PHP dirname（__ FILE__）v / s ./ [重复]

Question

This question already has an answer here:

• What's better of require(dirname(__FILE__).'/'.'myParent.php') than just require('myParent.php')? 4 answers

I found this code in a small script I'm modifying for my own use:

require dirname(__FILE__)."/GearmanManager.php";

I found it to be a bit strange, wouldn't

require "./GearmanManager.php";

do the exact same thing?

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Answer 1

When you use ./ you're looking in the current working directory which might change. dirname(__FILE__) on the other hand won't change.

If you for instance change the working directory (using chdir('/') or similar) before the require, your first example will succeed whereas your second will fail.

Excerpt from another answer:

However, it is more efficient to explicitly use include './file' than having PHP always check the current directory for every include.

So if you know you're not going to be changing directory, ./ will be faster.