DAY02

字符串

定义：在单引号双引号三引号内，由一串字符组成

name='PatHoo' #本质为 name=str('PatHoo')

常用方法：

索引

name='PatHoo'
print(name[0])
>>> P
print(name[1000])
>>> #IndexError: string index out of range

移除(默认移除空格)

name=input('username: ').strip()
print(name)

name='***PatHoo********'
print(name.strip('*'))
>>> PatHoo
print(name.lstrip('*'))
>>> PatHoo********
print(name.rstrip('*'))
>>> ***PatHoo

切分(默认按空格切分)

user_info='root:x:0:0::/root:/bin/bash'
print(user_info.split(':')[5])
>>> /root
cmd_info='get|a.txt|333333333'
print(cmd_info.split('|')[0])
>>> get
print(cmd_info.split('|',1)) #切分一次
>>> ['get', 'a.txt|333333333']
msg='name PatHoo age 18'
print(msg.split())
>>> ['name', 'PatHoo', 'age', '18']

取长度

name='PatHoo'
print(name.__len__())
>>> 6
print(len(name)) #name.__len__()
>>> 6

切出子字符串

name='hello world'
print(name[1])  #下标从0开始
>>> e
3 print(name[1:7]) #不包含末尾的下标
>>> ello w
print(name[1:7:3]) #每隔2个字符
>>> eo

字符的其他方法(掌握)

name='Patrick Hoo'
print(name.endswith('oo'))
>>> True
print(name.startswith('P'))
>>> True

name='PatHoo say: i have a dream, my name is PatHoo.'
print(name.replace('PatHoo','VIMMER',1))
>>> VIMMER say: i have a dream, my name is PatHoo.

print('{} {} {}'.format('PatHoo',18,'male'))
>>> PatHoo 18 male
print('{0} {1} {0}'.format('PatHoo',18,'male'))
>>> PatHoo 18 PatHoo
print('NAME:{name} AGE:{age} SEX:{sex}'.format(age=18,sex='male',name='PatHoo'))
>>> NAME:PatHoo AGE:18 SEX:male

num='123'
print(num.isdigit())
>>> True

while True:
    age=input('>>: ').strip()
    if len(age) == 0:continue
    if age.isdigit():
        age=int(age)
        print(age,type(age))

字符其他需要了解的方法

name='PatHoo hello'
print(name.find('o')) #找到则显示第一个字符的下标
>>> 4
print(name.find('x')) #没找到显示-1, 不报错
>>> -1
print(name.find('l',8,11)) #按范围查找
>>> 9
print(name.index('o')) #找到则显示第一个字符的下标
>>> 4
print(name.index('x')) #没找到报错
>>> ValueError: substring not found

name='PatHoo hello'
print(name.count('o',3,6))
>>> 2

L=['PatHoo','say','hello','world'] #用join方法拼接, 列表内容必须都是字符串
print(':'.join(L))
>>> PatHoo:say:hello:world

name='PatHoo'
print(name.center(30,'*'))
>>> ************PatHoo************
print(name.ljust(30,'*'))
>>> PatHoo************************
print(name.rjust(30,'*'))
>>> ************************PatHoo
print(name.zfill(30))
>>> 000000000000000000000000PatHoo

name='PatHoo	hello'
print(name)
>>> PatHoo    hello
print(name.expandtabs(1)) #TAB键用1个空格表示
>>> PatHoo hello

name='PatHoo'
print(name.lower())
>>> pathoo
name='PatHoo'
print(name.upper())
>>> PATHOO

name='PatHoo say'
print(name.capitalize()) #首字母大写
>>> PatHoo say
print(name.swapcase()) #大小写翻转
>>> pAThOO SAY
msg='PatHoo say hi'
print(msg.title()) #每个单词的首字母大写
>>> PatHoo Say Hi
name='PatHoo123'
print(name.isalnum()) #字符串由字母和数字组成
>>> True
name='PatHoo'
print(name.isalpha()) #字符串只由字母组成
>>> True

num1=b'4' #Bytes
num2=u'4' #unicode,python3中无需加u就是unicode
num3='四' #中文数字
num4='Ⅳ' #罗马数字

#bytes,unicode
print(num1.isdigit())
>>> True
print(num2.isdigit())
>>> True
print(num3.isdigit())
>>> False
print(num4.isdigit())
>>> False


#isdecimal:unicode
print(num2.isdecimal())
>>> True
print(num3.isdecimal())
>>> False
print(num4.isdecimal())
>>> False


#isnumberic:unicode,汉字，罗马
print(num2.isnumeric())
>>> True
print(num3.isnumeric())
>>> True
print(num4.isnumeric())
>>> True