title: What are the other ways to determine two file contents are identical except for byte-by-byte checking?
body: <p>To compare byte by byte surely works. But I am wondering if there are any other <em>proven</em> way, say some kind of hashing that outputs unique values for each file. And if there are,  what are the advantages and disadvantage of each one in terms of time and memory footprint.</p>
  
  <p>By the way,  I found this previous thread <a href="https://stackoverflow.com/questions/784585/what-is-the-fastest-way-to-check-if-files-are-identical">What is the fastest way to check if files are identical?</a>. However, My question is not about speed, but alternatives.</p>
  
  <p>Please advise. Thanks.</p>