How to read, search and change file by bytes?

Question

Does anyone know how to find more bytes after I found the byte sequence of my variable?

for example: in the file will look like this: 6261725610

I’ll look for that:

byte[] findBytes = { 0x62, 0x61, 0x72 };

and wanted to return this:

byte[] resultado = { 0x62, 0x61, 0x72, 0x56, 0x10 };

Taking advantage, how do I subtract the last byte?

for example this:

byte[] findBytes = { 0x62, 0x61, 0x72, 0x56, 0x10 };

had seen this:

byte[] findBytes = { 0x62, 0x61, 0x72, 0x56, 0x8 };

Answer 1

Try using this library I developed - Sequences -, makes collection handling much easier. It has an API identical to Scala collections.

var bytes = new byte[] {0x01, 0x02, 0x03, 0x62, 0x61, 0x72, 0x56, 0x10}.AsSequence();
var find = new byte[] {0x62, 0x61, 0x72};


var index = bytes.IndexOfSlice(find);
var remaining = bytes.Skip(index);     //retorna 0x62, 0x61, 0x72, 0x56, 0x10

(I added a few bytes at the beginning of the array to better demonstrate the search for the sub-sequence).

• AsSequence converts the byte[] in a ISequence<byte>
• IndexOfSlice does an efficient search by sub-sequence using the algorithm KMP
• Skip Release the elements that appear before the sub-sequence and return the remaining ones.

To replace the last element:

var replaced = remaining.Init.Append(0x8);   // retorna 0x62, 0x61, 0x72, 0x56, 0x8

• Init returns the sequence without the last element
• Append joins an element at the end of the sequence.

Links

• Nuget: http://www.nuget.org/packages/Sequences
• API: http://diogocastro.com/Sequences/