Introduction and foundation of automation-python

introduction of 1.1-python:

to put it simply, the python thing is a programming language called Guido van Rossum, a program ape who spent his time in 1989, determined to develop a script. Its previous name is an inheritance in the ABC language. It's called Python because this great programmer, Guido van Rossum, is a fan of the BBC TV series-Monty Python's Flying Circus (Monty Python's Flying Circus).

1.2 Why to learn Python: Learning Python first to understand what kind of language Python is, you have to learn from the classification of programming languages

C and Python, Java, C #, etc.

C Language: The code compiles the machine code, the machine code executes directly on the processor, each instruction controls the CPU to work

Other languages: Code compiles to get bytecode, virtual machines execute bytecode and convert to machine code and then execute on processor

The language of Python and C Python was developed by C.

For use with: Python's class library is complete and concise, if you want to implement the same functionality, Python 10 lines of code can be solved, C may require 100 lines or more.
For speed: Python runs faster than C, forcing it to slow down.

Python and Java, C #, etc.

For use with: Linux original Python, no other languages; The above languages have a very rich class library support
For speed: Python may be slightly slower in speed

So, there is no essential difference between Python and other languages, other differences are: good at a field, rich in talent, preconceived.

Types of 1.3-python

• Cpython
  The official version of Python, implemented using the C language, is the most widely used, and the CPython implementation converts the source file (py file) into a bytecode file (PYc file) and then runs on the Python virtual machine.
• Jyhton
  Python Java implementation, Jython will dynamically compile Python code into Java bytecode, and then run on the JVM.
• IronPython
  In Python's C # implementation, IronPython compiles Python code into C # bytecode and then runs on the CLR. (similar to Jython)
• PyPy (Special)
  Python implements Python, which compiles Python bytecode bytecode into machine code.
• Rubypython, Brython ...

In addition to PyPy, the corresponding relationship and execution flow of Python are as follows:

PyPy, the Python bytecode is further processed on the basis of Python, which improves execution speed!

2.1Python Environment

Install Python

Windows:

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1、下载安装包    https://www.python.org/downloads/2、安装    默认安装路径：C:\python273、配置环境变量    【右键计算机】--》【属性】--》【高级系统设置】--》【高级】--》【环境变量】--》【在第二个内容框中找到 变量名为Path 的一行，双击】 --> 【Python安装目录追加到变值值中，用 ； 分割】    如：原来的值;C:\python27，切记前面有分号

Linux:

123	无需安装，原装Python环境 ps：如果自带2.6，请更新至2.7

Update python

Windows:

1

卸载重装即可

Linux:

Linux Yum relies on its own python, to prevent errors, the update here is actually to install a python

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查看默认Python版本python -V 1、安装gcc，用于编译Python源码    yum install gcc2、下载源码包，https://www.python.org/ftp/python/3、解压并进入源码文件4、编译安装    ./configure    make all    make install5、查看版本    /usr/local/bin/python2.7-V6、修改默认Python版本    mv /usr/bin/python /usr/bin/python2.6    ln -s /usr/local/bin/python2.7/usr/bin/python7、防止yum执行异常，修改yum使用的Python版本    vi /usr/bin/yum    将头部 #!/usr/bin/python 修改为 #!/usr/bin/python2.6

3.1-python Getting Started

	First program "Hello world!"
	#!/usr/bin/env python #声明python的环境变量, here the difference between Env and no env is: Add env will be based on the environment variables configured by the system to use the default Python environment to explain the program, without Env is directly through/usr /bin/python to execute #-*-coding:utf-8-*- #声明字符编码print ("Hello World") #在屏幕上打印 ' Hello World '

3.2 python Chinese encoding

Before learning Python's Chinese encoding, we need to know what the code is:

• Coding is the use of predetermined methods to digitally encode text, numbers, or other objects, or to convert information into a prescribed electrical pulse signal. Coding is the process of converting information from one form or format to another.
• However we need to understand the character encoding as follows:
  • ASCII code: United States Standard Information Interchange code, mainly used to display English and European languages; it can only be represented by a maximum of 8 bits (one byte), that is: 2**8 = 256, so the ASCII code can represent up to 256 symbols.
  • Unicode code: Also known as the Universal Code, the purpose is to solve the limitations of the traditional character encoding scheme, which sets a uniform and unique binary encoding for each character in each language, which specifies that although some characters and symbols are represented by at least 16 bits (2 bytes), that is: 2 **16 = 65536.
  • Utf-8: Is the compression and optimization of Unicode encoding, he no longer uses a minimum of 2 bytes, but all the characters and symbols are categorized: the contents of the ASCII code is saved with 1 bytes, the European characters are saved with 2 bytes, the Chinese character is saved in 3 bytes.

There is a difference between the Chinese encoding between python2.x and 3.x: it is necessary to declare or specify character encoding in the python2.x series environment, however python3.x does not need to declare character encoding.

• The Chinese code is as follows:
  • GB2312: GB code, was born in 1980, contains more than 7,000 Chinese characters
  • gbk:1995 year, a total of more than 20,000 Chinese characters included
  • GB18030: Is the 2000 to replace GBK1.0 and the birth of the official national standards, but also included the language of minority languages

Introduction and foundation of automation-python