SQL Image DataType - C# Display Output

Question

I have an image data type in my table. When I query using SQL Server Management Studio, I get the following in my results window, both grid and text.

0x255044462D312E320D0A0D0A332030206F[Truncated for Length]

I am attempting to replicate this in a little c# program.

However, when I use either SqlCommand or LINQ I get the output: JVBERi0xLjINCg0KMyAwIG9iag0KPDwNCi9FIDIxODgyDQovSCBbIDExNTAgMTUxIF0NCi9MIDIyM[TRUNCATED]

Any thoughts to what I need to do to get the 0x25... output to display? I have tried doing byte[] conversions and Encoding, but can't seem to find the right one.

If I am not clear, please let me know.

Edit: I am not trying to display the image, just the 0x25...

Thoughts?

"JVBERi0xLjINCg0...." looks like encoded. What do you get when you print the byte array? — Alfred Myers
– Alfred Myers, Commented Sep 1, 2009 at 22:38

LukeH · Accepted Answer · 2009-09-01 22:44:50Z

4

string forDisplay = "0x" + BitConverter.ToString(yourByteArray).Replace("-", "");

answered Sep 1, 2009 at 22:44

LukeH

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Comments

LukeH · Accepted Answer · 2009-09-02 00:31:34Z

1

AFAIK, .Net does not include any methods to print an arbitrary byte array as a single hex number. (Until .Net 4.0's System.Numerics.BigInteger)

However, you should be able to write

"0x" + BitConverter.ToString(bytes).Replace("-", "")

Note that this is incredibly inefficient; if you want to do this in real code, use a StringBuilder in a loop.
EDIT: Like this:

public static string ToHexString(this byte[] bytes) { var builder = new StringBuilder(bytes.Length * 2 + 2); builder.Append("0x"); for (int i = 0; i < bytes.Length; i++) builder.Append(bytes[i].ToString("X2")); return builder.ToString(); }

2^nd EDIT: Here's a new version which really is faster. (Yes, I know you don't need it; here it is anyway)

private static char ToHexDigit(int i) {
    if (i < 10) 
        return (char)(i + '0');
    return (char)(i - 10 + 'A');
}
public static string ToHexString(byte[] bytes) {
    var chars = new char[bytes.Length * 2 + 2];

    chars[0] = '0';
    chars[1] = 'x';

    for (int i = 0; i < bytes.Length; i++) {
        chars[2 * i + 2] = ToHexDigit(bytes[i] / 16);
        chars[2 * i + 3] = ToHexDigit(bytes[i] % 16);
    }

    return new string(chars);
}

edited Sep 2, 2009 at 0:31

LukeH

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answered Sep 1, 2009 at 22:44

SLaks

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5 Comments

CodeLikeBeaker Over a year ago

Thank you also for your response. this program will not go into production, so i don't have a worry for performance. I appreciate your responses!

LukeH Over a year ago

@SLaks: I just ran some quick tests, and the StringBuilder loop appears to be 2 or 3 times slower than the "incredibly inefficient" BitConverter/Replace.

SLaks Over a year ago

I cannot imagine why; I'll take a look.

SLaks Over a year ago

I reproduced the slowness. I suspect it's because of byte.ToString, which needs to parse its input & handle cultures, etc. Here's a version which really is faster.

LukeH Over a year ago

@SLaks: Yep, the new version is faster! This is pretty much what BitConverter.ToString does behind-the-scenes, but obviously you skip adding the hyphens which means that you don't then need the Replace call to remove them afterwards.

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