PHP阵列阻止列表
问题描述:
I've created this code to cycle through the folders in the current directory and echo out a link to the folder, it all works fine. How would I go about using the $blacklist
array as an array to hold the directory names of directories I dont want to show?
$blacklist = array('dropdown');
$results = array();
$dir = opendir("./");
while($file = readdir($dir)) {
if($file != "." && $file != "..") {
$results[] = $file;
}
}
closedir($dir);
foreach($results as $file) {
if($blocked != true) {
$fileUrl = $file;
$fileExplodedName = explode("_", $file);
$fileName = "";
$fileNameCount = count($fileExplodedName);
echo "<a href='".$fileUrl."'>";
$i = 1;
foreach($fileExplodedName as $name) {
$fileName .= $name." ";
}
echo trim($fileName);
echo "</a><br/>";
}
}
答
Use in_array for this.
$blocked = in_array($file, $blacklist);
Note that this is rather expensive. The runtime complexity of in_array is O(n) so don't make a large blacklist. This is actually faster, but with more "clumsy" code:
$blacklist = array('dropdown' => true);
/* ... */
$blocked = isset($blacklist[$file]);
The runtime complexity of the block check is then reduced to O(1) since the array (hashmap) is constant time on key lookup.
答
array_diff
is the best tool for this job -- it's the shortest to write, very clear to read, and I would expect also the fastest.
$filesToShow = array_diff($results, $blacklist);
foreach($filesToShow as $file) {
// display the file
}