Should there be something like 'bytelen' (along with 'strlen')?

Question

In my opinion the 'strlen' function should only return the number of characters in a string. Nothing else. And it does, whether it counts ASCII characters or Unicode characters. A character is a character, pointing to a given position on an ASCII table or a UTF-8 table. Nothing more.

If you would like to know, for whatever reason, the byte-length of a string, then you should use a differtent function. I am a newby in PHP scripting, so I did not find that function yet. (Should be something like 'bytelen()'?)

Answer 1

mb_strlen() does what you're after.

Answer 2

/** 
     * Count the number of bytes of a given string. 
     * Input string is expected to be ASCII or UTF-8 encoded. 
     * Warning: the function doesn't return the number of chars 
     * in the string, but the number of bytes. 
     * 
     * @param string $str The string to compute number of bytes 
     * 
     * @return The length in bytes of the given string. 
     */ 
    function strBytes($str) 
    { 
      // STRINGS ARE EXPECTED TO BE IN ASCII OR UTF-8 FORMAT 

      // Number of characters in string 
      $strlen_var = strlen($str); 

      // string bytes counter 
      $d = 0; 

     /* 
      * Iterate over every character in the string, 
      * escaping with a slash or encoding to UTF-8 where necessary 
      */ 
      for ($c = 0; $c < $strlen_var; ++$c) { 

          $ord_var_c = ord($str{$d}); 

          switch (true) { 
              case (($ord_var_c >= 0x20) && ($ord_var_c <= 0x7F)): 
                  // characters U-00000000 - U-0000007F (same as ASCII) 
                  $d++; 
                  break; 

              case (($ord_var_c & 0xE0) == 0xC0): 
                  // characters U-00000080 - U-000007FF, mask 110XXXXX 
                  // see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8 
                  $d+=2; 
                  break; 

              case (($ord_var_c & 0xF0) == 0xE0): 
                  // characters U-00000800 - U-0000FFFF, mask 1110XXXX 
                  // see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8 
                  $d+=3; 
                  break; 

              case (($ord_var_c & 0xF8) == 0xF0): 
                  // characters U-00010000 - U-001FFFFF, mask 11110XXX 
                  // see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8 
                  $d+=4; 
                  break; 

              case (($ord_var_c & 0xFC) == 0xF8): 
                  // characters U-00200000 - U-03FFFFFF, mask 111110XX 
                  // see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8 
                  $d+=5; 
                  break; 

              case (($ord_var_c & 0xFE) == 0xFC): 
                  // characters U-04000000 - U-7FFFFFFF, mask 1111110X 
                  // see http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8 
                  $d+=6; 
                  break; 
              default: 
                $d++;    
          } 
      } 

      return $d; 
    } 

Answer 3

Yes, that would be most logical design. However, PHP has not been planned to support multibyte charsets from the beginning. Instead, it's been evolving along the years in a sort of chaotic manner. You've tagged your question as PHP 4 but PHP 5 does not have a decent Unicode support yet (and I don't think it'll change in a nearby future).

There're a few reasons for this anyway:

• PHP is not a closed-source commercial product owned by a company with a centralized design controlled by enterprise rules.

• PHP was released in 1995 as a personal project by someone who needed some functionality in his static home page: at that time, it had no need for Unicode support.

• If you modify core functions like strlen() you must do it in a way that it doesn't break previous functionality. It's not easy. Writing a new separate function is much easier.

Update

Sorry, I forgot the second part of your question. If you need to handle Unicode strings you have to use a separate set of functions:

• http://es.php.net/manual/en/book.mbstring.php

You might also find these chapters interesting:

• http://es.php.net/manual/en/book.iconv.php
• http://es.php.net/manual/en/book.unicode.php

Please take note of the PHP version required by each function you are planning to use; PHP 4 is pretty old.

Answer 4

If I'm not grossly misunderstanding you, then strlen() is your 'bytelen()', as alluded to in the other responses here.

strlen() itself has no support for utf-8 or other multi-byte character sets; if you want a proper strlen(), you'll need mb_strlen().

Pentium10's function strBytes($str), from glancing over it (not testing) looks like it would be a good alternative if you know your encoding is utf-8 and you're stuck with a super low version of PHP4 for some reason.

(And I do recommend taking a look at Álvaro G. Vicario's post for the reasons behind this behaviour. Proper, native UTF-8 support is due to come with PHP6.)