/*
  

  $a为路径1，
  

  $b为路径2,
  

  $c为路径1的搜索位置，
  

  $d为路径2的搜索位置，
  

  */
  

  function abc($a,$b,$c,$d){
  

  if(empty($a) ||  empty($b) || !is_numeric($c) || !is_numeric($d)){
  

  return $b;
  

  }
  

  $tmp1=strpos($a,'/',$c+1);
  

  $tmp2=strpos($b,'/',$d+1);
  

  $tmp3=substr($a,$c+1,$tmp1-$c-1);
  

  $tmp4=substr($b,$d+1,$tmp2-$d-1);
  

  if($tmp1!==false&&$tmp2!==false){
  

  if($tmp3===$tmp4){
  

  if($d==0){
  

  $b='..'.substr($b,$tmp2);
  

  }else{
  

  $b=substr($b,0,$d+1).'..'.substr($b,$tmp2);
  

  $tmp2=$tmp2+(2-strlen($tmp4));
  

  }
  

  $b=abc($a,$b,$tmp1,$tmp2);
  

  

  }
  

  }
  

  return $b;
  

  }