Agfdhyk

How can i search for a specified byte array and replace everything from the beginning to this byte array (included)

Basically i have my pattern to find

byte find = { 0x00, 0x48, 0x00 };

and

byte ddsHeaderDXT1 = { 0x44, 0x44, 0x53, 0x20, 0x7C, 0x00, 0x00, 0x00, 0x07, 0x10, 0x08, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x4E, 0x56, 0x54, 0x54, 0x06, 0x00, 0x02, 0x00, 0x20, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x44, 0x58, 0x54, 0x31, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10 };

the thing i wanna do is to search for my find array, once it's found, select all bytes from the beginning of the file to this find array included, and replace all this with my ddsHeaderDXT1 array.
The file can be pretty big but the pattern is always at the beginning (less than 500 first bytes), not always at the same offset and can be found only once.

I have already tried rene's code here but it doesn't do anything.
Also i get my file from OpenFileDialog and read its bytes

byte src = File.ReadAllBytes(ofdFilePath);

The following should do the trick:

public static bool TryFindAndReplace<T>(

    T source,

    T pattern,

    T replacement,

    out T newArray)

{

    if (source == null)

        throw new ArgumentNullException(nameof(source));



    if (pattern == null)

        throw new ArgumentNullException(nameof(pattern));



    if (replacement == null)

        throw new ArgumentNullException(nameof(replacement));



    newArray = null;



    if (pattern.Length > source.Length)

        return false;



    for (var start = 0; 

         start < source.Length - pattern.Length + 1; 

         start += 1)

    {

        var segment = new ArraySegment<T>(source, start, pattern.Length);



        if (Enumerable.SequenceEqual(segment, pattern))

        {

            newArray = replacement.Concat(source.Skip(start + pattern.Length))

                                  .ToArray();

            return true;

        }

    }



    return false;

}

Simple to read and therefore simple to understand. Its not the fastest solution by any means, but things need to be as fast as you need them to be, not faster.

If you need a more performant implementation, you can optimize from here.