如何使用C#检测句子间的单词与字母差异？

要实现句子间的单词/字符层面差异检测，可以分两步处理：先做单词级对比，再对有差异的单词做字符级对比。以下是具体实现方案：

基础实现（按位置逐词对比） #

这种方式适合句子结构基本一致，仅部分单词/字符有修改的场景。

1. 单词级差异检测方法 #

将句子拆分为单词列表，按位置逐词对比，记录不同的单词对：

using System;
using System.Collections.Generic;
using System.Linq;

public static class DifferenceDetector
{
    public static List<Tuple<string, string>> GetWordDifferences(string sentence1, string sentence2)
    {
        var words1 = sentence1.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);
        var words2 = sentence2.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);
        var differences = new List<Tuple<string, string>>();
        
        int maxLength = Math.Max(words1.Length, words2.Length);
        for (int i = 0; i < maxLength; i++)
        {
            string word1 = i < words1.Length ? words1[i] : string.Empty;
            string word2 = i < words2.Length ? words2[i] : string.Empty;
            
            if (word1 != word2)
            {
                differences.Add(Tuple.Create(word1, word2));
            }
        }
        return differences;
    }
}

2. 字符级差异检测方法 #

针对有差异的单词，逐字符对比记录不同的字符对：

public static List<Tuple<char, char>> GetCharacterDifferences(string word1, string word2)
{
    var differences = new List<Tuple<char, char>>();
    int maxLength = Math.Max(word1.Length, word2.Length);
    
    for (int i = 0; i < maxLength; i++)
    {
        char c1 = i < word1.Length ? word1[i] : '\0';
        char c2 = i < word2.Length ? word2[i] : '\0';
        
        if (c1 != c2)
        {
            differences.Add(Tuple.Create(c1, c2));
        }
    }
    return differences;
}

3. 组合调用示例 #

将两个方法结合，输出完整的差异信息：

public static void DetectAndPrintDifferences(string sentence1, string sentence2)
{
    var wordDiffs = GetWordDifferences(sentence1, sentence2);
    Console.WriteLine("单词层面差异：");
    foreach (var diff in wordDiffs)
    {
        Console.WriteLine($"\"{diff.Item1}\" vs \"{diff.Item2}\"");
        
        if (!string.IsNullOrEmpty(diff.Item1) && !string.IsNullOrEmpty(diff.Item2))
        {
            var charDiffs = GetCharacterDifferences(diff.Item1, diff.Item2);
            Console.WriteLine("  字符层面差异：");
            foreach (var charDiff in charDiffs)
            {
                Console.WriteLine($"    '{charDiff.Item1}' vs '{charDiff.Item2}'");
            }
        }
    }
}

// 测试示例
DetectAndPrintDifferences("this is my book", "this is may book");
DetectAndPrintDifferences("how are this cook", "hope and this cook");

测试第一组句子会输出：

单词层面差异：
"my" vs "may"
  字符层面差异：
    'y' vs 'a'
    '\0' vs 'y'

测试第二组句子会输出：

单词层面差异：
"how" vs "hope"
  字符层面差异：
    'w' vs 'p'
    '\0' vs 'e'
"are" vs "and"
  字符层面差异：
    'r' vs 'n'

进阶实现（基于LCS处理单词顺序变化） #

如果句子存在单词顺序调换、新增/删除单词的情况，可以用**最长公共子序列（LCS）**算法来更准确识别差异类型（新增、删除、修改）：

public static List<(string OldWord, string NewWord, string ChangeType)> GetWordDifferencesWithLCS(string sentence1, string sentence2)
{
    var words1 = sentence1.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);
    var words2 = sentence2.Split(new[] {' '}, StringSplitOptions.RemoveEmptyEntries);
    
    int[,] lcsTable = new int[words1.Length + 1, words2.Length + 1];
    
    // 构建LCS表
    for (int i = 1; i <= words1.Length; i++)
    {
        for (int j = 1; j <= words2.Length; j++)
        {
            if (words1[i-1] == words2[j-1])
            {
                lcsTable[i,j] = lcsTable[i-1,j-1] + 1;
            }
            else
            {
                lcsTable[i,j] = Math.Max(lcsTable[i-1,j], lcsTable[i,j-1]);
            }
        }
    }
    
    var differences = new List<(string, string, string)>();
    int iIndex = words1.Length;
    int jIndex = words2.Length;
    
    // 回溯LCS表，识别差异类型
    while (iIndex > 0 || jIndex > 0)
    {
        if (iIndex > 0 && jIndex > 0 && words1[iIndex-1] == words2[jIndex-1])
        {
            iIndex--;
            jIndex--;
        }
        else if (jIndex > 0 && (iIndex == 0 || lcsTable[iIndex,jIndex-1] >= lcsTable[iIndex-1,jIndex]))
        {
            differences.Add((string.Empty, words2[jIndex-1], "新增"));
            jIndex--;
        }
        else if (iIndex > 0 && (jIndex == 0 || lcsTable[iIndex-1,jIndex] > lcsTable[iIndex,jIndex-1]))
        {
            differences.Add((words1[iIndex-1], string.Empty, "删除"));
            iIndex--;
        }
        else
        {
            differences.Add((words1[iIndex-1], words2[jIndex-1], "修改"));
            iIndex--;
            jIndex--;
        }
    }
    
    differences.Reverse();
    return differences;
}

内容的提问来源于stack exchange，提问作者barteloma