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in reply to What is truth? (Curiosity corner)

What about "0E0" for zero-but-true? Doesn't it work the same way? 
perl -wle 'print 23+"0E0" if "0E0"'
23

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Re: Re: What is truth? (Curiosity corner)
by robin (Chaplain) on Dec 21, 2001 at 07:24 UTC
    Yeah, it does indeed. I'm not quite sure why "0 but true" is often preferred. Maybe because it's more explicit about its intention?
[reply]
      "0E0" is used by the DBI (and DBD's) for eg. $sth->execute when the SQL-statement processed 0 rows but did not error.

      This allows constructions like my $rows=$sth->execute or die "SQL error" ( Of course this would be expressed better using $dbh->{RaiseError} = 1).

      The relevant part of the DBI documentation states:

      For a non-`SELECT' statement, `execute' returns the number of rows affected, if known. If no rows were affected, then `execute' returns "`0E0'", which Perl will treat as 0 but will regard as true. Note that it is not an error for no rows to be affected by a statement. If the number of rows affected is not known, then `execute' returns -1.

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