Posted by Taras_96 on 01/23/07 12:46

Hi everyone,

I'm lost as to the meaning of a function being 'binary-safe'. The
Wikipedia entry states that:

"essentially one that treats its input as a raw stream of data without
any specific format" and that

"Most functions using any special or markup characters, such as escape
codes or those that expect null-terminated strings are not binary
safe".

This to me implies that the function need not know what the bytes
represent, it operates on the data as a raw byte stream. If this is the
case, I can't see how strpos would be binary-safe (it is documented as
such). For example, by calling 'strpos('a','cat')', surely the function
itself must know that the strings 'a' and 'cat' are null terminated,
and thus according to the wikipedia definition (since special
significance is given to the null character) the function is not binary
safe. To further illustrate my point, what would happen if the strings
that were passed in were encoded in UCS-2, where the string 'a' would
be encoded as '00 61' (assuming big endian encoding) - wouldn't strpos
recognise the '00' byte as an ASCII null character, and conclude that
the first parameter was simply an empty string?

This post:
http://groups.google.com/group/php.general/browse_thread/thread/c401d89a4a68e94b/e7820fe40145ac7b?lnk=st&q=what+is+%22binary+safe%22&rnum=4&hl=en#e7820fe40145ac7b
offers a different definition, which doesn't make much sense to me.

To add to the confusion, other websites suggest that 'binary-safe'
simply implies that the function can operate on the given data without
altering it.

What exactly is binary-safe in the PHP context? Could examples of
binary-safe and non binary-safe functions be given?

Thanks

Taras

[Back to original message]