How to calculate the relative path of a file in php

This article mainly introduces the method of PHP calculating the relative path of two files, involving the skills of PHP operating strings, and has certain reference value. Friends in need can refer to it

The examples in this article describe PHP Method to calculate the relative paths of two files. Share it with everyone for your reference. The details are as follows:

1. Question:

Write a php function to calculate the relative paths of two files. For example, $a="/a/b/c/d/e.php"; $b="/a/b/12/34/c.php", what is the relative path of B relative to A?

2. Solution:

<?php
/**
 * 求$b相对于$a的相对路径
 * @param string $a
 * @param string $b
 * @return string
 */
function getRelativePath ($a, $b)
{
  $patha = explode(&#39;/&#39;, $a);
  $pathb = explode(&#39;/&#39;, $b);
  $counta = count($patha) - 1;
  $countb = count($pathb) - 1;
  $path = "../";
  if ($countb > $counta) {
    while ($countb > $counta) {
      $path .= "../";
      $countb --;
    }
  }
  // 寻找第一个公共结点
  for ($i = $countb - 1; $i >= 0;) {
    if ($patha[$i] != $pathb[$i]) {
      $path .= "../";
      $i --;
    } else {
//判断是否为真正的第一个公共结点，防止出现子目录重名情况
      for ($j = $i - 1, $flag = 1; $j >= 0; $j --) {
        if ($patha[$j] == $pathb[$j]) {
          continue;
        } else {
          $flag = 0;
          break;
        }
      }
      if ($flag)
        break;
      else
        $i ++;
    }
  }
  for ($i += 1; $i <= $counta; $i ++) {
    $path .= $patha[$i] . "/";
  }
  return $path;
}
$a = "/a/c/d/e.php";
$b = "/a/c.php";
$path = getRelativePath($a, $b);
echo $path;

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