>list–>string [string join() 结合 list reverse()]

str1='gooGle'
list1=list(str1)
list1.reverse()
newstring= "".join(list1)
print(newstring)
'''
elGoog
'''

[3]str->list->str [string join() 结合 list s[::-1]取反

str1='gooGle'
list1=list(str1)
newstring= "".join(list1[::-1])
print(newstring)
'''
elGoog
'''

[4]reduce()

from functools import reduce
str1='gooGle'
result = reduce(lambda x,y:y+x,str1)
print(result)
'''
elGoog
'''

[5]栈

str1='gooGle'
l = list(str1) #模拟入栈
result = ""
while len(l)>0:
    result += l.pop() #模拟出栈
print(result)
'''
elGoog
'''

3.切片split()返回定义的变量

u = "www.google.com" 
u1,u2,u3 = u.split('.') 
print(u1)
print(u2)
print(u3)
'''
www
google
com
'''

4.切片split()返回list[不改变原string]

u='www.google.com'
l=u.split('.')
print(u)
print(l)
'''
www.google.com
['www', 'google', 'com']
'''

5.Python ASCII码与字符相互转换

#字符转ascii
u='A'
print(ord(u))
#ascii转字符
asc=65
print(chr(asc))
'''
65
A
'''

6.字符串大小写转换

str1='CXy'
print(str1.lower())
str1='gooGle'
print(str1.upper())
'''
cxy
GOOGLE
'''

7.判断字符串元素是否是数字，字母，数字或字母组合

str_1 = "123"
str_2 = "Abc"
str_3 = "123Abc"
print(str_1.isdigit()) #全为数字
print(str_2.isalpha()) #全为字母
print(str_3.isalnum()) #为字母或数字
'''
True
True
True
'''

二.新建string

三.删除string

1.string 去掉标点符号及空格

string = "Special $#! characters   spaces 888323"
a= ''.join(e for e in string if e.isalnum())
print(a)
'''
Specialcharactersspaces888323
'''

四.修改string

1.string repalce(old,new,max)lod替换为new,替换max个,不改变原string

u='google.gg'
result=u.replace('g','zn',3)
print(u)
print(result)
'''
google.gg
znooznle.zng
'''

五.在string中查找

1.string find(),index()返回第一个匹配项的索引 [若不存在匹配项，find()返回-1，index()会抛出异常]

u = "google"
print(u.find('g'))
print(u.index('g'))
print(u.find('z'))  #-1
# print(u.index('z')) #报错
#从字符串的末尾开始查找
print(u.rfind('g'))
print(u.rindex('g'))
print(u.rfind('z'))
# print(u.rindex('z'))#报错
'''
0
0
-1
3
3
-1
'''

2.string find()返回所有匹配项的索引组成的list

u = "www.google.com"
findelement='.'
a=[]
result=u.find(findelement,0)
print(result)
while result !=-1:
    a.append(result)
    result=u.find(findelement,result+1)
print(a)
'''
3
[3, 10]
'''

3.