Traverse PHP array in key order

07 August 2014

Say you’ve got an array with numerical keys (which aren’t continuous), such as file information keyed by file modified time:

//Make an array of all files in the directory './stuff'
$fileArray = [];
foreach(glob('stuff/*') as $file) 
{
	//Get the time it was last updated (int)
	$modified = filemtime($file);

	//Make a file info object
	$fileInfo = [
		"name" => $file,
		"modified" => $modified
	];
	
	//Store it using the 'file modified time' as the key
	$fileArray[$modified] = $fileInfo;
}

If you try to foreach over these, they come out in the order they went into the array, regardless of keys.

To sort the output by key

My way to fix this problem is to get the array of keys, sort that, and then use it to iterate:

//Get the keys and sort them
$keys = array_keys($fileArray);
sort($keys);

//Iterate over the keys, which are now sorted:
foreach($keys as $key)
{
	$thisFile = $fileArray[$key];
	echo $thisFile["modified"] + " - " + $thisFile["name"];
}