C#中三字节表示的有符号整数转四字节有符号整数_c#多字节转有符号

方法1

private int Int24ToInt32_1(byte b1, byte b2, byte b3)
{
    uint uintTemp = (uint)(b1 * 0x1000000 + b2 * 0x10000 + b3 * 0x100);
    int intTemp = (int)uintTemp;
    return intTemp / 256;
}
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方法2

private int Int24ToInt32_2(byte b1, byte b2, byte b3)
{
    uint uintTemp = (uint)(b1 * 0x10000 + b2 * 0x100 + b3);
    if (b1 > 0x7f)
    {
        uintTemp += 0xff000000;
    }
    return (int)uintTemp;
}
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方法3

private int Int24ToInt32_3(byte b1, byte b2, byte b3)
{
    byte[] b = { 0, b3, b2, b1 };
    return BitConverter.ToInt32(b, 0) / 0x100;
}
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方法4

private int Int24ToInt32_4(byte b1, byte b2, byte b3)
{
    byte[] b = { b3, b2, b1, 0 };
    uint uintTemp = BitConverter.ToUInt32(b, 0);
    if (b1 > 0x7f)
    {
        uintTemp += 0xff000000;
    }
    return (int)uintTemp;
}
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