Re: ctype second opinions

On Fri, 19 Jul 2002, Pierre-Alain Joye wrote: > On Fri, 19 Jul 2002 08:41:53 -0500 (CDT) > Brent Cook <busterb@mail.utexas.edu> wrote: > > > Dear all, > > > > I would like your opinion, please. I'm currently arguing a bug in the > > PHP database, http://bugs.php.net/bug.php?id=18428, and > > basically feel > > that I have made the correct choice, while the PHP developer feels > > otherwise. > > > > The ctype functions in PHP currently return TRUE on an empty string. For > > instance, ctype_alpha('a') == TRUE, ctype_alpha('1') == FALSE, > > ctype_alpha('') == TRUE. I argued that since no characters in an empty > > string match the criteria, an empty string should return FALSE. The > > developer argued that "in an empty string every of the 0 charactetrs > > matches the (criteria)", so it should return TRUE. > > afaik, ctype_alpha checks only the type, returning true if the param is > an alhatype. An empty string is an alpha. That s a fact. Yes, that is what it does currently. What about: ctype_space(''), ctype_print('') or ctype_cntrl('') these also return true. Does an empty string intuitively contain spaces, printable characters or control characters? > > if (strlen($c) && ctype_alpha($c)) > > can be replaced by : > if ( ctype_alpha($c) && strlen($c) ) > > You can check the string length only if $c is a string. In this case, I know that the argument is a string; rather this ordering takes advantage of short-circuit logic to avoid calling ctype_isalpha() if the string is zero length. The whole of the logic that I am trying to convey here similar to: $string = 'This is a string'; $i = 0; while ($string[$i] != '') { $token = ''; while (strlen($string[$i]) && ctype_alpha($string[$i]) { $token .= $string[$i]; ++$i; } $tokens[] = $token; ++$i; } Without checking strlen, this snippet will go into an infinite loop when it reaches the end. And don't say to use strtok(), I'm doing more than just this ;) - Brent