数据类型深入讲解

一：数字

int：

x=10  本质是 x=int(10)

x=int('111')

字符串转行成int类型，‘‘ ’’里面只能存一串数字（字符、浮点值都不行）

总结：

1.int是不可变类型

2.只能存一个值

3.没有有序和无序之分

可变类型：是指内存空间里id不变的前提下，变量值可以改变，就叫可变类型

不可变类型：是值内存空间里，变量值发生改变，id也跟着改变，就叫不可变类型

float：

salary=3.1 本质是salary=float(3.1)

salary='3.1' 或者 salary='3'

字符串转行成float类型，‘‘ ’’里面只能存一串数字或浮点

总结：

1.int是不可变类型

2.只能存一个值

3.没有有序和无序之分

 二：字符串

str：根据索引来去

x=str（1）

x=str（【1,2,3】）

str可以把任意类型转换成字符串类型

name=("Hello World")
print(name[0])  #取第一个值
print(name[-1]) #取最后一个值
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
H
d


切片：顾头不顾尾

name="Hello World"
# print(name[0])  
# print(name[-1])

print(name[0:6])
print(name[0:6:2])   (name[0:6:2]) 0-6代表：只5个字符  2：表示取值步数  默认是1

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
Hello 
Hlo

print(name[::-1]) 倒着迈步，输出反转（取值范围 *：* 默认不写是从头到尾）
与str索引去值相比，切片取值可以定义范围，可以取多个值
注意：正向取同时步数也要是正

长度：len 
输出字符串总的个数，如何：

name="Hello World"
print(len(name))

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
11

成员运算：in  与 no in 

name="Hello World"
print("H" in "Hello World" )
print("H" not in "Hello World" )
print("H"in  name )
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
True
False
True

Strip移除字符：

name='***yangzhizong**   '
print(name.strip('*'))
print(name.lstrip())

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
yangzhizong**   
***yangzhizong**   

定义取多个值：需定义在strip（‘值1值2’）

name='***yangzhizong**'
print(name.strip('*g'))

应用环境：
password=input("输入密码：").strip()
password=int(password)
if password == "123":
    print('成功')

split：切分 将字符串切成列表   
split(':',1) 理解：从左到右找：切掉第一个‘：，以被切得为左右分开，分成多个字符串

name='yangzhizong:18:male:180'
l=name.split(':')
print(l)
l=name.split('y')
print(l)
l=name.split(':',1)  #1个：切一次，分左右2部分,切成列表，左右2部分依然保持原列表元素
print(l)
l=name.split(':',2)  #2个：切一次，分左右2部分
print(l)
被切到：之后，被：切得部分以三个字符串分开组成一个列表
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
['yangzhizong', '18', 'male', '180']
['', 'angzhizong:18:male:180']
['yangzhizong', '18:male:180']
['yangzhizong', '18', 'male:180']

name='a:1:2:ds1dsd'
l=name.split('1')
print(l)
l=name.split('1',1)  #从左到右切除第一个1
print(l)
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
['a:', ':2:ds', 'dsd']
['a:', ':2:ds1dsd']

循环：for循环

isdigit:
可以判断byteshes和unicode类型，是做常用的用于判断字符是否为“数字”的方法

age=input('>>: ')
print(age.isdigit())

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
>>: aa
False
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
>>: 22
True

join：将list中单个字符串，用定义的字符链接成一个大的字符串

name=['egon','say','hello','world']
l='/'.join(name)
print(l)
print(type(l))  #输出格式是字符串
print(type(name)) #原格式是列表

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
egon/say/hello/world
<class 'str'>
<class 'list'>

name=['egon','say','hello','world']
print(''.join(name)) #默认是空格

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
egonsayhelloworld

replace: 取代 替换值  replace(原值,要替换为的值,要替换几个))

name='yangzhizong:18:male:180  yangzhizong love study'
print(name.replace('yangzhizong','mawenjie',1)) #要替换几个
print(name.replace('yangzhizong','mawenjie',2))

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
mawenjie:18:male:180  yangzhizong love study
mawenjie:18:male:180  mawenjie love study



三：列表
作用：多个装备、爱好..

按索引取值：

l=[1,2,3,4,5,6]
print(l[0:3:1])
print(l[2::-1])
print(l[::-1])

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
[1, 2, 3]
[3, 2, 1]
[6, 5, 4, 3, 2, 1]

切片：

username=['zhansan','lisi','wangwu','liming']
print(username[0:3])
print(username[0:3:2])

username[0]='ZHANGSAN' 也可以更改

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
['zhansan', 'lisi', 'wangwu']
['zhansan', 'wangwu']

['ZHANGSAN', 'lisi', 'wangwu', 'liming']

追加：

username=['zhansan','lisi','wangwu','liming']
username.append('qita')
print(username)
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
['zhansan', 'lisi', 'wangwu', 'liming', 'qita']


往制定位置添加：insert

username=['zhansan','lisi','wangwu','liming']
username.insert(0,'qita')
print(username)
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
['qita', 'zhansan', 'lisi', 'wangwu', 'liming']




删除1：del
安装索引删除

username=['zhansan','lisi','wangwu','liming']
del username[0]  
print(username)
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
['lisi', 'wangwu', 'liming']

删除2：remove
安装元素的值去删除
username=['zhansan','lisi','wangwu','liming']
username.remove('zhansan')
print(username)

username是单纯的删除，不会看到你删除的值，没有返回值

username=['zhansan','lisi','wangwu','liming']
shiji=username.remove('zhansan')
print(shiji)

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
None

删除3：pop
拿走一个值是按照索引去删除的，有返回值
如果pop不指定参数默认从最后一个删

username=['zhansan','lisi','wangwu','liming']
info=username.pop(0)
print(username)
print(info)

E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
['lisi', 'wangwu', 'liming']
zhansan

循环：

username=['zhansan','lisi','wangwu','liming']
for name in username:
    print(name)
E:PycharmProjectsuntitledvenvScriptspython.exe E:/PycharmProjects/untitled/day5/day5课堂笔记.py
zhansan
lisi
wangwu
liming