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### Python入门教程知识点详解 #### 一、Python概述 **历史背景：** Python是由Guido van Rossum在1985年至1990年间创建的一种高级编程语言。它的设计哲学强调代码的可读性和简洁的语法，这使得Python成为初学者学习编程的理想选择。 **特点：** 1. **易学性：**Python拥有清晰简洁的语法结构，让初学者能够快速上手。 2. **可移植性：**Python可以在多种操作系统上运行，包括Windows、Linux、Mac OS等。 3. **面向对象：**Python支持面向对象编程(OOP)，可以定义类和对象，实现封装、继承和多态等特性。 4. **动态类型：**Python是一种动态类型语言，变量无需事先声明类型即可使用。 5. **解释型：**Python代码在执行时由解释器逐行解释执行，而非预先编译成机器码。 6. **丰富的库支持：**Python拥有庞大的标准库和第三方库，涵盖了Web开发、数据处理、科学计算等多个领域。 #### 二、Python环境搭建 **本地环境设置：** 1. **获取Python：**可以通过访问Python官网(https://www.python.org/)下载最新版本的Python安装包。 2. **安装Python：**按照下载的安装向导进行安装。安装过程中可以选择将Python添加到系统环境变量中，这样可以更方便地在命令行中使用Python。 3. **设置环境变量：** - **Unix/Linux环境下设置路径：**编辑`~/.bashrc`或`~/.bash_profile`文件，添加以下内容： ```bash export PATH=$PATH:/usr/local/bin/python3 ``` - **Windows环境下设置路径：**进入“控制面板” -> “系统与安全” -> “系统” -> “高级系统设置” -> “环境变量”，在系统变量中找到`Path`，将其编辑，添加Python安装路径。 4. **Python环境变量：**通过设置环境变量来指定Python解释器的位置以及其他相关配置。 5. **运行Python：**安装完成后，可以通过命令行输入`python`或`python3`(取决于系统的默认版本)来启动Python交互式环境。 #### 三、Python基本语法 **第一个Python程序：** 编写一个简单的Hello World程序是学习任何编程语言的起点。例如： ```python print("Hello, World!") ``` **标识符：** Python中的标识符是指用来命名变量、函数、类等的名称。命名规则如下： - 标识符只能包含字母、数字和下划线。必须以字母或下划线开头。 - 区分大小写，如`Variable`和`variable`是两个不同的标识符。 **关键字：** Python有一些保留的关键字，不能作为标识符使用。例如： - `if` - `else` - `for` - `while` - `def` - `class` **行和缩进：** Python使用缩进来表示代码块。一般情况下，使用4个空格作为一个缩进层次。 **多行语句：** Python支持在一行内书写多条语句，也支持跨多行书写一条语句。例如： ```python a = 1; b = 2 # 在同一行内书写两条语句 a = (1 + 2 + 3 + 4) # 跨多行书写一条语句 ``` **引号：** Python支持单引号(`'`)和双引号(`"`)，两者可以互换使用。例如： ```python message = "Hello, world!" message = 'Hello, world!' ``` **注释：** Python支持两种类型的注释：单行注释和多行注释。 - 单行注释以`#`开头。 - 多行注释使用三个单引号(`'''`)或三个双引号(`"""`)包围起来。 **等待用户输入：** Python提供了`input()`函数来接收用户的键盘输入。例如： ```python name = input("请输入您的名字：") print("您好，" + name) ``` **命令行参数：** 通过`sys.argv`列表可以访问传递给脚本的命令行参数。例如： ```python import sys print("脚本名:", sys.argv[0]) print("第一个参数:", sys.argv[1]) ``` 以上内容涵盖了Python入门的基础知识点，从Python的历史背景、特点、环境搭建到基本语法等方面进行了详细的介绍。通过这些知识点的学习，可以帮助初学者建立起对Python编程的基本认识，并为进一步深入学习打下坚实的基础。

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Table of Contents

About the Tutorial .......................................................................................................................................... i

Audience ........................................................................................................................................................ i

Prerequisites .................................................................................................................................................. i

Disclaimer & Copyright ................................................................................................................................... i

Table of Contents .......................................................................................................................................... ii

1. OVERVIEW ................................................................................................................................ 1

History of Python .......................................................................................................................................... 1

Python Features ............................................................................................................................................ 1

2. ENVIRONMENT ......................................................................................................................... 3

Local Environment Setup............................................................................................................................... 3

Getting Python .............................................................................................................................................. 3

Installing Python ............................................................................................................................................ 4

Setting up PATH ............................................................................................................................................ 5

Setting path at Unix/Linux ............................................................................................................................ 5

Setting path at Windows ............................................................................................................................... 5

Python Environment Variables ...................................................................................................................... 6

Running Python ............................................................................................................................................. 6

3. BASIC SYNTAX ........................................................................................................................... 9

First Python Program .................................................................................................................................... 9

Python Identifiers........................................................................................................................................ 10

Python Keywords ........................................................................................................................................ 11

Lines and Indentation .................................................................................................................................. 11

Multi-Line Statements ................................................................................................................................. 14

Quotation in Python .................................................................................................................................... 14

Python

iii

Comments in Python ................................................................................................................................... 14

Using Blank Lines ........................................................................................................................................ 15

Waiting for the User .................................................................................................................................... 15

Multiple Statements on a Single Line .......................................................................................................... 16

Multiple Statement Groups as Suites .......................................................................................................... 16

Command Line Arguments .......................................................................................................................... 16

Accessing Command-Line Arguments .......................................................................................................... 17

Parsing Command-Line Arguments ............................................................................................................. 18

getopt.getopt method ................................................................................................................................. 18

Exception getopt.GetoptError: .................................................................................................................... 18

4. VARIABLE TYPES ..................................................................................................................... 21

Assigning Values to Variables ...................................................................................................................... 21

Multiple Assignment ................................................................................................................................... 22

Standard Data Types ................................................................................................................................... 22

Python Numbers ......................................................................................................................................... 22

Python Strings ............................................................................................................................................. 24

Python Lists ................................................................................................................................................. 25

Python Tuples ............................................................................................................................................. 26

Python Dictionary ....................................................................................................................................... 27

Data Type Conversion ................................................................................................................................. 28

5. BASIC OPERATORS .................................................................................................................. 30

Types of Operators ...................................................................................................................................... 30

Python Arithmetic Operators ...................................................................................................................... 30

Python Comparison Operators .................................................................................................................... 32

Python Assignment Operators .................................................................................................................... 35

Python Bitwise Operators ........................................................................................................................... 38

Python

Python Logical Operators ............................................................................................................................ 40

Python Membership Operators ................................................................................................................... 40

Python Identity Operators........................................................................................................................... 42

Python Operators Precedence ..................................................................................................................... 44

6. DECISION MAKING.................................................................................................................. 47

If Statement ................................................................................................................................................ 48

If…else Statement ....................................................................................................................................... 49

The elif Statement ....................................................................................................................................... 51

Single Statement Suites ............................................................................................................................... 53

7. LOOPS .................................................................................................................................... 54

While Loop .................................................................................................................................................. 55

The Infinite Loop ......................................................................................................................................... 57

Using else Statement with Loops ................................................................................................................ 58

Single Statement Suites ............................................................................................................................... 59

For Loop ...................................................................................................................................................... 59

Iterating by Sequence Index ........................................................................................................................ 61

Using else Statement with Loops ................................................................................................................ 62

Nested Loops .............................................................................................................................................. 63

Loop Control Statements............................................................................................................................. 65

Break Statement ......................................................................................................................................... 66

Continue Statement .................................................................................................................................... 68

Pass Statement ........................................................................................................................................... 69

8. NUMBERS ............................................................................................................................... 71

Number Type Conversion ............................................................................................................................ 72

Random Number Functions ......................................................................................................................... 74

Trigonometric Functions ............................................................................................................................. 74