一 点睛

本篇介绍如何通过difflib模块实现文件内容差异对比。difflib作为 Python的标准库模块，无需安装，作用是对比文本之间的差异，且支持输出可读性比较强的HTML文档，与Linux下的diff命令相似。我们可以使用difflib对比代码、配置文件的差别，在版本控制方面是非常有用。 Python 2.3或更高版本默认自带difflib模块，无需额外安装。

二 两个字符串的差异对比

1 点睛

本例通过使用difflib模块实现两个字符串的差异对比，然后以版本控制风格进行输出。

2 代码
————————————————
 

#!/usr/bin/python
import difflib
 
text1 = """
text1:
This module provides classes and functions for comparing sequences.
including HTML and context and unified diffs.
difflib document v7.4
add string
"""
 
text1_lines = text1.splitlines()
 
text2 = """
text2:
This module provides classes and functions for Comparing sequences.
including HTML and context and unified diffs.
difflib document v7.5"""
 
text2_lines = text2.splitlines()
 
d = difflib.Differ()
diff = d.compare(text1_lines, text2_lines)
print ('\n'.join(list(diff)))

结果

E:\Python\python_auto_maintain\venv\Scripts\python.exe E:/Python/python_auto_maintain/2_1_1.py  
- text1:
?     ^
+ text2:
?     ^
- This module provides classes and functions for comparing sequences.
?                                                ^
+ This module provides classes and functions for Comparing sequences.
?                                                ^
  including HTML and context and unified diffs.
- difflib document v7.4
?                     ^
+ difflib document v7.5
?                     ^
- add string

说明

采用Differ（）类对两个字符串进行比较，另外difflib的 SequenceMatcher（）类支持任意类型序列的比较，HtmlDiff（）类支持将比较结果输出为HTML格式。