PHP面试题之[求相对路径]

题目：写一个函数，算出两个文件的相对路径如 $a = '/a/b/c/d/e.php'; $b = '/a/b/12/34/c.php'; 计算出 $b 相对于 $a 的相对路径应该是 ../../c/d

答：

 

<?php



function getRelative($a , $b)

{

$arr_a = explode("/" , $a) ;

$brr_b = explode("/" , $b) ;

$i = 1 ;

while (true) {

     if($arr_a[$i] == $brr_b[$i]) {

        $i ++ ;

     } else {

         break ;

    }

}

$c = count($brr_b) ;

$d = count($arr_a) ;

$e = ($c>$d)?$c:$d ;

$str1 = '' ;

$str2 = '' ;

for ($j = $i ;$j<$e ;$j++) {

   if(isset($arr_a[$j])) {

    if($j<($d-1)){

     $str1 .= $arr_a[$j] . "/" ;

    } else {

     $str1 .= $arr_a[$j] ;

    }


   }

   if(isset($brr_b[$j])) {

    $str2 .= "../" ;

   }

}

return $str2 . $str1 ;

}



$a = "/c/b/c/d/k/h/t/e.php" ;

$b = "/a/b/e/f/h.php" ;

$relative = getRelative($a,$b) ;

var_dump($relative);

?>

运行结果：string(34) "../../../../../c/b/c/d/k/h/t/e.php"

end up