How do I initialize a fixed byte array?

Question

I have the following struct:

[StructLayout(LayoutKind.Sequential, Pack = 1)]
struct cAuthLogonChallenge
{
    byte cmd;
    byte error;
    fixed byte name[4];

    public cAuthLogonChallenge()
    {
        cmd = 0x04;
        error = 0x00;
        name = ???
    }
}

name is supposed to be a null-terminated ASCII string, and Visual Studio is rejecting all my ideas to interact with it. How do I set it?

digEmAll · Accepted Answer · 2010-05-31 07:16:15Z

1

You need to switch to unsafe mode to use fixed statement

http://msdn.microsoft.com/en-us/library/f58wzh21%28v=VS.80%29.aspx

http://msdn.microsoft.com/en-us/library/chfa2zb8%28v=VS.80%29.aspx

http://msdn.microsoft.com/en-us/library/zycewsya%28v=VS.80%29.aspx

Change your struct definition to unsafe struct ... then you can initialize your array like in c/c++

answered May 31, 2010 at 7:16

digEmAll

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Comments

György Andrasek · Accepted Answer · 2010-05-31 08:11:51Z

1

Got it:

[StructLayout(LayoutKind.Sequential, Pack = 1)]
unsafe struct cAuthLogonChallenge
{
    byte cmd;
    byte error;
    fixed byte name[4];

    public cAuthLogonChallenge(byte dummy)
    {
        cmd = 0x04;
        error = 0x00;
        fixed (byte* p = this.name)
        {
            *p = (byte)'J';
            *(p + 1) = (byte)'o';
            *(p + 2) = (byte)'n';
            *(p + 3) = 0;
        }
    }
}

answered May 31, 2010 at 8:11

György Andrasek

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1 Comment

unknown6656 Over a year ago

remember that *[a + b] is identical to a[b] in C#/C++/C ..., meaning that you can write the last 3 lines as p[1] = ...; p[2] = ...; p[3] = ...;

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