数据类型内置方法之数据类型与字符串类型

Posted 2021-11-28 williamkong94

数据类型内置方法

数字类型内置方法

整型

• 1.用途：年龄、身份证号码、手机号。。。
• 2.定义方式：

age1 = 18
age2 = int(18)
print(age1)
print(id(age1))
print(type(age1))
print(type(age2))

18
1723559936
<class 'int'>
<class 'int'>

• 3.常用操作和内置方法：+ - * / // ** % ；无内置方法
• 4.存一个值or多个值：一个值
• 5.有序or无序（有索引为有序，无索引为无序）：根本没有有序或无序的说法
• 6.可变or不可变：不可变

#不可变类型：值变则ID变
age = 18
print(id(age))
age += 1
print(id(age))

1723559936
1723559968

#可变类型：值变ID则不变
list1 = ['name','height','weight']
print(list1)
print(id(list1))
list1[1] = 185
print(list1)
print(id(list1))

['name', 'height', 'weight']
1701728445128
['name', 185, 'weight']
1701728445128

浮点型

• 1.用途：身高、体重、薪水、存款
• 2.定义方式：

salary1 = 1.5
salary2 = float(1.5)
print((salary1))
print(id(salary1))
print(type(salary1))
print(type(salary2))

1.5
1701727543560
<class 'float'>
<class 'float'>

• 3.常用操作和内置方法：+ - * / ** // % :无内置方法
• 4.存一个值or多个值： 一个值
• 5.有序or无序：根本没有有序无序一说
• 6.可变or不可变：不可变

字符串类型内置方法

• 1.用途：名字、单个爱好
• 2.定义方式：

name1 = 'william'
name2 = "william"
name3 = '''
william1
william2
'''
name4 = """
william3
william4
"""
print(type(name1))
print(type(name4))

<class 'str'>
<class 'str'>

• 3.常用操作和内置方法：
  1.优先掌握
  *1.按索引取值

my_info_list = ['name','height', 'weight','hobby',['reading','running']]
my_info = "name height weight hobby ['reading','running']"

print(my_info_list[2])
print(my_info[2])
print(my_info_list[4])
print(my_info[4])
print(my_info[5])

weight
m
['reading', 'running']
 
h

***2.切片（顾头不顾尾），步长的正负控制行进的方向，左行进还是右行进。

my_info = "name height weight hobby ['reading','running']"
print(my_info[:])
print(my_info[0:6])
print(my_info[0:8:2])
print(my_info[-1:-4:-1])
print(my_info[-4:-1])
print(my_info[-4:])

name height weight hobby ['reading','running']
name h
nm e
]'g
ng'
ng']

***3.长度len

my_info = "name height weight hobby ['reading','running']"
print(len(my_info))

46

***4.成员运算 in ? not in

my_info = "name height weight hobby ['reading','running']"
print('height' in my_info)
print('hobbies'in my_info)

True
False

***5.移除空白strip，默认为空格

test = '  a abc   a'
print(test.strip())
print(test.strip('a'))

a abc   a
  a abc   

***6.切分split

my_info = "name height weight hobby ['reading','running']"
print(my_info.split())
print(my_info.split(' ',2))
print(my_info.split('i'))

['name', 'height', 'weight', 'hobby', "['reading','running']"]
['name', 'height', "weight hobby ['reading','running']"]
['name he', 'ght we', "ght hobby ['read", "ng','runn", "ng']"]

***7.循环

my_info = "name height weight hobby ['reading','running']"
for i in my_info :
    print(i,end=' ')

n a m e   h e i g h t   w e i g h t   h o b b y   [ ' r e a d i n g ' , ' r u n n i n g ' ] 

2.需要掌握
*1.lstrip & rstrip

test = '   a  abc  a'
print(test.lstrip())
print(test.lstrip('a'))
print(test.rstrip('a'))

a  abc  a
   a  abc  a
   a  abc  

***2.lower & upper

my_info = "Name Height Weight hobby ['reading','running']"
print(my_info.lower())
print(my_info.upper())

name height weight hobby ['reading','running']
NAME HEIGHT WEIGHT HOBBY ['READING','RUNNING']

***3.startswith & endswith

my_info = "name height weight hobby ['reading','running']"
print(my_info.startswith('name'))
print(my_info.startswith('he'))
print(my_info.endswith('running'))

True
False
False

***4.rsplit

my_info = "name height weight hobby ['reading','running']"
print(my_info.rsplit(' '))
print(my_info.rsplit(' ',2))

['name', 'height', 'weight', 'hobby', "['reading','running']"]
['name height weight', 'hobby', "['reading','running']"]

***5.join

my_info = "name height weight hobby ['reading','running']"
my_info_split = my_info.split()
print(my_info)
print(my_info_split)
print(''.join(my_info_split))
print('.'.join(my_info_split))

name height weight hobby ['reading','running']
['name', 'height', 'weight', 'hobby', "['reading','running']"]
nameheightweighthobby['reading','running']
name.height.weight.hobby.['reading','running']

***6.replace

my_info = "name height weight hobby ['reading','running']"
print(my_info.replace('name','william').replace('weight','150'))

william height 150 hobby ['reading','running']

***7.isdigit

print('10dsf'.isdigit())
print('10'.isdigit())

False
True

**3.了解

# find \ rfind \ index \ rindex \ count
his_info = 'Name 1 WHEIGHT reading running reading 1 height'
print(his_info.find('1'))  
print(his_info.find('18'))  #记住不是False，而是-1
print(his_info.rfind('1'))
print(his_info.rfind('z'))  #记住不是False，而是-1

5
-1
39
-1

his_info = 'Name 1 WHEIGHT reading running reading 1 height'
print(his_info.index('WHEIGHT'))
#print(his_info.index('18'))  #会报错

7

his_info = 'Name 1 WHEIGHT reading running reading 1 height'
print(his_info.count('reading'))

2

# center \ ljust \ rjust \ zfill
print('SS'.center(20,'*'))
print('SS'.center(20,'+'))
print('SS'.ljust(20,'*'))
print('SS'.rjust(20,'+'))
print('SS'.zfill(20))

*********SS*********
+++++++++SS+++++++++
SS******************
++++++++++++++++++SS
000000000000000000SS

# expandtabs
print('\tTom'.expandtabs(4))

    Tom

#capitalize \ swapcase \ title
print('tom and jerry'.capitalize())
print('Tom and Jerry'.swapcase())
print('tom and jerry'.title())

Tom and jerry
tOM AND jERRY
Tom And Jerry

# is系列
print('tom'.isdigit())
print('tom'.isalpha())
print('10'.isalpha())

False
True
False

• 4.存一个值or多个值：一个值
• 5.有序or无序：有序
• 6.可变or不可变：不可变

name = 'William'
print(name)
print(id(name))
name += '2'
print(name)
print(id(name))

William
1701731277152
William2
1701731197360