[PHP-DOC] Bug #18428 Updated: ctype functions return TRUE on zero-length strings From: busterb <email protected>
Date: 07/19/02

 ID: 18428
 Updated by: busterb <email protected>
 Reported By: busterb <email protected>
 Status: Closed
 Bug Type: Documentation problem
 Operating System: Linux
 PHP Version: 4CVS-2002-07-19
 New Comment:

I must have overlooked the extension while it was
experimental or not had a need for it then. Anyway, I
reread the documentation, and realized that I had missed
ctype's behavior for integers. ctype_xxx(ord($c)), does
what I need.

Previous Comments:
------------------------------------------------------------------------

[2002-07-19 11:58:39] hholzgra <email protected>

"If there is nothing, there is nothing to match."

i'm more for "if theres nothing, there's nothing to fail"

and comparing this to the ctype functions just makes
no sense, C operates on single characters only and
the behaviour of the PHP functions on single characters
(either single character string or integer character code)
exactly matches the c behavior

if i was to implement the functions now i would
maybe consider the "empty is false" variant the
better one, but back then i didn't

the extension has been marked EXPERIMENTAL for
a loooooong time and nobody objected, now it
has been declared stable and so it will be

------------------------------------------------------------------------

[2002-07-19 09:03:35] busterb <email protected>

While I accept the backwards-compatibility argument
conditionaly, the rest of the reasoning, i.e. "can't see
the contradiction here as in an empty string every of the
0 charactetrs matches the criteriy ..." is hard to
believe.
 
If there is nothing, there is nothing to match. With the C
versions of these functions, it is obviously not possible
to run into this situation; essentially they _require_ a
'string' that is one character long, taking a character
argument. Therefore, these functions should have required
that the string be at least one character long in the
first place. It is unfortunate that what inconsistent
behavior with the real ctype functions must be maintained
for backwards compatibility, especially for an extension
that is so young (it has only been a default option since
4.2). If there were ever a time to correct its behavior,
better sooner than later.
 
I had included ctype_ equivalent functions in PEAR under
DBA/ctype.php due to the fact that these functions are not
commonly included with PHP installations. I wrote that
exhibit what I feel is the correct behavior before
noticing the ctype functions built-in to PHP. Should I
now rewrite them so that they and are inconsistent with
C's ctype functions but compatible with PHP's?

------------------------------------------------------------------------

[2002-07-19 06:01:35] hholzgra <email protected>

an empty string is a string ;)

the documentation says:
" When called with a string argument they will check every character in
the string and will only return TRUE if every character in the string
matches the requested criteria. "

can't see the contradiction here as in an empty string every of the 0
charactetrs matches the criteriy ...

will add a note about that in the documentation,
but the behaviour will not change for backwards
compatibility reasons

------------------------------------------------------------------------

[2002-07-19 01:12:35] busterb <email protected>

The PHP ctype functions return TRUE when passed a zero
length string. This is incorrect behavior; see the
documentation for the contradiction. This is not an issue
with the C ctype functions, since they deal with
characters, which cannot be zero-length.
 
The following patch corrects this behavior
--- ctype.c 2002-07-18 23:58:02.000000000 -0500
+++ ctype_fixed.c 2002-07-18 23:57:48.000000000
-0500
@@ -102,8 +102,11 @@
                { \
                        char *p; \
                        int n, len; \
- p=Z_STRVAL_P(c); \
                        len = Z_STRLEN_P(c); \
+ if (!len) { \
+ RETURN_FALSE; \
+ } \
+ p = Z_STRVAL_P(c); \
                        for(n=0;n<len;n++) { \
                                if(!iswhat(*p++))
RETURN_FALSE; \
                        } \
 

------------------------------------------------------------------------ 

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