In total, this will increase the sequence about 3.57 times!. Besides you will use/need an extra byte for separating the numeric representations. In the purposed solution, each byte will take an average of 2.57 bytes (depending on the number of decimal digits of each byte: (1 * 10 / 256) + (2 * 90 /256) + (3 * 156 / 256)). MemoryĪside from some founded performance disadvantages, there is a memory disadvantage as well by converting each byte to a decimal string representation. I guess, that you might presume that the native algorithms for the PowerShell string representation and methods (operators) like -Like are meanwhile completely squeezed. String manipulations are usually expensive but re-initializing a LINQ call is apparently pretty expensive as well. I dislike the idea of converting byte sequences to character sequencesĪt all (I'd better have functionality to match byte (or other)Ĭonversion-to-character-strings-implying solutions this seems to be Just formalizing my comments and agreeing with your comment: NET (especially that particual implementation for sequences of characters exists). a common method to match sequences with any item type: integer, object, etc). Sadly, I haven't found a way to match sequences universally (i.e. On older PowerShell, you can use: ::GetEncoding(28591).

1250, 101 fit, but various species of Unicode (including the default BOM-less UTF-8) don't, because they convert any non-well-formed code-unit to the same replacement character (U+FFFD)). Of course, we need to use the same encoding for both the file and fragment, and the encoding must be really binary-safe (e.g. NET System.Strings) when we specify binary-safe encoding. any bytes can be successfully matched by PowerShell strings (in fact. I've determined that the following can work as a workaround: (Get-Content $filepath -Raw -Encoding 28591).IndexOf($fragment) Function Find-Bytes(]$Bytes, ]$Search, $Start, $All) Use the -All switch to return the remaining indexes of any other search sequences found.

If the search sequence is not found a $Null ( ::Value) is returned.ĭefines where to start searching in the Bytes sequence (default: 0)īy default, only the first index found will be returned. Returns the index of where the -Search byte sequence is found in the -Bytes byte sequence. In my testing, the below Find-Bytes function is about 20% till twice as fast as the function in your question: Find-Bytes

, 0, 0, 1).īased on this, it shows again (I have also proven this in some other answers) that native PowerShell commands aren't that bad and possibly could even outperform. , 0, 0, 0) and a SearchArray of the same bytes ending with a different byte (e.g. A worse case scenario for my assumption will be a ByteArray existing of the same bytes (e.g. (So, how random are your given binary sequences actually?, If they are far from random, I think you need to add some more details to your question). Note that this also implies that the chance a 500Kb random sequence exists in a 100Mb random sequence is virtually zero. In other words, the performance of everything outside the inner loop (but in the outer loop) is almost as important as what is in the inner loop! Meaning that the inner loop will only run about 1.004 times as much as the outer loop. In that case you don't have to look further, and if it does match, the chance that the second byte also matches is 1/256 2, etc. There is only a 1/256 chance that each byte in the ByteArray will match the first byte of the SearchArray. Net command for this so far, it is quiet understandable that several semi-.Net solutions are being purposed instead but I believe that this will cause some undesired overhead for a universal function.Īssuming that you ByteArray (the byte array being searched) and SearchArray (the byte array to be searched) are completely random. Net or Linq.Īnyways, the fact that nobody is able to find the single assumed.

NET' to accept an answer, it probably not going to happen, the same quest exists for StackOverflow searches in combination with C#. Btw, if you looking for a positive response to the question ' I believe that it must exist in. It is not usual to do so, but the universal question intrigues me and the approach and information of my initial ' using -Like' answer is completely different.

Powershell grep zipped files