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Markus Bergholz fff8a814cc add sed help 2 years ago
LICENSE Initial commit 2 years ago
Makefile change compile options 2 years ago update readme 2 years ago
fastcompare.c add sed help 2 years ago


use make build to compile


fastcompare file1 file2


fastcompare is designed to compare line-based content (order doesn’t matter) of very large ASCII files.

For the 1st file, it will generate crc32 hashes for each line (so it is more memory efficient when you take the smaller file as the 1st file. But this has no affect on the speed). Now it will iterate over the 2nd file, build a temporary crc32 hash and do a binary search in the hash array.


still under construction


  • use struct array to carry line index after sorting
  • use optional other hashing algorithms to lower the risc of collisions


  • duplicates lines from file one, can be marked as “not included in” 2nd file (only when the 2nd one hasn’t the equal number of this line).