Getting Started-python-1

Python download

Python's latest source code, binary documents, news, etc. can be found on the Python website:

Python official website:http://www.python.org/

You can download Python documents in the following links, and you can download documents in HTML, PDF and PostScript formats.

Python document:www.python.org/doc/

Python installation

Python has been ported on many platforms (modified to make it work on different platforms).

You will need to download the binary code that is appropriate for your use of the platform, and then install Python.

If the binary code of your platform is not available, you need to compile the source code manually using the C compiler.

The compiled source code, with more selectivity in functionality, provides more flexibility for Python installation.

Here's how to install Python on different platforms:

Unix & Linux Platform Installation Python: (default 2.xx installed)

Here are the simple steps to install Python on UNIX & Linux platforms:

• Open a Web browser to access http://www.python.org/download/
• Select the source compression package for unix/linux.
• Download and unzip the zip package.
• If you need to customize some options to modify modules/setup
• execute the./configure Script
• Make
• Make install

After doing this, Python is installed in the/usr/local/bin directory, and the Python library is installed in/USR/LOCAL/LIB/PYTHONXX,XX for the version number of the python you are using.

Windows platform installs Python:

Here are the simple steps to install Python on the Window platform:

• Open a Web browser to access http://www.python.org/download/
• Select the Window platform installation package in the download list, in the package format:python-xyz.msi file, XYZ is the version number you want to install.
• To use setup python-xyz.msi, Windows systems must be supported with Microsoft Installer 2.0. Just save the installation file to your local computer, and then run it to see if your machine supports MSI. Windows XP and later versions already have MSI, and many older machines can also install MSI.
• After downloading, double-click the download package, go to the Python Installation Wizard, the installation is very simple, you just need to use the default settings always click "Next" until the installation is complete.

MAC Platform Installation Python:

The most recent Macs system comes with a python environment, and you can also download the latest version of the installation on the link http://www.python.org/download/ .

Environment variable Configuration

Programs and executables can be in many directories, and these paths are probably not in the search path where the operating system provides executable files.

The path is stored in an environment variable, which is a named string maintained by the operating system. These variables contain information about the available command-line interpreters and other programs.

Path variable in UNIX or Windows is path (Unix case-sensitive, Windows is case-insensitive).

In Mac OS, the setup process changes the Python installation path. If you need to reference Python in another directory, you must add a Python directory to the path.

Setting environment variables in Unix/linux

• in CSH Shell: input
• setenv PATH "$PATH:/usr/local/bin/python"
  , press "Enter".
• in Bash Shell (Linux): input
• Export PATH="$PATH:/usr/local/bin/python"
  , press "Enter".
• in sh or ksh shell: input
• PATH="$PATH:/usr/local/bin/python"
  , press "Enter".

Note:/usr/local/bin/python is the installation directory for Python.

Setting environment variables in Windows

To add a Python directory to an environment variable:

In the Command Prompt box (cmd): Enter

Path=%path%; C:\python

Press "Enter".

Note: C:\Python is the installation directory for Python.

You can also set it in the following ways:

• Right-click on "Computer" and click "Properties"
• Then click "Advanced System Settings"
• Select "Path" under the "System Variables" window and double click!
• Then in the "path" line, add the Python installation path (my D:\Python32), so later, add the path. PS: Remember, the path is separated directly by a semicolon ";"
• After the final setting is successful, on the cmd command line, enter the command "Python" and you can have the relevant display.

Python Environment variables

Here are a few important environment variables that apply to Python:

Variable name	Describe
PYTHONPATH	Pythonpath is the Python search path, and by default our import module will be searched from the Pythonpath.
Pythonstartup	After Python starts, look for the PYTHONSTARTUP environment variable and execute the execution code specified by the variable in this file.
Pythoncaseok	Adding Pythoncaseok environment variables makes python case-insensitive when importing modules.
Pythonhome	Another module search path. It is typically embedded in the Pythonstartup or Pythonpath directory, making it easier to switch between two module libraries.

Run Python

There are three ways to run Python:

1. Interactive interpreter:

You can enter Python from a command-line window and start writing Python code in the interactive interpreter.

You can do python coding in unix,dos or any other system that provides a command line or shell.

$ python # Unix/linux

Or

C:>python # Windows/dos

The following are the Python command-line parameters:

Options	Describe
-D	Display debug information at parse time
-O	Generate optimization code (. pyo file)
-S	Do not introduce a location to find Python paths at startup
-V	Output Python version number
-X	The built-in exception (for strings only) since the 1.6 release is obsolete.
-C cmd	Executes the Python script and runs the result as a CMD string.
File	Executes a Python script in the given Python file.

2. Command line script

In your application, you can execute a python script on the command line by introducing an interpreter, as follows:

$ python script.py # Unix/linux

Or

C:>python script.py # Windows/dos

Note: When executing a script, check to see if the script has executable permissions.

3. Integrated development Environment (ide:integrated development environment)

You can use a graphical user interface (GUI) environment to write and run Python code. The following are recommended for use by the IDE on each platform:

• Unix: IDLE is the earliest Python IDE on UNIX.
• Windows: Pythonwin is a Python integrated development environment that is superior to the IDE in many ways
• Macintosh: Python's Mac can use the idle IDE, and you can download the corresponding Mac's idle on your website.

Python Chinese encoding

If no encoding is specified in the Python file, an error occurs during execution:

#!/usr/bin/python

Print "Hello, World";

The above program execution output results are:

File "test.py", line 2

SyntaxError: Non-ASCII character ' \xe4 ' in file test. PY on line 2, but no encoding declared; see http://www.python.org/peps/ pep-0263.html for details

The default encoding format in Python is the ASCII format, which fails to print correctly when the encoding format is not modified, so the error occurs when reading Chinese.

The workaround is to add #-*-Coding:utf-8-*-or #coding =utf-8 at the beginning of the file.

Instance (Python 2.0+)

#!/usr/bin/python

#-*-Coding:utf-8-*-

Print "Hello, world";

the output is: Hello, World

So if you re-learn the process, the code contains Chinese, you need to specify the coding in the head.

Note: The python3.x source file uses Utf-8 encoding by default, so the Chinese can be parsed normally without specifying UTF-8 encoding.

Note: If you use the editor, you also need to set the encoding for the editor, such as the Pycharm setup step:

• Go to file > Settingsand search for encodingin the input box.
• Locate Editor > File encodings, and set the IDE Encoding and Project Encoding to Utf-8.

Getting Started-python-1