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This article to share with you is about Python language how to get started quickly, Xiaobian feel quite practical, so share to everyone to learn, I hope you can read this article after some harvest, not much to say, follow Xiaobian to see it.

[Introduction]

Python is a dynamically interpreted programming language. Python can be used on Windows, UNIX, MAC and many other operating systems, as well as Java and. NET development platforms.

python logo

[Features]

Python is developed in C, but Python no longer has complex data types such as pointers in C.

Python has strong object-oriented features and simplifies object-oriented implementations. It eliminates object-oriented elements such as protected types, abstract classes, interfaces, etc.

3 Python code blocks are separated by spaces or tabs indented.

Python has only 31 reserved words and no semicolons, begin, end, etc.

Python is a strongly typed language, variables will correspond to a data type after creation, and different types of variables appearing in unified expressions need to be type converted.

[Creating a Development Environment]

1 You can download the installation package from www.python.org and install it via configure, make, make install.

2 You can also download the ActivePython package at www.activestate.com. (ActivePython is a binary wrapper around Python's core and common modules, a Python development environment published by ActiveState.) ActivePython makes Python easy to install and can be applied to a variety of operating systems. ActivePython includes some common Python extensions, as well as programming interfaces for Windows environments.) For ActivePython, if you are a Windows user, download the msi package and install it; if you are a Unix user, download the tar.gz package and extract it directly.

Python IDE, including PythonWin, Eclipse+PyDev plugin, Komodo, EditPlus

[Version]

Python2 and Python 3 are the two main versions.

Python2 is recommended for the following two situations:

1. When you have no full control over the environment in which you are about to deploy;

2 When you need to use certain third-party packages or extensions;

Python 3 is officially recommended and is a fully supported version in the future, and many feature improvements are currently only available on Python 3.

【hello world】

1 Create hello.py

2 Writing procedures:

if __name__ == '__main__': print "hello word"

3 Run the program:

python ./ hello.py

[Note]

1 Comment with a #followed by a space, whether it is a line comment or paragraph comment.

2 If you need to use Chinese comments in your code, you must add the following comments at the beginning of your python file:

# -* - coding: UTF-8 -* -

3 The following comments are used to specify the interpreter

#! /usr/bin/python

[File Type]

Python file types are divided into three types: source code, byte code, and optimized code. All of these can be run directly without compilation or concatenation.

2 Source code with.py extension, Python is responsible for interpretation;

3 The source file is compiled to produce a file with the extension.pyc, a compiled byte file. This file cannot be modified using a text editor. Pyc files are platform-independent and run on most operating systems. The following statements can be used to generate pyc files:

import py_compile py_compile.compile(‘hello.py’)

4 Optimized source files are suffixed with.pyo, i.e. optimized code. It also cannot be modified directly with a text editor, and the following commands can be used to generate pyo files:

python -O -m py_complie hello.py

[Variable]

1 Variables in python do not need to be declared, and variable assignment operations are the process of variable declaration and definition.

A new assignment in Python creates a new variable. Even if the names of variables are the same, the identities of variables are different. The id() function can be used to obtain variable identifiers:

x = 1 print id(x) x = 2 print id(x)

If a variable is not assigned, Python assumes that the variable does not exist.

4 Variables defined outside a function can be called global variables. Global variables can be accessed by any function inside the file and by external files.

5 Global variables are recommended to be defined at the beginning of the file.

You can also put global variables in a special file and reference them via import:

The gl.py file reads:

_a = 1 _b = 2

Reference global variables in use_global.py:

import gl def fun(): print gl._ a print gl._ b fun()

[Constant]

Python does not provide reserved words that define constants. You can define a constant class to implement the function of a constant.

class _const: class ConstError(TypeError): pass def __setattr__(self,name,vlaue): if self.__ dict__.has_key(name): raise self.ConstError, "Can’t rebind const(%s)"%name self.__ dict__[name]=value import sys sys.modules[__name__]=_const()

[Data Type]

Python numeric types are divided into integer, long integer, floating point, Boolean, and complex types.

Python has no character type.

Python has no common types, any type is an object.

4 If you need to see the type of a variable, you can use the type class, which returns the type of the variable or creates a new type.

Python has three ways to represent string types: single quotes, double quotes, and triple quotes. Single quotes and double quotes work the same. Python programmers prefer single quotes, C/Java programmers prefer double quotes for strings. Single quotes, double quotes or newlines can be entered in the triple quotes.

[Operators and Expressions]

Python does not support the increment and decrement operators. For example i++/i-is wrong, but i+=1 is OK.

2 1/2 equals 0.5 before Python 2.5 and 0 after Python 2.5.

3 is not equal to!= or

4 equals ==

In logical expressions, and means logical AND, or means logical OR, not means logical NOT.

[Control statement]

1 Conditional statement:

if (expression) : statement 1 else : statement 2

2 Conditional statements:

if (expression) : statement 1 elif (expression) : statement 2 … elif (expression) : statement n else : statement m

3 Conditional nesting:

if (expression 1) : if (expression 2) : statement 1 elif (expression 3) : statement 2 … else: statement 3 elif (expression n) : … else : …

Python itself has no switch statement.

5 Loop statements:

while(expression) : … else : …

6 Loop statements:

for variables in collection: … else : …

7 Python does not support for(i=0;i) like c

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