strrchr with needle with multiple characters

Hi,

On Mon, 2 Sept 2024 at 12:20, Vincent Langlet misterdeviling@gmail.com
wrote:

I was today old when I discovered the big difference between strchr and
strrchr in the way they handle needle with multiple characters.

It's explained in the doc
https://www.php.net/manual/en/function.strrchr.php

• If needle contains more than one character, only the first is used.
  This behavior is different from that of strstr()
  https://www.php.net/manual/en/function.strstr.php.

You can see an example https://3v4l.org/7j5ab

I feel like this behavior has no benefit (if I want to look for the first
character, I can pass substr($needle, 0, 1) instead) and is just
error-prone.

Is there a reason for such behavior ? Would it be easy to change it (I
have no knowledge at all in C and in the existing PHP code) ?

It is a bit ambiguous, I'll give you that, albeit you can pass a string to
str(r)chr only the first character is used, these are literally similar to
their C counterparts

https://www.tutorialspoint.com/c_standard_library/c_function_strchr.htm
https://www.tutorialspoint.com/c_standard_library/c_function_strrchr.htm

see the second argument handles one character at a time.

Cheers.

I was today old when I discovered the big difference between strchr and
strrchr in the way they handle needle with multiple characters.

It's explained in the doc https://www.php.net/manual/en/function.strrchr.php

• If needle contains more than one character, only the first is used. This
  behavior is different from that of strstr()
  https://www.php.net/manual/en/function.strstr.php.

You can see an example https://3v4l.org/7j5ab

I feel like this behavior has no benefit (if I want to look for the first
character, I can pass substr($needle, 0, 1) instead) and is just
error-prone.

Is there a reason for such behavior ? Would it be easy to change it (I have
no knowledge at all in C and in the existing PHP code) ?

strchr() is an alias of strstr(), and I would always use the latter
name, because strchr() is indeed confusing. Anyhow, strstr() is very
useful in C, but not so much in PHP, since in PHP it will always
allocate a new string, even if that is not needed.

Now, comparing strstr() and strrchr() is of course still possible, but
different behavior is less astonishing. Of course, strrchr() could warn
or even throw if $needle has more than one character, but that may
unnecessarily break code for a small benefit.

Christoph