string.func.php

是个关于网格编程的程序

<?php
function get_substr($string,$start='0',$length='')
{
 $start = (int)$start;
 $length = (int)$length;
 $i = 0;
 if(!$string)
 {return;}
 if($start>=0) {
  while($i<$start) {
   if(ord($string[$i])>127) {
    $i = $i+2;
   } else {
    $i++;
   }
  }
  $start = $i;
  if($length=='') {
   return substr($string,$start);
  } 
  elseif($length>0) {
   $end = $start+$length;
   while($i<$end) {
    if(ord($string[$i])>127) {
     $i = $i+2;
    } else {
     $i++;
    }
   } if($end != $i-1) {
    $end = $i;
   } else {
    $end--;
   }
   $length = $end-$start;
   return substr($string,$start,$length);
  } elseif($length==0) {
   return;
  } else {
   $length = strlen($string)-abs($length)-$start;
   return get_substr($string,$start,$length);
  }
 } else {
  $start = strlen($string)-abs($start);
  return get_substr($string,$start,$length);
 } 
}
?>