字符串类型

二、字符串类型

# ======================================基本使用======================================
# 1、用途:记录名字\性别等描述性质

# 2、定义方式:在''\""\""" """\''' '''内包含一系列的字符
# name='kevin' # name=str('kevin')

# 数据类型转换：str可以将任意类型都转成字符串类型
# n=str([1,2,3]) #'[1,2,3]'
# print(type(n))

# 3、常用操作+内置的方法
#3.1 优先掌握的操作*****：
#1、按索引取值(正向取+反向取) ：只能取
# msg='hello world'
# print(msg[0])
# print(msg[-1])

# msg[0]='A'

#2、切片(顾头不顾尾，步长):从一个大的字符串中切出一个小字符串
# msg='hello world'
# print(msg[0:5:1])
# print(msg[0:5:2]) #0 2 4

# info='egon 18'
# print(info[0:4])

# 了解
# msg='hello world'
# print(msg[-1:-12:-1]) #-1 -2 -3 -4
# print(msg[-1::-1]) #-1 -2 -3 -4
# print(msg[::-1]) #-1 -2 -3 -4

#3、长度len
# print(len('ad你好'))

#4、成员运算in和not in：判断一个子字符串是否存在于一个大字符串中
# msg='name age sex'
# print('sex' in msg)
# print('sex' not in msg)

#5、移除空白strip：移除字符串左右两边的字符
# msg='*****egon****************'
# res=msg.strip('*')
# print(res)

# msg='     egon  '
# print(msg.strip())

# msg='+-*&^%egon-=)^(#'
# print(msg.strip('-+*&^%(#='))

# name=input('name>>>: ').strip()
# pwd=input('pwd>>>:').strip()
# if name == 'egon' and pwd == '123':
#     print('login successful')
# else:
#     print('user or pwd error')


#6、切分split:把一个字符串按照某种分隔符切成一个列表，从而方便取值
# info='egon:18:male'
# res=info.split(':')
# print(res[0])
# print(res)
# info1=res[0]+':'+res[1]+':'+res[2]
# info1=':'.join(res) #res中所有的元素必须是str类型
# print(info1)

# cmd='get|a.txt|131123123'

# print(cmd.split('|'))

#7、循环
# msg='hello'
# for item in msg:
#     print(item)


# 3.2 需要掌握的操作****
#1、strip,lstrip,rstrip
# print('****egon***'.strip('*'))
# print('****egon***'.lstrip('*'))
# print('****egon***'.rstrip('*'))
#2、lower,upper
# print('AdaEs1'.lower())
# print('AdaEs1'.upper())

#3、startswith,endswith
# print('alex is dsb'.startswith('alex'))
# print('alex is dsb'.startswith('al'))
# print('alex is dsb'.endswith('sb'))=

#4、format的三种玩法
# msg='my name is %s my age is %s' %('egon',18)
# print(msg)

# msg='my name is {name} my age is {age}'.format(age=18,name='egon')
# print(msg)

# 了解
# msg='my name is {} my age is {}'.format('egon',18)#这种要按顺序输入
# print(msg)

# msg='my name is {1}{0}{0}{0} my age is {1}{1}'.format('egon',18)
# print(msg)

#5、split,rsplit
# info='egon:18:male'
# print(info.split(':',1))
# print(info.rsplit(':',1))

#6、replace
# msg='kevin is dsb kevin'
# res=msg.replace('kevin','dsb',1)
# print(res)

#7、isdigit:当字符串是由纯数字组成时返回True
# print('123123'.isdigit())

# age_of_db=18
# inp_age=input('>>: ').strip()
# if inp_age.isdigit():
#     inp_age=int(inp_age)
#     print(inp_age == age_of_db)
# else:
#     print('年龄必须是数字')

# 3.3 了解的操作
#1、find,rfind,index,rindex,count
# find: 查找子字符串在大字符串中的起始位置
# msg='kevin is kevin xxxx sb'
# print(msg.find('kevin'))
# print(msg.index('kevin'))
# print(msg.find('asdf'))
# print(msg.index('asdf'))

# print(msg.rfind('kevin'))

# count:统计子字符串在大字符串中出现的次数
# print('alex kevin alex kevin kevin'.count('kevin'))

#2、center,ljust,rjust,zfill
# username=input('>>>: ').strip()
# print(username.center(50,'*'))

# print('egon'.ljust(50,'#'))
# print('egon'.rjust(50,'#'))

# print('egon'.rjust(50,'0'))
# print('egon'.zfill(50))

#3、captalize,swapcase,title
# print('abdef adsfasdf'.capitalize())
# print('AbC'.swapcase())
# print('my name is egon'.title())

#4、is数字系列
# print('123213'.isdigit())
# print('Ⅳ'.isnumeric())
# print('贰'.isnumeric())
#5、is其他
# name='My Nmae'
# print(name.isalnum()) #字符串由字母或数字组成
# print(name.isalpha()) #字符串只由字母组成

# print(name.isidentifier())
# print(name.islower())
# print(name.isupper())
# print(name.isspace())
# print(name.istitle())

# ======================================该类型总结====================================
# 存一个值

# 有序

# 不可变（1、可变：值变，id不变。可变==不可hash 2、不可变：值变，id就变。不可变==可hash）
# x='a'
# print(id(x))
# x+='b'
# # print(x)
# print(id(x))