C＃字节数组-有符号和无符号难题 [英] C# byte arrays - signed and unsigned dilemma

问题描述

我从一个有符号字节数组开始，然后转换为无符号..那么打印结果是否正确？

I start with a signed byte array and convert to unsigned.. so is the printed result correct?

byte[] unsigned = new byte[] {10,100,120,180,200,220,240};
sbyte[] signed = Utils.toSignedByteArray(unsigned);

打印（我只是在它们后面加上StringBuilder）：

And the print (I just append them with a StringBuilder):

签名：[10,100,120，-76，-56，-36，-16]

未签名：[10,100,120,180,200,220,240]

signed: [10,100,120,-76,-56,-36,-16]
unsigned : [10,100,120,180,200,220,240]

其中：

public static sbyte[] toSignedByteArray(byte[] unsigned){
    sbyte[] signed = new sbyte[unsigned.Length];
    Buffer.BlockCopy(unsigned, 0, signed, 0, unsigned.Length);
    return signed;
}

如果我更改为该参数，则会得到相同的结果。

If I change to this I get the same result.

sbyte[] signed = (sbyte[])(Array)unsigned;

不应使-128（带符号）变为0，-118变为10，依此类推。而不是10（有符号）= 10（无符号）！？

Shouldn't -128 (signed) become 0, -118 become 10, and so on.. and not 10 (signed) = 10 (unsigned)!?

因为

sbyte -128到127

字节0到255

Because
sbyte -128 to 127
byte 0 to 255

所以??

推荐答案

带符号的整数在二进制补码系统中表示。

Signed integers are represented in the Two's complement system.

示例：

Bits        Unsigned     2's complement
            value        value

00000000    0            0
00000001    1            1
00000010    2            2
01111110    126          126
01111111    127          127
10000000    128          −128
10000001    129          −127
10000010    130          −126
11111110    254          −2
11111111    255          −1

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