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Date: Sat, 22 Jul 2006 14:44:34 -0400
To: internals@lists.php.net
Subject: Re: [PHP-DEV] [v][sf]printf additions (#, E, g, G)
From: gwynne@skytag.com (Gwynne)

On Jul 20, 2006, at 3:21 PM, Marcus Boerger wrote:
>> I've wished there was a *printf() float specifier that wouldn't  
>> include
>> trailing zeros/point, as simply converting to string (echo, %s,  
>> etc.) can
>> result in scientific notation, which I *don't* want (%g in
>> convert_to_string()).  The only other way that would result in  
>> what I want
>> is number_format() with my "no-extra-zeros option" patch. ;-)  So  
>> I was
>> originally looking for how to NOT pad %f to the specified  
>> precision, then I
>> thought why not add more of the stuff from C?  (And I see it's  
>> marked "not
>> done" in formatted_print.c.)
>
>> Can/should I go ahead and add support for the # flag/specifier, g/ 
>> G, and E
>> (the missing compliment to e)?  Make everything work like C,  
>> except # used
>> with f/F, which would mean "remove trailing 0's/point" -- as C's  
>> behavior
>> with # and f (add point even when precision=0?) can be done in  
>> PHP.  (I
>> assume C's is for when precision is specified with * + parameter?)
> Having more conversion specifiers here won't hurt. If it can be done
> in a way compatible to other languages especially like C it should be
> done in that way. If PHP has already closed the way by choosing  
> opposite
> defaults the opposite should everntually also work.

While we're on the subject, one of my favorite personal patches to  
PHP is one that adds the %n specifier. The parameter to %n is a  
reference which recieves the total length of the string with all  
replacements so far. %n itself is replaced by nothing at all. You  
could do this with $n = strlen( $s = sprintf( blah blah blah ) ) +  
strlen( $s .= sprintf( the rest of the blah ) );, but it's a very  
nice shortcut if you need the replaced length in the middle of the  
conversion or for a situation like this (and the above doesn't work  
too well if you have positional params!):

printf( "Some processing message with %s replacements...%n", 'some', & 
$n );
// do some stuff here
print str_repeat( ' ', $n ) . "\rSome status text here that doesn't  
worry about whether the replaced text was longer.";

Here's the printf(3) manpage description for %n (MacOS X system, BSD  
manpage):

      n       The number of characters written so far is stored into  
the inte-
              ger indicated by the int * (or variant) pointer  
argument.  No
              argument is converted.

Any chance of getting this into PHP? I can provide a patch.

-- Gwynne, Daughter of the Code
"This whole world is an asylum for the incurable."