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Nin's questions

Martin Hope
Nin
Asked: 2024-09-22 13:50:37 +0800 CST
  • 8

我在 C#（.NET8 版本）中处理数字时发现了一些奇怪的行为8.0.400。

我创建了一个自定义类型来包装数字，这是展示行为的最小化代码：

struct Mystery<T>(T value)
    where T : IBinaryInteger<T>
{
    public T Value { get; } = value;

    public int GetByteCount() => Value.GetByteCount();
}

执行代码：

Mystery<BigInteger> mystery = new(short.MaxValue);

// Mystery<BigInteger> mystery = new(new BigInteger(short.MaxValue)); // same behavior

Console.WriteLine(mystery.GetByteCount()); // 4
Console.WriteLine(mystery.Value.GetByteCount()); // 2
Console.WriteLine(((IBinaryInteger<BigInteger>)mystery.Value).GetByteCount()); // 4

输出：

4
2
4

由于我创建了Mystery用于环绕数字的类型，因此我希望mystery.GetByteCount()其行为与 完全相同Value.GetByteCount()。但是，如输出所示，我的代码并未按预期工作。

我哪里做错了？我应该如何修改我的Mystery.GetByteCount()才能使其返回预期结果Value.GetByteCount()？

以下是 NUnit 测试，用于阐明预期行为：

[TestCase(0)] // expect 1, but was 4
[TestCase(byte.MaxValue)] // expect 2, but was 4
[TestCase(short.MaxValue)] // expect 2, but was 4
[TestCase(char.MaxValue)] // expect 3, but was 4
[TestCase(int.MaxValue)] // expect 4, PASSED
[TestCase(long.MaxValue)] // expect 8, PASSED
public void MysteryBigInt_GetByteCount(long value)
{
    Mystery<BigInteger> mystery = new(value);
    BigInteger bigInt = new(value);
    int expectedByteCount = bigInt.GetByteCount();
    Assert.Multiple(
        () =>
        {
            // PASSED
            Assert.That(mystery.Value.GetByteCount(), Is.EqualTo(expectedByteCount));

            // ony passed for int and long
            Assert.That(mystery.GetByteCount(), Is.EqualTo(expectedByteCount));
        });
}
c#