readdir vs scandir

Question

1] Which of the functions is faster?
2] what are the differences?

Differences

1] readdir returns the name of the next entry in the directory. Scandir returns an array of files and directories from the directory.

2] readdir has to have a resource handle open until all the entries are read. scandir, perhaps creates an array of all the entries and closes the resouce handle?

Answer 1

Just getting the results (without doing anything), readdir is a minimum faster:

<?php  $count = 10000;  $dir = '/home/brati';  $startScan = microtime(true); for ($i=0;$i<$count;$i++) {     $array = scandir($dir); } $endScan = microtime(true);   $startRead = microtime(true); for ($i=0;$i<$count;$i++) {     $handle = opendir($dir);     while (false !== ($entry = readdir($handle))) {         // We do not know what to do     } } $endRead = microtime(true);  echo "scandir: " . ($endScan-$startScan) . "\n"; echo "readdir: " . ($endRead-$startRead) . "\n"; 

Gives:

== RUN 1 == scandir: 5.3707950115204 readdir: 5.006147146225  == RUN 2 == scandir: 5.4619920253754 readdir: 4.9940950870514  == RUN 3 == scandir: 5.5265231132507 readdir: 5.1714680194855 

Then of course it depends on what you intend to do. If you have to write another loop with scandir(), it will be slower.

Answer 2

It really depends what you're doing with the data.

If you're going through entry-by-entry, you should be using readdir, if you actually need to have a list of the entries in memory, you should be using scandir.

There's no sense copying information into memory when you're going to be using it entry-by-entry anyway. Lazy evaluation is definitely the way to go in that case.

I would imagine that scandir is just a wrapper around the same thing that readdir is calling, and would therefore be slower.