X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/4efef3db2fb1c3a20b83a67948e614d9b0c258dd..25cc0f2aada3e321e5f1c6d1e492a93d16da45b2:/lisp/files.el

diff --git a/lisp/files.el b/lisp/files.el
index b737c10158..db274e2782 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -4320,8 +4320,8 @@ the group would be preserved too."
 
 (defun file-name-sans-extension (filename)
   "Return FILENAME sans final \"extension\".
-The extension, in a file name, is the part that follows the last `.',
-except that a leading `.', if any, doesn't count."
+The extension, in a file name, is the part that begins with the last `.',
+except that a leading `.' of the file name, if there is one, doesn't count."
   (save-match-data
     (let ((file (file-name-sans-versions (file-name-nondirectory filename)))
 	  directory)
@@ -4336,15 +4336,16 @@ except that a leading `.', if any, doesn't count."
 
 (defun file-name-extension (filename &optional period)
   "Return FILENAME's final \"extension\".
-The extension, in a file name, is the part that follows the last `.',
-excluding version numbers and backup suffixes,
-except that a leading `.', if any, doesn't count.
+The extension, in a file name, is the part that begins with the last `.',
+excluding version numbers and backup suffixes, except that a leading `.'
+of the file name, if there is one, doesn't count.
 Return nil for extensionless file names such as `foo'.
 Return the empty string for file names such as `foo.'.
 
-If PERIOD is non-nil, then the returned value includes the period
-that delimits the extension, and if FILENAME has no extension,
-the value is \"\"."
+By default, the returned value excludes the period that starts the
+extension, but if the optional argument PERIOD is non-nil, the period
+is included in the value, and in that case, if FILENAME has no
+extension, the value is \"\"."
   (save-match-data
     (let ((file (file-name-sans-versions (file-name-nondirectory filename))))
       (if (and (string-match "\\.[^.]*\\'" file)