Common PHP Functions and Code Snippets

1. Readable random string – Generates a pronounceable random string by alternating consonants and vowels.

function readable_random_string($length = 6){
    $conso=array("b","c","d","f","g","h","j","k","l","m","n","p","r","s","t","v","w","x","y","z");
    $vocal=array("a","e","i","o","u");
    $password="";
    srand((double)microtime()*1000000);
    $max = $length/2;
    for($i=1;$i<=$max;$i++){
        $password .= $conso[rand(0,19)];
        $password .= $vocal[rand(0,4)];
    }
    return $password;
}

2. Simple random string – Creates a generic random string useful for passwords.

function generate_rand($l){
    $c="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    srand((double)microtime()*1000000);
    for($i=0;$i<$l;$i++){
        $rand .= $c[rand()%strlen($c)];
    }
    return $rand;
}

3. Email address encoder – Obfuscates an email address using HTML character entities to deter spam bots.

function encode_email($email='[email protected]', $linkText='Contact Us', $attrs='class="emailencoder"'){
    $email = str_replace('@','@',$email);
    $email = str_replace('.','.', $email);
    $email = str_split($email,5);
    $linkText = str_replace('@','@',$linkText);
    $linkText = str_replace('.','.', $linkText);
    $linkText = str_split($linkText,5);
    $part1 = '<a href="mailto:';
    $part2 = '';
    $part3 = '" '.$attrs.'>';
    $part4 = '</a>';
    $encoded = '<script type="text/javascript">';
    $encoded .= "document.write('$part1');";
    foreach($email as $e){ $encoded .= "document.write('$e');"; }
    $encoded .= "document.write('$part3');";
    foreach($linkText as $l){ $encoded .= "document.write('$l');"; }
    $encoded .= "document.write('$part4');";
    $encoded .= '</script>';
    return $encoded;
}

4. Email validator – Checks email format and optionally verifies MX records.

function is_valid_email($email, $test_mx = false){
    if(eregi("^([_a-z0-9-]+)(\.[_a-z0-9-]+)*@([a-z0-9-]+)(\.[a-z0-9-]+)*(\.[a-z]{2,4})$", $email)){
        if($test_mx){
            list($username,$domain) = split("@", $email);
            return getmxrr($domain, $mxrecords);
        }
        return true;
    }
    return false;
}

5. List directory contents – Outputs links for each file in a directory, skipping '.' and '..'.

function list_files($dir){
    if(is_dir($dir) && ($handle = opendir($dir))){
        while(($file = readdir($handle)) !== false){
            if($file != "." && $file != ".." && $file != "Thumbs.db"){
                echo '<a target="_blank" href="'.$dir.$file.'">'.$file.'</a><br>\n';
            }
        }
        closedir($handle);
    }
}

6. Destroy directory – Recursively deletes a directory and all its contents.

function destroyDir($dir, $virtual = false){
    $ds = DIRECTORY_SEPARATOR;
    $dir = $virtual ? realpath($dir) : $dir;
    $dir = substr($dir,-1) == $ds ? substr($dir,0,-1) : $dir;
    if(is_dir($dir) && $handle = opendir($dir)){
        while($file = readdir($handle)){
            if($file == '.' || $file == '..') continue;
            if(is_dir($dir.$ds.$file)) destroyDir($dir.$ds.$file);
            else unlink($dir.$ds.$file);
        }
        closedir($handle);
        rmdir($dir);
        return true;
    }
    return false;
}

7. JSON parsing – Decodes a JSON string into an object and accesses its properties.

$json_string='{"id":1,"name":"foo","email":"[email protected]","interest":["wordpress","php"]}';
$obj = json_decode($json_string);
echo $obj->name; // prints foo
echo $obj->interest[1]; // prints php

8. XML parsing – Loads an XML string with SimpleXML and iterates over user nodes.

$xml_string = "<?xml version='1.0'?><users><user id='398'><name>Foo</name><email>[email protected]</email></user><user id='867'><name>Foobar</name><email>[email protected]</email></user></users>";
$xml = simplexml_load_string($xml_string);
foreach($xml->user as $user){
    echo $user['id'], ' ';
    echo $user->name, ' ';
    echo $user->email, "<br>";
}

9. Slug creator – Generates a URL‑friendly slug from a string.

function create_slug($string){
    $slug = preg_replace('/[^A-Za-z0-9-]+/', '-', $string);
    return $slug;
}

10. Real IP address – Retrieves the client’s true IP even behind proxies.

function getRealIpAddr(){
    if(!empty($_SERVER['HTTP_CLIENT_IP'])) $ip = $_SERVER['HTTP_CLIENT_IP'];
    elseif(!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    else $ip = $_SERVER['REMOTE_ADDR'];
    return $ip;
}

11. Forced file download – Sends appropriate headers to force a file download.

function force_download($file){
    if(isset($file) && file_exists($file)){
        header('Content-length: '.filesize($file));
        header('Content-Type: application/octet-stream');
        header('Content-Disposition: attachment; filename="'.$file.'"');
        readfile($file);
    } else {
        echo 'No file selected';
    }
}

12. Tag cloud generator – Builds an HTML tag cloud with font sizes scaled to tag frequency.

function getCloud($data=array(), $minFontSize=12, $maxFontSize=30){
    $minimumCount = min(array_values($data));
    $maximumCount = max(array_values($data));
    $spread = $maximumCount - $minimumCount;
    $spread == 0 && $spread = 1;
    $cloudTags = array();
    foreach($data as $tag=>$count){
        $size = $minFontSize + ($count-$minimumCount) * ($maxFontSize-$minFontSize) / $spread;
        $cloudTags[] = '<a style="font-size:'.floor($size).'px" href="#" title="'.$tag.' returned a count of '.$count.'">'.htmlspecialchars(stripslashes($tag)).'</a>';
    }
    return implode("\n", $cloudTags)."\n";
}

13. String similarity – Uses similar_text to compute percentage similarity between two strings.

similar_text($string1, $string2, $percent); // $percent holds similarity percentage

14. Gravatar display – Generates an <img> tag for a Gravatar based on an email address.

function show_gravatar($email, $size, $default, $rating){
    echo '<img src="http://www.gravatar.com/avatar.php?gravatar_id='.md5($email).'&amp;default='.$default.'&amp;size='.$size.'&amp;rating='.$rating.'" width="'.$size.'px" height="'.$size.'px" />';
}

15. Word‑break truncation – Truncates a string at a specified breakpoint and appends an ellipsis.

function myTruncate($string, $limit, $break=".", $pad="..."){
    if(strlen($string) <= $limit) return $string;
    if(($breakpoint = strpos($string, $break, $limit)) !== false && $breakpoint < strlen($string)-1){
        $string = substr($string, 0, $breakpoint) . $pad;
    }
    return $string;
}

16. ZIP archive creation – Compresses an array of files into a ZIP archive.

function create_zip($files=array(), $destination='', $overwrite=false){
    if(file_exists($destination) && !$overwrite) return false;
    $valid_files = array();
    foreach($files as $file){ if(file_exists($file)) $valid_files[] = $file; }
    if(count($valid_files)){
        $zip = new ZipArchive();
        if($zip->open($destination, $overwrite ? ZipArchive::OVERWRITE : ZipArchive::CREATE) !== true) return false;
        foreach($valid_files as $file) $zip->addFile($file, $file);
        $zip->close();
        return file_exists($destination);
    }
    return false;
}

17. ZIP extraction – Extracts a ZIP file to a specified directory.

function unzip_file($file, $destination){
    $zip = new ZipArchive();
    if($zip->open($file) !== TRUE) die('Could not open archive');
    $zip->extractTo($destination);
    $zip->close();
    echo 'Archive extracted to directory';
}

18. Prepend http to URLs – Ensures a URL starts with http:// or ftp:// .

if(!preg_match('/^(http|ftp):/', $_POST['url'])){
    $_POST['url'] = 'http://'.$_POST['url'];
}

19. Clickable link conversion – Converts plain URLs and email addresses in text into HTML links.

function makeClickableLinks($text){
    $text = eregi_replace('(((f|ht){1}tp://)[-a-zA-Z0-9@:%_+.~#?&amp;//=]+)', '<a href="\1">\1</a>', $text);
    $text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_+.~#?&amp;//=]+)', '\1<a href="http://\2">\2</a>', $text);
    $text = eregi_replace('([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3})', '<a href="mailto:\1">\1</a>', $text);
    return $text;
}

20. Image resizing – Resizes an image while preserving aspect ratio.

function resize_image($filename, $tmpname, $xmax, $ymax){
    $ext = pathinfo($filename, PATHINFO_EXTENSION);
    if($ext == 'jpg' || $ext == 'jpeg') $im = imagecreatefromjpeg($tmpname);
    elseif($ext == 'png') $im = imagecreatefrompng($tmpname);
    elseif($ext == 'gif') $im = imagecreatefromgif($tmpname);
    $x = imagesx($im);
    $y = imagesy($im);
    if($x <= $xmax && $y <= $ymax) return $im;
    if($x >= $y){ $newx = $xmax; $newy = $newx * $y / $x; }
    else { $newy = $ymax; $newx = $x * $ymax / $y; }
    $im2 = imagecreatetruecolor($newx, $newy);
    imagecopyresized($im2, $im, 0,0,0,0, floor($newx), floor($newy), $x, $y);
    return $im2;
}

21. AJAX request detection – Determines whether the current request was made via AJAX.

if(!empty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest'){
    // AJAX request handling
} else {
    // regular request handling
}