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elisp: Comparing Text

 
 31.3 Comparing Text
 ===================
 
 This function lets you compare portions of the text in a buffer, without
 copying them into strings first.
 
  -- Function: compare-buffer-substrings buffer1 start1 end1 buffer2
           start2 end2
      This function lets you compare two substrings of the same buffer or
      two different buffers.  The first three arguments specify one
      substring, giving a buffer (or a buffer name) and two positions
      within the buffer.  The last three arguments specify the other
      substring in the same way.  You can use ‘nil’ for BUFFER1, BUFFER2,
      or both to stand for the current buffer.
 
      The value is negative if the first substring is less, positive if
      the first is greater, and zero if they are equal.  The absolute
      value of the result is one plus the index of the first differing
      characters within the substrings.
 
      This function ignores case when comparing characters if
      ‘case-fold-search’ is non-‘nil’.  It always ignores text
      properties.
 
      Suppose you have the text ‘foobarbar haha!rara!’ in the current
      buffer; then in this example the two substrings are ‘rbar ’ and
      ‘rara!’.  The value is 2 because the first substring is greater at
      the second character.
 
           (compare-buffer-substrings nil 6 11 nil 16 21)
                ⇒ 2
 

Info Catalog elisp: Buffer Contents elisp: Text elisp: Insertion