Processing Huge Files In C#
byte, c#, large-files, replace
Solution
Part of the problem may be that you're reading the stream one byte at a time. Try reading larger chunks and doing a replace on those. I'd start with about 8kb and then test with some larger or smaller chunks to see what gives you the best performance.
Problem
I have a 4Gb file that I want to perform a byte based find and replace on. I have written a simple program to do it but it takes far too long (90 minutes+) to do just one find and replace. A few hex editors I have tried can perform the task in under 3 minutes and don't load the entire target file into memory. Does anyone know a method where I can accomplish the same thing? Here is my current code: ``` public int ReplaceBytes(string File, byte[] Find, byte[] Replace) { var Stream = new FileStream(File, FileMode.Open, FileAccess.ReadWrite); int FindPoint = 0; int Results = 0; for (long i = 0; i < Stream.Length; i++) { if (Find[FindPoint] == Stream.ReadByte()) { FindPoint++; if (FindPoint > Find.Length - 1) { Results++; FindPoint = 0; Stream.Seek(-Find.Length, SeekOrigin.Current); Stream.Write(Replace, 0, Replace.Length); } } else { FindPoint = 0; } } Stream.Close(); return Results; } ``` Find and Replace are relatively small compared with the 4Gb "File" by the way. I can easily see why my algorithm is slow but I am not sure how I could do it better.