c# - Find an array (byte[]) inside another array?

Question

What is the simplest way to find a byte[] inside another byte[]? i have a feeling i could do it with linq but i dont know how.

Note: I did a search with the [c#] and didnt find anything, i am surprised.

Answer 1

Here's a faster version of Ergwun's excellent answer:

static int SearchBytes( byte[] haystack, byte[] needle ) {
    var len = needle.Length;
    var limit = haystack.Length - len;
    for( var i = 0;  i <= limit;  i++ ) {
        var k = 0;
        for( ;  k < len;  k++ ) {
            if( needle[k] != haystack[i+k] ) break;
        }
        if( k == len ) return i;
    }
    return -1;
}

In a brief test with an 11MB haystack and 9 byte needle, this was about three times faster.

The optimizations are:

• No function call each time through the outer loop.
• Needle length and search limit are cached.
• Redundant length test at the beginning of match() is removed.

Of course for long byte arrays you'd want to use something like a Boyer-Moore search, but for many purposes a simple algorithm like this is good enough, and it has the virtue of being short and easy to understand and verify.