Re: gawk bug - 'is equal' is faulty for string

[Andrew J. Schorr]

On Mon, Jan 27, 2020 at 03:32:19PM +0100, Manuel Collado wrote:
> I think this is the expected result in both cases. The
> "$4==cversion" comparison is a numeric one, because both $4 and
> cversion values come from input data and look as numbers.
> 
> Please search for "numeric string" or "strnum" in the gawk manual.

Manuel is correct. You can force a string comparison by concatenating one of
the operands with "", e.g. (y == x"").  The chart below from the
docs is useful for understanding how comparison works. And in newer
versions of gawk, the typeof function is useful for getting a better
understanding of what's going on.

https://www.gnu.org/software/gawk/manual/html_node/Variable-Typing.html

   When two operands are compared, either string comparison or numeric
comparison may be used.  This depends upon the attributes of the
operands, according to the following symmetric matrix:

        +----------------------------------------------
        |       STRING          NUMERIC         STRNUM
--------+----------------------------------------------
        |
STRING  |       string          string          string
        |
NUMERIC |       string          numeric         numeric
        |
STRNUM  |       string          numeric         numeric
--------+----------------------------------------------

Regards,
Andy