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Python is an interpreted language
Choice of python 2 or 3:
Python 2.7 is the latest and last version of 2, and the update supports Updates will stop in 2020, but companies that are currently using or have developed it continue to use python2, so the transition period for updates still has a way to go, and python 3 will be the long-term development in the future. A better choice (this is only for beginners), of course, when learning python3, you must understand the different features between 2 and 3.
Installation and configurationwindows
##linux, Mac
No installation required, original Python environment
ps: If you have , please update to 2.7 or other versions1 print 'Hello World!' #python2的写法2 print ('Hello World!') #python3的写法
name='Tom'
Variable names can only be any combination of letters, numbers or underscores
The first character of the variable name cannot be a number
The following keywords cannot be declared as variable names
['and', 'as', 'assert', ' break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'exec', 'finally', 'for', 'from', 'global' , 'if', 'import', 'in', 'is', 'lambda', 'not', 'or', 'pass', 'print', 'raise', 'return', 'try', ' while', 'with', 'yield']name= =name (name2)
should be displayed at the beginning of the file to tell the python interpreter what encoding to use to execute the source code, that is:
#!/usr/bin/env python# -*- coding: utf-8 -*- #告诉python字符编码 print "你好，世界"
注释
当行注视：# 被注释内容
多行注释：""" 被注释内容 """
数据类型初识
2 是一个整数的例子。
长整数 不过是大一些的整数。
3.23和52.3E-4是浮点数的例子。E标记表示10的幂。在这里，52.3E-4表示52.3 * 10-4。
(-5+4j)和(2.3-4.6j)是复数的例子，其中-5,4为实数，j为虚数，数学中表示复数是什么？。
int（整型）
"hello world"
接收用户输入
#!/usr/bin/env python#_*_coding:utf-8_*_
#name = raw_input("请输入用户名") #只有 python 2.x有这种写法name=input('请输入用户名：')print('Hello '+name)
if else ...
#!/usr/bin/env python# -*- coding: encoding -*-age=int(input('请输入年龄：')) #接收一个age值，这里因为age是一个int类型，所以需要强制转换一下if age<100: print('你还小') #判断age的值小于100的时候输出“你还小”else:print('你已经老了') #否则输出“你已经老了”if elif else ...
#!/usr/bin/env python# -*- coding: encoding -*-my_age=22 #定义一个自己的年龄age=int(input('请输入年龄')) #接收一个年龄if age==my_age:print('猜对了') #如果输入的值等于my_age的值 输出猜对了elif age<my_ageprint('猜小了') #输入的值小于my_age的值，输出才小了else:print('猜大了') #负责显示猜大了
while 循环 ...
#!/usr/bin/env python# -*- coding: encoding -*-count=0 #定义一个值为count的计数器while True: print(count) #如果为真就一直循环 这是一个死循环，不停止程序会一直执行count+=1 #循环一次给计数器+1
for 循环 ...
#!/usr/bin/env python# -*- coding: encoding -*-for i in range(10)print(i) #最简单的循环打印10次
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