boyer-moore

Main features performs the comparisons from right to left; preprocessing phase in O ( m + ) time and space complexity; searching phase in O ( m n ) time complexity; 3 n text character comparisons in the worst case when searching for a non periodic pattern; O ( n / m ) best performance. Description The Boyer-Moore algorithm is considered as the most efficient string-matching algorithm in usual applications. A simplified version of it or the entire algorithm is often implemented in text editors for the «search» and «substitute» commands. The algorithm scans the characters of the pattern from

Is there a working example of the Boyer-Moore string search algorithm in C? I've looked at a few sites, but they seem pretty buggy, including wikipedia. Thanks. The best site for substring search algorithms: http://igm.univ-mlv.fr/~lecroq/string/ There are a couple of implementations of Boyer-Moore-Horspool (including Sunday's variant) on Bob Stout's Snippets site. Ray Gardner's implementation in BMHSRCH.C is bug-free as far as I know 1 , and definitely the fastest I've ever seen or heard of. It's not, however, the easiest to understand -- he uses some fairly tricky code to keep the inner loop

I have been trying to understand shift rules in Boyer–Moore string search algorithm but haven't understood them. I read here on wikipedia but that is too complex ! It will be of great help if someone lists the rule in a simple manner. In the Boyer-Moore algorithm, you start comparing pattern characters to text characters from the end of the pattern. If you find a mismatch, you have a configuration of the type ....xyzabc.... <-text ....uabc <- pattern ^ mismatch Now the bad character shift means to shift the pattern so that the text character of the mismatch is aligned to the last occurrence of

Boyer-Moore is probably the fastest non-indexed text-search algorithm known. So I'm implementing it in C# for my Black Belt Coder website. I had it working and it showed roughly the expected performance improvements compared to String.IndexOf() . However, when I added the StringComparison.Ordinal argument to IndexOf , it started outperforming my Boyer-Moore implementation. Sometimes, by a considerable amount. I wonder if anyone can help me figure out why. I understand why StringComparision.Ordinal might speed things up, but how could it be faster than Boyer-Moore? Is it because of the the

I need three fast-on-large-strings functions: fast search, fast search and replace, and fast count of substrings in a string. I have run into Boyer-Moore string searches in C++ and Python, but the only Delphi Boyer-Moore algorithm used to implement fast search and replace that I have found is part of the FastStrings by Peter Morris, formerly of DroopyEyes software, and his website and email are no longer working. I have already ported FastStrings forward to work great for AnsiStrings in Delphi 2009/2010, where a byte is equal to one AnsiChar, but making them also work with the String