require_once被忽略了

Question

strange problem with php on windows... my application loads a 'core' file that loads a settings file, registers autoloads, does initialization etc. at the top of the core file I have include_once("config.php"); this works fine for anything in the current directory, if I include the core file from a separate directory though it just silently ignores the include of the config file... has anyone seen this before?

/webroot/core.php

<?php
  require_once "config.php";
  //register autoloads
  //do some initialization... standard stuff
?>

/webroot/config.php

<?php
  define("WEB_ROOT","/webroot");
  define("DB_USER","root");
  // ... more stuff...
?>

/webroot/admin/index.php

<?php
  require_once("../dbconnect.php");
  echo WEB_ROOT;
  // print string literal WEB_ROOT rather than value in config.php
?>

My understanding is that file operations are relative to the directory of the file making the request, shouldn't the require_once("config.php") select the file relative to core.php? This code works just as I'd expect on a mac or Linux but not at all on windows, (if I change the require to use the full path or ../, it works)

The real madness is that the require_once("config.php") doesn't throw any errors but none of the code inside is executed!

Answer 1

If PHP silently ignore errors, try to put at the top of file that is requested:

ini_set('display_errors', 'On');
error_reporting(E_ALL);

Now all errors should be visible.

Then the best practice (according to me) is to in file that is requested (not in any of included files) define some constant with full filesystem path for application root. So in index.php if application root is /webroot/admin:

define('APP_DIR', dirname(__FILE__));

After that when you include something, use this constant. If the directory structure is:

/webroot/
    admin/
        index.php
    config.php
    core.php

And you want to include config.php into index.php:

require_once APP_DIR . '/../config.php';

In core.php to include config.php it would be:

require_once APP_DIR . '/../config.php';

And so on.

Using absolute filesystem paths will prevent any ambiguities.