Deprecate nfields and replace with numfields. * NEWS: Announce deprecation of nfields and addition of new function numfields. * container.txi: Add numfields to the manual. * oct-map.cc (octave_map::cat): Change %!tests to use numfields. * ov-struct.cc (Fnumfields): Function renamed from nfields. * scripts/deprecated/nfields.m: Add m-file which warns about nfields deprecation. * scripts/deprecated/module.mk: Add nfields.m to build system. * fieldnames.m: Change seealso link to point to numfields. * __isequal__.m: Use numfields to simplify code. * imwrite.m: Replace 'isempty (fieldnames (fmt))' with 'numfields (fmt) > 0' for clarity. * imageIO.m: Replace 'isempty (fieldnames (fmt))' with 'numfields (fmt) > 0' for clarity. * importdata.m: Use numfields to simplify code. * assert.m: Use numfields to simplify code.

--- a/scripts/io/importdata.m
+++ b/scripts/io/importdata.m
@@ -146,8 +146,7 @@
     ## i.e., output = output.onlyFieldLeft
 
     ## Update the list of fields
-    fields = fieldnames (output);
-    if (numel (fields) == 1)
+    if (numfields (output) == 1)
       output = output.(fields{1});
     endif
   endif