python安装

python3:
1.拿到源码包(3.6) —>去官网下载(www.python.org)
2.tar zxf Python-3.6.4.tgz -C /opt/ #解压安装包
3.进入解压目录编译和安装：
yum install gcc zlib zlib-devel openssl-devel -y #解决依赖性
4.cd /opt/ cd Python-3.6.4/ #进入解压的安装包进行编译
./configure --prefix=/usr/local/python3 --with-ssl
–prefix：安装路径 --with-ssl：添加ssl加密
make && make install：安装
5.测试：cd /usr/local/python3/bin ./python3
6.添加python3的命令到环境变量中
方法1：
临时添加：

export PATH="/usr/local/python3/bin:$PATH"
python3
Python 3.6.4 (default, Aug 26 2019, 21:44:00) 
[GCC 4.8.2 20140120 (Red Hat 4.8.2-16)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

永久添加:

echo export PATH="/usr/local/python3/bin:$PATH" >> ~/.bashrc
vim ~/.bashrc 
source ~/.bashrc 
python3
Python 3.6.4 (default, Aug 26 2019, 21:44:00) 
[GCC 4.8.2 20140120 (Red Hat 4.8.2-16)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> quit
Use quit() or Ctrl-D (i.e. EOF) to exit
>>> 

方法2：
做软连接
ln -s /usr/local/python3.6/bin/python3.6 /usr/local/bin/
##测试是否安装成功
python3
##安装ipython

cd /usr/local/python3.6/bin
pip3.6 install ipython

第一个py命令

#coding:utf-8
#python2.x:默认使用ASCII编码
#python3.x:默认使用UTF-8编码
#1.没有分号(编码规范 PEP8)
#2.严格按照缩进的语言

print('白茶清欢无别事')
print('越努力')

##注释
#单行注释
“”"
xxxxx 多行注释
xxxx
“”"

输入和输出

##python3.x
input():接收任意数据类型
python3.x中没有raw_input()

 >>> input('Num:')
 Num:2
 '2'
 >>> input('Num:')
 Num:abc
 'abc'
 >>> input('Passwd:')
 Passwd:123
 '123'
#输入内容不回显
 >>> import getpass
 >>> num = getpass.getpass('请输入密码：')
 请输入密码：
 >>> print(num)
 123

##python2.x
input():只支持正确的数值类型
raw_input():数值和字符串

>>> input('Num:')
 Num:2
 2
 >>> input('Num:')
 Num:1.2
 1.2
 >>> input('Num:')
 Num:redhat
 Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
   File "<string>", line 1, in <module>
 NameError: name 'redhat' is not defined
 >>> raw_input('Num:')
 Num:2
 '2'
 >>> raw_input('Num:')
 Num:1,2
 '1,2'
 >>> raw_input('Num:')
 Num:redhat
 'redhat'
 >>>

#如果接收到的数值要进行比较的时候，一定要转换为同一种类型

 >>> age = input('age:')
 age:19
 >>> age
 '19'
 >>> age > 18
 Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
 TypeError: '>' not supported between instances of 'str' and 'int'
 >>> age = int(age)
 >>> age
 19
 >>> age > 18
 True
 >>> age = int(input('age:'))
 age:18
 >>> age
 18

格式化输出

格式化输出
%s:代表字符串 %d:整型

 >>> name = 'westos'
  >>> name
  'westos'
  >>> age = 12
  >>> print('%s的年龄是%d' %(name,age))
  westos的年龄是12
  >>> age = 18
  >>> print('%s的年龄是%d' %(name,age))
  westos的年龄是18
  >>> age = '19'
  >>> print('%s的年龄是%d' %(name,age))
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
  TypeError: %d format: a number is required, not str
  >>> age = 19.5
  >>> print('%s的年龄是%d' %(name,age))
  westos的年龄是19

浮点型 %f

 >>> money=23121312.32314432
  >>> name = 'Tom'
  >>> print('%s的工资为%f' %(name,money))
  Tom的工资为23121312.323144
  >>> money=60000
  >>> print('%s的工资为%f' %(name,money))
  Tom的工资为60000.000000
  >>> money=60000.99
  >>> print('%s的工资为%f' %(name,money))
  Tom的工资为60000.990000
  >>> print('%s的工资为%.2f' %(name,money))
  Tom的工资为60000.99
  >>> money=60000
  >>> print('%s的工资为%.3f' %(name,money))
  Tom的工资为60000.000

整数的占位：不够的位数 前面补0

>>> sid = 1
  >>> name = 'lily'
  >>> print('%s的学号为000%d' %(name,sid))
  lily的学号为0001
  >>> sid = 2
  >>> print('%s的学号为000%d' %(name,sid))
  lily的学号为0002
  >>> sid = 10
  >>> print('%s的学号为000%d' %(name,sid))
  lily的学号为00010
  >>> print('%s的学号为%.5d' %(name,sid))
  lily的学号为00010
  >>> sid = 1
  >>> print('%s的学号为%.5d' %(name,sid))
  lily的学号为00001
  >>> sid = 20
  >>> sid = 100
  >>> print('%s的学号为%.5d' %(name,sid))
  lily的学号为00100

百分号的实现

>>> scale = 0.1
  >>> print('数据的比例是:%.2f' %(scale))
  数据的比例是:0.10
  >>> print('数据的比例是:%.2f' %(scale * 100))
  数据的比例是:10.00
  >>> print('数据的比例是:%.2f%' %(scale * 100))
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
  ValueError: incomplete format
  >>> print('数据的比例是:%.2f%%' %(scale * 100))
  数据的比例是:10.00%

变量

#驼峰命令法：
1.大驼峰：每一个单词的首字母都大写
FistName LastName
2.小驼峰：第一个单词小写开始后续单词首字母大写
fistName lastName
#str：表示一个字符串类型

   name = '房东的喵'
   print（name）

#int：表示一个整型

   age = 22
   print（age）

#float：表示一个浮点型

   height = 178.5
   print(height)

#bool:表示一个布尔型，只有True和False两个值

   gender = True
   print(gender)

#变量名只有在第一次出现的时候是定义变量

数据类型

整型

>>> a = 1
>>> print(a)
1

查看变量的类型

>>> type(a)
<class 'int'>

浮点型

>>> b = 1.2
>>> print(b)
1.2
>>> type(b)
<class 'float'>
>>> c = westos
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'westos' is not defined

字符串型

>>> c = 'westos'
>>> print(c)
westos
>>> c = "what's"
>>> print(c)
what's
>>> c = 'what's'
  File "<stdin>", line 1
    c = 'what's'
              ^
SyntaxError: invalid syntax
>>> c = 'what\'s'
>>> print(c)
what's

bool型(只有两个值：True False 非0即真)

>>> a = 1
>>> bool(a)
True
>>> bool(0)
False
>>> bool('')
False
>>> bool(' ')
True
>>> bool('redhat')
True

数据类型之间的转换

>>> a = 1
>>> type(a)
<class 'int'>
>>> float(a)
1.0
>>> type(a)
<class 'int'>
>>> b = float(a)
>>> b
1.0
>>> b = 2.0
>>> int(b)
2
>>> c = 'redhat'
>>> int(c)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: invalid literal for int() with base 10: 'redhat'
>>> b = 123
>>> str(b)
'123'
>>> c = '123'
>>> int(c)
123
>>> a
1
>>> b
123
>>> c
'123'

在内存中删除一个变量

>>> del a
>>> a
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'a' is not defined
>>> del b
>>> b
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'b' is not defined

算术运算符号

python2.x

>>> 5/2
2
>>> 100/300
0
>>> 5.0/2
2.5
>>> 100/300.0
0.3333333333333333

python2.x中除法需要将其中一个写为浮点型，不然回自己取整

python3.x

>>> 5/2
2.5
>>> 100/300
0.3333333333333333
>>> 

取余

>>> 5%2
1

取整

>>> 5//2
2

>>> a = 1
>>> a = a+1
>>> a
2
>>> a += 1
>>> a
3

逻辑运算符

“”"
and
1 and 2
两个条件同时满足 就返回True
只要有一个条件不满足，就返回False

or
1 or 2
两个条件只要满足一个 就返回True
两个条件都不满足，就返回False
“”"

python_score = 60
c_score = 50

if python_score >= 60 and c_score >=60:
    print('考试通过')
else:
    print('考试不通过')

标签：name,python,age,数据类型,py3.6,Num,print,input,python3
来源： https://blog.csdn.net/luxunlx123/article/details/100228104