Edit report at http://bugs.php.net/bug.php?id=38437&edit=1
ID: 38437
Comment by: salsi at icosaedro dot it
Reported by: zizka at seznam dot cz
Summary: substr() - slightly change its contract
Status: Open
Type: Feature/Change Request
Package: Feature/Change Request
PHP Version: 5.1.4
New Comment:
The manual states that "If length is given and is 0, FALSE or NULL an
empty string will be returned.". This is not true, as substring($s,
$start, $length) seems to behave in a very unpredictable way with NULL
string, empty string and at the string boundaries when $length==0:
var_dump( substr("a", 0, 0) ); # => "", ok
var_dump( substr("a", 1, 0) ); # => FALSE rather than ""
var_dump( substr("", 0, 0) ); # => FALSE rather than ""
var_dump( substr(NULL, 0, 0) ); # => FALSE rather than ""
In my opinion, substr() should always return a string, possibly empty,
of length $length bytes provided that 0 <= $start and $start + $length
<= strlen($s). And then an empty string should be returned when
$length==0.
If $start is negative, the value $start = strlen($s) - $start should be
considered and the algorithm above applied.
The NULL value should be considered as the empty string "" as in PHP
tradition.
Previous Comments:
------------------------------------------------------------------------
[2006-08-12 20:34:14] zizka at seznam dot cz
Description:
------------
string substr ( string string, int start [, int length] )
Currently:
If string is less than *or equal* to start characters long, FALSE will
be returned.
I suggest:
If string is less than start characters long, FALSE will be returned.
The latter is more "ideologically clean". See the behavior of analogical
methods in Java, JavaScript, C, etc. E.g. I did some simple parser,
where the string of the form $<anything> is expected. I wanted to get
<anything>, so I did:
if($s !== '' && $s[0] == '$')
$s2 = substr($s, 1);
Then, behaved by Java's String.substring(), I wrote:
if($s2 === '')
// Replace $s2 with some default value;
After several minutes of searching for the bug, I noticed the fact
mentioned above.
Reproduce code:
---------------
substr("Ahoj", 4);
Expected result:
----------------
An empty string.
Actual result:
--------------
FALSE.
------------------------------------------------------------------------
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Edit this bug report at http://bugs.php.net/bug.php?id=38437&edit=1
