# [PATCH] substr() returns false

- Thread: https://externals.io/message/5552
- Original archive: https://news-web.php.net/php.internals/5552
- Started by Morten Poulsen on 2003-11-19T13:39:09+00:00
- Messages: 2
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## #5552 — Morten Poulsen — 2003-11-19T13:39:09+00:00

URL: https://externals.io/message/5552#5552

Hi,

Even though this is documented, it is strange behaviour: If the from
parameter to `substr()` is at, or past, the end of the input string, the
function returns false.

The function is documented as
string substr ( string string, int start [, int length])

IMHO `substr()` should either

1) be changed to do like Perl, which returns an error only if start is
_beyond_ the end (not _at_):
(from http://www.perldoc.com/perl5.6/pod/func/substr.html)
my $null = substr $name, 6, 2;  # returns '' (no warning)
my $oops = substr $name, 7;     # returns undef, with warning

2) be changed to return an empty string, if start is either at or beyond
the end of the input string.

I have attached patches for both solutions.

If you don't change it to be like Perl, I think it should be noted in
the documentation (as with `chop()`).
If, on the other hand, it _is_ changed to behave like Perl, I think it
should be emphasized that you are not guaranteed that the result is a
string, because this will cause (eg. has caused us) problems when using
the result as part of the $data array to PEAR DB::execute().

Happy hacking,
Morten

-- 
Morten Poulsen <morten-Qg2caEh8@afdelingp.dk>
http://www.afdelingp.dk/

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## #5565 — Andi Gutmans — 2003-11-19T18:30:25+00:00

URL: https://externals.io/message/5552#5565 · In reply to: #5552

Not sure if/how this should be changed.
Isn't it a mistake to give a start position at the end or beyond the 
string? In this case, doesn't it make sense to return false?

Andi

At 02:39 PM 11/19/2003 +0100, Morten Poulsen wrote:
>Hi,
>
>Even though this is documented, it is strange behaviour: If the from
>parameter to `substr()` is at, or past, the end of the input string, the
>function returns false.
>
>The function is documented as
>string substr ( string string, int start [, int length])
>
>IMHO `substr()` should either
>
>1) be changed to do like Perl, which returns an error only if start is
>_beyond_ the end (not _at_):
>(from http://www.perldoc.com/perl5.6/pod/func/substr.html)
>my $null = substr $name, 6, 2;  # returns '' (no warning)
>my $oops = substr $name, 7;     # returns undef, with warning
>
>2) be changed to return an empty string, if start is either at or beyond
>the end of the input string.
>
>I have attached patches for both solutions.
>
>If you don't change it to be like Perl, I think it should be noted in
>the documentation (as with `chop()`).
>If, on the other hand, it _is_ changed to behave like Perl, I think it
>should be emphasized that you are not guaranteed that the result is a
>string, because this will cause (eg. has caused us) problems when using
>the result as part of the $data array to PEAR DB::execute().
>
>Happy hacking,
>Morten
>
>--
>Morten Poulsen <morten-Qg2caEh8@afdelingp.dk>
>http://www.afdelingp.dk/