C# 两个字符串比较并储存差异

string BeforeValue = "123456789";
string AfterValue  = "321465798";

// 参数验证
if (BeforeValue == null || AfterValue == null || BeforeValue.Length != AfterValue.Length)
{
    throw new ArgumentException("Invalid parameters.");
}

// 用 List 储存差异下标、两者比对的值
List<(int Index, char Before, char After)> differences = new List<(int Index, char Before, char After)>();
for (int i = 0; i < BeforeValue.Length; i++)
{
    if (BeforeValue[i] != AfterValue[i])
    {
        differences.Add((Index: i, Before: BeforeValue[i], After: AfterValue[i]));
    }
}

// 当有 BeforeValue ，AfterValue 有差异时可循环拿到对应下标和值
if (differences.Count > 0)
{
    // 这里使用了 ReadOnlyCollection 来创建只读集合。它接受一个普通的 List 作为参数，并将其封装成只读集合。
    ReadOnlyCollection<(int Index, char Before, char After)> readOnlyDifferences = new ReadOnlyCollection<(int Index, char Before, char After)>(differences);

    StringBuilder outputBuilder = new StringBuilder();
    foreach (var diff in readOnlyDifferences)
    {
        int diffIndex = diff.Index;
        char diffBefore = diff.Before;
        char diffAfter = diff.After;
        outputBuilder.AppendLine($"Index: {diffIndex}, Before: {diffBefore}, After: {diffAfter}");
    }

    Console.WriteLine(outputBuilder.ToString());
}

请注意，ReadOnlyCollection 是只读的，因此不能对其进行修改。这意味着无法通过 readOnlyDifferences.Add() 或 readOnlyDifferences.RemoveAt() 等方法来修改集合。它只是提供了一个只读的视图，以确保数据的不可变性。

运行结果：
Index: 0, Before: 1, After: 3
Index: 2, Before: 3, After: 1
Index: 4, Before: 5, After: 6
Index: 5, Before: 6, After: 5
Index: 7, Before: 8, After: 9
Index: 8, Before: 9, After: 8