Method Types
Most file comparison tools find the longest common subsequence between two files. Any data not in the longest common subsequence is presented as an insertion or deletion.
In 1978, Paul Heckel published an algorithm that identifies most moved blocks of text. This is used in the IBM History Flow tool. Other file comparison programs find block moves.
Some specialized file comparison tools find the longest increasing subsequence between two files. The rsync protocol uses a rolling hash function to compare two files on two distant computers with low communication overhead.
File comparison in word processors is typically at the word level, while comparison in most programming tools is at the line level. Byte or character-level comparison is useful in some specialized applications.
Read more about this topic: File Comparison
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