CODEWITHSUNDEEP
c#.netsqlsql-server-2008type-conversion
Dan7el
Dan7el

Reputation: 2047

C# .NET BitConverter doesn't work for SQL Server stored VarBinary read

We're storing an integer in our SQL Server 2008 database as a VARBINARY. Using Entity Framework, when reading this VARBINARY value, it returns, to the C# code, a byte array.

Yes. I know it doesn't necessarily make sense to store the integer as a VARBINARY in the database right off. There is a good reason for this storage method.

Hence, the integer value of 10762007 would actually be 0xA43717 if you examined the table with a SELECT statement. The actual value we get in our code after reading it into a byte array is:

byte[] b = new byte[]{0, 164, 55, 23};

Now, the uninitiated might think that a simple conversion back to an integer would be:

int myInt = BitConverter.ToInt32(b);

...which does not produce the desired results.

I figured this problem out by doing the following:

string bitString = string.Empty;
string[] bitArray = new string[4];

for ( int i = 0; i < 4; i++)
{
   bitArray[i] = Convert.ToString((int)b[i],2).PadLeft(8,"0");
   bitString += bitArray[i];
}

int theRealInt = Convert.ToInt32(bitString,2);

Which is essentially taking my integer representation of the hex values, converting them to a bit string, appending them appropriately, and then converting the big, giant bit string back to an integer.

This works but it seems like I'm doing more work than I need to. Is there some easier way to perform this action? Basically, we're storing an integer as a VARBINARY in the database, and then wanting to convert this back to the same integer in C# code.

Upvotes: 0

Views: 1053

Answers (2)

spender
spender

Reputation: 120508

Jon Skeet has a drop-in replacement for BitConverter (MiscUtil.Conversion.EndianBitConverter) that deals with endian issues, and it can be found in the Miscellaneous Utility Library

Upvotes: 0

I4V
I4V

Reputation: 35363

Just try

var myInt = BitConverter.ToInt32(b.Reverse().ToArray(),0);

or

var myInt = IPAddress.NetworkToHostOrder(BitConverter.ToInt32(b,0));

It is about Endianness

Upvotes: 2

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