Randomness... on PHP

[Kitsune Devil]

Hello,
Suppose I want a PHP code which allows me to show a random image (with a link that corresponds with the image) on my page. I have the images stored in a folder... now what do I do? I'm quite new at this...
~Kitsune

[keith]

first thing's first... you'll need some type of database that stores the image names with a corresponding link.

[bloodyveins]

the solution could be either listing all files in that directory (using php functions: opendir, readdir, is_file) and then generating seed to choose random image or listing all files manually in a flat file and then choosing a random image from it.

i think, there is no need of database. this process can be done automatically.

[Kitsune Devil]

Ah, I see. Thanks!!

[keith]

Originally posted by bloodyveins
the solution could be either listing all files in that directory (using php functions: opendir, readdir, is_file) and then generating seed to choose random image or listing all files manually in a flat file and then choosing a random image from it.

i think, there is no need of database. this process can be done automatically.

well, that's what i was getting at. as far as i'm concerned, even a single file storing info is a type of database.

you could even store them in the actual php file, which is about as rudementary of a database as you could get:

<?php

$rand = rand(1,5);

switch ($rand) {
case 1:
  echo "<a href=\"http://www.domain.com\"><img src=\"domain.jpg\"></a>";
  break;
case 2:
  echo "<a href=\"http://www.something.com\"><img src=\"something.jpg\"></a>";
  break;
case 3:
  echo "<a href=\"http://www.another.com\"><img src=\"another.jpg\"></a>";
  break;
case 4:
  echo "<a href=\"http://whatever.com\"><img src=\"whatever.jpg\"></a>";
  break;
case 5:
  echo "<a href=\"http://slappystick.com\"><img src=\"slappystick.jpg\"></a>";
  break;
}

?>

[bloodyveins]

err... i think i misdelivered my idea keith.
what i meant by listing all files manually in a flat file and then choosing a random image from it. should be listing all images files in a flat file through such mechanism and then choosing a random image from it.
The function of flat file here is as "cache". The existence of flat file will reduce time wasting while reading directory and generating seed. This process could be called automatic, since you don't write all filenames by yourself. You may also involve cron job to update the image file list in the file.

Here is an example code of how it works:

//Set up variables
$imgDir = "myImage/"; //relative to current file
$imgListFile = "imglist.txt";

function fileExtension ($givenFile) {
    $arrayFile = explode(".",$givenFile);
    $ext = count($arrayFile) - 1;
    return $arrayFile[$ext];
}

function file_list($dir) {
    global $imgListFile;
    if (is_dir($dir)) {
        $fd = @opendir($dir);
        while (($part = @readdir($fd)) == true) {            
            if ($part != "." && $part != "..") {
                if(is_file($dir.$part)) {
                    if (fileExtension($part) == "jpg" || fileExtension($part) == "jpeg" || fileExtension($part) == "gif" || fileExtension($part) == "png") {
                        $file_array[] = $part;
                    }
                }
            }
            clearstatcache();
        }
        if ($fd == true) {
            closedir($fd);
        }
        if (is_array($file_array)) {
            natsort($file_array);
            $fp = fopen($imgListFile,'wb');
            if(is_writable($imgListFile) && flock($fp,LOCK_EX)) {
                for($i=0;$i<count($file_array); $i++)
                    $content .= $file_array[$i].";";
                $content = preg_replace("/;$/","\n",$content);
                fwrite($fp,$content);
                flock($fp,LOCK_UN);
                fclose($fp);
            }    
            return $file_array;
        } 
        else {
            return false;
        }
    }
    else {
        return false;
    }
}

function imgFromFile ($pathToFile) {
    $fp = fopen($pathToFile,'rb');
    if(!$fp) 
        return 0;
    $fileImg = fread($fp,filesize($pathToFile));
    fclose($fp);
    $file_array = explode(";",$fileImg);
    return $file_array;
}

function chooseImg($method = 1) {
    if($method == 1) { //use file_list
        global $imgDir;
        $fileList = file_list($imgDir);

    }
    else { //use imgFromFile
        global $imgListFile;
        $fileList = imgFromFile($imgListFile);
    } 
    $totElement = count($fileList) - 1;
    $chosen = rand(1,$totElement);
    return $fileList[$chosen];
}

//Usage:

$img = chooseImg(1);
print "Image chosen from <b>listing image file</b>: ".$img;

print "<br />";

$img = chooseImg(2);
print "Image chosen from <b>$imgListFile</b>: ".$img; 

This code does run. When I made it, I'd tested it with dummy data. This is a special one for you!! Wish this help..