sscanf function bug

[abbuaus]

Description

The following code:

<?php
$str = "aaa\bbb\ccccDddd";
sscanf($str,"aaa\bbb\%sDddd",$str_1);
echo $str_1;
exit();

Resulted in this output:

ccccDddd

But I expected this output instead:

cccc

PHP Version

PHP 8.2.5 (cli) (built: Apr 14 2023 04:39:46) (NTS)

Operating System

debian 11.7

[nielsdos]

From https://www.php.net/manual/en/function.sscanf

s stops reading at any whitespace character.

Then the Dddd in the format string is considered trailing data and ignored.

This function sscanf is modelled after the C function with the same name. This behaviour is the same how C behaves.
Therefore this is not a bug.
You should probably use regex matching instead of sscanf for your use-case.

[hakre]

The report is indeed not valid, albeit the rationale given as I read it was not explaining it right (my guess, flipping the expected/actual order):

%s matches a sequence of non-white-space characters, the directive afterwards "Dddd" is just a matching failure:

aaa\bbb\ccccDddd

aaa\bbb\%sDddd
          ^^^^ unmatched

as the directive aaa\bbb\ is not a matching failure, %s is still considered for matching, and it matches and assigns ccccDddd to $str_1

as the OP reports that as unexpected but cccc as expected, it is either that at maximum 4 characters were expected, %4c, or only the latin-lower-case-c character was expected, %[c], or a variation of both.