SELECT value 
FROM unnest(array(0,1,2,3,4,5))
WHERE value < 3;

Parse error: no query solution (not sure what the behavior should be. I hoped for an other result)

SELECT value
FROM unnest (1);

crashes SQLite without error

This query in SQLiteSpy and the equivalent in Notepad++ SELECT regexp_replace('abcde','[bd]','_') yields the result: a_c_e as I would expect.

The extension when added to SQLite Expert Personal 64 gives a different result: a_cde

Is the app wrong or the extension?

Here is a extension for making PostScript tokens (public domain):

jar:http://www.dessus.com/files/sqlite3extensions.zip!/pstoken.c

Note, that PostScript does not distinguish text/blobs; they are the same type in PostScript. However, this extension uses a different syntax for them.

If you add -Wall gcc complains about a few things, see below. Might be good to fix?

$ gcc -Wall -fPIC -shared src/sqlite3-unicode.c -o dist/unicode.so
src/sqlite3-unicode.c:22: warning: ignoring #pragma warning  [-Wunknown-pragmas]
   22 | #pragma warning(disable : 4305 13 90)
      | 
src/sqlite3-unicode.c:31:32: warning: multi-line comment [-Wcomment]
   31 | #define SQLITE3_UNICODE_UNACC  // ~ 30KB increase \
      |                                ^
src/sqlite3-unicode.c: In function ‘sqlite3StrNICmp’:
src/sqlite3-unicode.c:5278:12: warning: operation on ‘ua’ may be undefined [-Wsequence-point]
 5278 |         ua = GlogUpperToLower(ua);
      |            ^
src/sqlite3-unicode.c:5279:12: warning: operation on ‘ub’ may be undefined [-Wsequence-point]
 5279 |         ub = GlogUpperToLower(ub);
      |            ^
src/sqlite3-unicode.c: In function ‘sqlite3StrNICmp16’:
src/sqlite3-unicode.c:5292:12: warning: operation on ‘ua’ may be undefined [-Wsequence-point]
 5292 |         ua = GlogUpperToLower(ua);
      |            ^
src/sqlite3-unicode.c:5293:12: warning: operation on ‘ub’ may be undefined [-Wsequence-point]
 5293 |         ub = GlogUpperToLower(ub);
      |            ^
At top level:
src/sqlite3-unicode.c:4917:33: warning: ‘likeInfoAlt’ defined but not used [-Wunused-const-variable=]
 4917 | static const struct compareInfo likeInfoAlt = {'%', '_', 0, 0};
      |                                 ^~~~~~~~~~~
src/sqlite3-unicode.c:4911:33: warning: ‘globInfo’ defined but not used [-Wunused-const-variable=]
 4911 | static const struct compareInfo globInfo = {'*', '?', '[', 0};
      |                                 ^~~~~~~~
src/sqlite3-unicode.c:4340:36: warning: ‘sqlite3UpperToLower’ defined but not used [-Wunused-const-variable=]
 4340 | SQLITE_PRIVATE const unsigned char sqlite3UpperToLower[] = {
      |                                    ^~~~~~~~~~~~~~~~~~~

The incubator contains SQLite extensions which haven't yet made their way to the main set. They may be untested, poorly documented, too broad, too narrow, or without a well-thought API. Think of them as candidates for the standard library.

See the full extension list below and vote for your favorites! We'll refactor and merge popular ones into the main set.

• array: one-dimensional arrays.
• besttype: convert string value to numeric.
• bloom: a fast way to tell if a value is already in a table.
• btreeinfo, memstat, recsize and stmt: various database introspection features.
• cbrt and math2: additional math functions and bit arithmetics.
• classifier: binary classifier via logistic regression.
• closure: navigate hierarchic tables with parent/child relationships.
• compress and sqlar: compress / uncompress data.
• cron: match dates against cron patterns.
• dbdump: export database as SQL.
• decimal, fcmp and ieee754: decimal and floating-point arithmetic.
• envfuncs: read environment variables.
• interpolate: interpolate missing values for timestamped measurements.
• isodate: additional date and time functions.
• lines: read files line-by-line
• path: parsing and querying paths
• pearson: Pearson correlation coefficient between two data sets.
• pivotvtab: pivot tables.
• prefixes: generate string prefixes.
• rotate: string obfuscation.
• spellfix: search a large vocabulary for close matches.
• stats2 and stats3: additional math statistics functions.
• text2: additional string functions.
• uint: natural string sorting and comparison.
• unhex: reverse for hex().
• unionvtab: union similar tables into one.
• xmltojson: convert XML to JSON string.
• zipfile: read and write zip files.
• zorder: map multidimensional data to a single dimension.

Meanwhile, you can download compiled incubator extensions as they are and use them if you like. Or add a new extension.

P.S. This issue is for extension announcements only, so please don't comment on it. Happy to discuss any extension-related questions in separate issues.

It would be much useful for me to benefit from an equivalent function to the CONV() one in MySQL, which converts numbers from one numeric base number system to another.

Hope you'll consider adding such function, and in any case, thank you very much for investing your time and efforts into this nice project ! Cheers