substr_mb_vs_iconv.php

<?php     
    
/**                   
 * This example compares mb_string and iconv_string in the way that they're     
 * used in moodle's break_up_long_words() function. That is to say that it     
 * runs in a loop taking each character in turn                       
 */                                                                   
                                                                      
set_time_limit(0);                                                    
                                                                      
// An RSS feed description may realistically hit 5,000 characters     
$text = str_repeat('X', 5000);    
                             
$len = 1;                                                     
$charset = 'utf-8';                                           
$strlen = strlen($text);                                      
                                                              
/**                                                           
 * Check mb_substr                                            
 */                                                           
echo "<p>Checking mb_substr with a length of $strlen</p>";    
$timestart = microtime(true);                    
for ($i = 0; $i < $strlen; $i++) {                                                                                                  
    mb_substr($text, $i, $len, $charset);                                                                                           
}                                                                                                                                   
$timeend = microtime(true);                                                                                                         
$mbstringtime = $timeend - $timestart;                                                                                              
echo "<p>Took $mbstringtime seconds to process {$strlen} characters. That's " . ($mbstringtime / $strlen) . " seconds per character</p>";

/**                                                                                                                                 
 * Check iconv_substr                                                                                                               
 */
echo "<p>Checking iconv_substr with a length of $strlen</p>";    
$start = 0;
$timestart = microtime(true);                                    
for ($i = 0; $i < $strlen; $i++) {                               
    iconv_substr($text, $i, $len, $charset);                     
    $start++;
}   
$timeend = microtime(true);                                                                                                         
$iconvstringtime = $timeend - $timestart;                                                                                           
echo "<p>Took $iconvstringtime seconds to process {$strlen} characters. That's " . ($iconvstringtime / $strlen) . " seconds per character</p>";

$totaltime = abs($iconvstringtime - $mbstringtime);                                                                                 
echo "<p>Difference of {$totaltime} seconds - " . ($totaltime / $strlen) . " seconds per character</p>";