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.

getSizeStringBytes.php

<?php
/**
*
* @param string $str The string to compute number of bytes
*
* @return The length in bytes of the given string.
*/
function getSizeStringBytes($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{$c});
  switch(true){
  case(($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
   $d+=2;
   break;
  case(($ord_var_c & 0xF0) == 0xE0):
   // characters U-00000800 - U-0000FFFF, mask 1110XXXX
   $d+=3;
   break;
  case(($ord_var_c & 0xF8) == 0xF0):
   // characters U-00010000 - U-001FFFFF, mask 11110XXX
   $d+=4;
   break;
  case(($ord_var_c & 0xFC) == 0xF8):
   // characters U-00200000 - U-03FFFFFF, mask 111110XX
   $d+=5;
   break;
  case(($ord_var_c & 0xFE) == 0xFC):
   // characters U-04000000 - U-7FFFFFFF, mask 1111110X
   $d+=6;
   break;
   default:
   $d++;
  };
 };
 return $d;
}
?>