<?php

//计算出两个文件的相对路径即path2相对于$path1的相对路径

// http://www.manongjc.com/article/1342.html

function get_relative_path($path1,$path2){

    $arr1 = explode(DIRECTORY_SEPARATOR,dirname($path1));

    $arr2 = explode(DIRECTORY_SEPARATOR,dirname($path2));

    $length = count($arr2);

    for($i = 0; $i < $length; $i++){

        if($arr1[$i] != $arr2[$i]){ //进行路径匹配

            break;

        }

    }

    if($i == 0){                    //根目录不同

        return '不在同一个目录中';

    }else if($i != 0 && $i < $length){        //在同一个个目录下

        $separator = array_fill(0, ($length-$i), '..');

        return(implode(DIRECTORY_SEPARATOR, array_merge($separator, array_slice($arr1, $i))));

    }else if($i == $length){                //路径完全相同 http://www.manongjc.com/article/1343.html

        return '.';

    }

}

$path1 = 'F:\Apache\www\temp\php_demo\demo.md'; //参照路径path1

$path2 = 'F:\Apache\www\temp\php_demo\demo.md';

$path3 = 'F:\Apache\www\temp\sd\ss.d\sdsfd';

$path4 = 'G:\FFOutput';

var_dump(get_relative_path($path1,$path2));

var_dump(get_relative_path($path1,$path3));

var_dump(get_relative_path($path1,$path4));

?>