Select random files out of a directory

[howa]

for example, there are 10K files in the directory,

given that i don't know if files name, is it possible to fetch a file
randomly?

thanks.

[Stefan Rybacki]

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Curtis schrieb:

$dir = './';
$files = array();
$file = '';
if ( is_dir($dir) ) {
if ( $d = opendir($dir) ) {
while ( ($file = readdir($d)) !== false ) {
if ( !is_dir($file) ) $files[] = $file;
}
}
}

// specify an int for the optional 2nd arg if you
// need more than one random file
$randomKeys = array_rand($fil es);
$randomFile = $files[$randomKeys[0]];

Without the memory overhead selecting one random file could in addition
look like this then:

$dir = './';
$file = '';
mt_srand(time() );
$probability=mt _getrandmax()/10000;
if ( is_dir($dir) ) {
if ( $d = opendir($dir) ) {
while ( ($file = readdir($d)) !== false ) {
if ( !is_dir($file) ) {
if (mt_rand()<$pro bability) break;
}
}
}
}

I know it's far from perfect and it's not equally distributed but might
save some execution time if you accidently select the second file ;) as
well as you don't have the memory overhead and it takes at most as long
as the original script. Important here is the probability variable,
which should be adjusted with an estimated file count of the desired folder.

Stefan
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