21 Handy and Practical PHP Code Snippets

Author: Paran

1. PHP readable random string

This code creates a readable string that is closer to words found in a dictionary, which is practical and also works for password verification.

/**************
*@length - length of random string (must be a multiple of 2)
**************/
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. PHP generates a random string

If you don’t need a readable string, use this function instead — it creates a random string you can hand out as a user’s random password and so on.

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

3. PHP encodes email addresses

With this code you can encode any email address into HTML character entities to keep it from being harvested by spam bots.

function encode_email($email='info@domain.com', $linkText='Contact Us', $attrs ='class="emailencoder"' )
{
    // remplazar aroba y puntos
    $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="ma';
    $part2 = 'ilto&#58;';
    $part3 = '" '. $attrs .' >';
    $part4 = '</a>';  

    $encoded = '<script type="text/javascript">';
    $encoded .= "document.write('$part1');";
    $encoded .= "document.write('$part2');";
    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. PHP validates an email address

Email validation is probably the most common form of web form validation. Besides validating the email address itself, this code can also optionally check the MX records in the DNS of the mail domain, which makes the email validation even more powerful.

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);
        }
        else
            return true;
    else
        return false;
}

5. PHP lists directory contents

function list_files($dir)
{
    if(is_dir($dir))
    {
        if($handle = opendir($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. PHP destroys a directory

Delete a directory, including everything inside it.

/*****
*@dir - Directory to destroy
*@virtual[optional]- whether a virtual directory
*/
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 == '.' || $file == '..')
            {
                continue;
            }
            elseif (is_dir($dir.$ds.$file))
            {
                destroyDir($dir.$ds.$file);
            }
            else
            {
                unlink($dir.$ds.$file);
            }
        }
        closedir($handle);
        rmdir($dir);
        return true;
    }
    else
    {
        return false;
    }
}

7. PHP parses JSON data

Just as most popular web services such as Twitter expose their data through an open API, it always pays to know how to parse the various transport formats of API data, including JSON, XML and so on.

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

8. PHP parses XML data

//xml string
$xml_string="<?xml version='1.0'?>
<users>
   <user id='398'>
      <name>Foo</name>
      <email>foo@bar.com</name>
   </user>
   <user id='867'>
      <name>Foobar</name>
      <email>foobar@foo.com</name>
   </user>
</users>";  

//load the xml string using simplexml
$xml = simplexml_load_string($xml_string);  

//loop through the each node of user
foreach ($xml->user as $user)
{
   //access attribute
   echo $user['id'], '  ';
   //subnodes are accessed by -> operator
   echo $user->name, '  ';
   echo $user->email, '<br />';
}

9. PHP creates a post slug

Create a user-friendly post slug.

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

10. PHP gets the client’s real IP address

This function gets the user’s real IP address even when they are behind a proxy server.

function getRealIpAddr()
{
    if (!emptyempty($_SERVER['HTTP_CLIENT_IP']))
    {
        $ip=$_SERVER['HTTP_CLIENT_IP'];
    }
    elseif (!emptyempty($_SERVER['HTTP_X_FORWARDED_FOR']))
    //to check ip is pass from proxy
    {
        $ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
    }
    else
    {
        $ip=$_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}

11. PHP forces a file download

Give users a forced file download feature.

/********************
*@file - path to file
*/
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. PHP creates a tag cloud

function getCloud( $data = array(), $minFontSize = 12, $maxFontSize = 30 )
{
    $minimumCount = min( array_values( $data ) );
    $maximumCount = max( array_values( $data ) );
    $spread       = $maximumCount - $minimumCount;
    $cloudHTML    = '';
    $cloudTags    = array();  

    $spread == 0 && $spread = 1;  

    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 join( "\n", $cloudTags ) . "\n";
}
/**************************
****   Sample usage    ***/
$arr = Array('Actionscript' => 35, 'Adobe' => 22, 'Array' => 44, 'Background' => 43,
    'Blur' => 18, 'Canvas' => 33, 'Class' => 15, 'Color Palette' => 11, 'Crop' => 42,
    'Delimiter' => 13, 'Depth' => 34, 'Design' => 8, 'Encode' => 12, 'Encryption' => 30,
    'Extract' => 28, 'Filters' => 42);
echo getCloud($arr, 12, 36);

13. PHP finds the similarity between two strings

PHP ships with a rarely used function called similar_text, but it is very useful — it compares two strings and returns a percentage for how similar they are.

similar_text($string1, $string2, $percent);
//$percent will have the percentage of similarity

14. PHP uses Gravatar universal avatars in your application

As WordPress becomes more and more widespread, Gravatar has grown popular along with it. And since Gravatar offers an easy-to-use API, working it into your application is a breeze.

/******************
*@email - Email address to show gravatar for
*@size - size of gravatar
*@default - URL of default gravatar to use
*@rating - rating of Gravatar(G, PG, R, X)
*/
function show_gravatar($email, $size, $default, $rating)
{
    echo '<img src="http://www.gravatar.com/avatar.php?gravatar_id='.md5($email).
        '&default='.$default.'&size='.$size.'&rating='.$rating.'" width="'.$size.'px"
        height="'.$size.'px" />';
}

15. PHP truncates text at a word break

A word break is a point where a word can be split when the line wraps. This function truncates a string at such a break.

// Original PHP code by Chirp Internet: www.chirp.com.au
// Please acknowledge use of this code by including this header.
function myTruncate($string, $limit, $break=".", $pad="...") {
    // return with no change if string is shorter than $limit
    if(strlen($string) <= $limit)
        return $string;   

    // is $break present between $limit and the end of the string?
    if(false !== ($breakpoint = strpos($string, $break, $limit))) {
        if($breakpoint < strlen($string) - 1) {
            $string = substr($string, 0, $breakpoint) . $pad;
        }
    }
    return $string;
}
/***** Example ****/
$short_string=myTruncate($long_string, 100, ' ');

16. PHP Zip file compression

/* creates a compressed zip file */
function create_zip($files = array(),$destination = '',$overwrite = false) {
    //if the zip file already exists and overwrite is false, return false
    if(file_exists($destination) && !$overwrite) { return false; }
    //vars
    $valid_files = array();
    //if files were passed in...
    if(is_array($files)) {
        //cycle through each file
        foreach($files as $file) {
            //make sure the file exists
            if(file_exists($file)) {
                $valid_files[] = $file;
            }
        }
    }
    //if we have good files...
    if(count($valid_files)) {
        //create the archive
        $zip = new ZipArchive();
        if($zip->open($destination,$overwrite ? ZIPARCHIVE::OVERWRITE : ZIPARCHIVE::CREATE) !== true) {
            return false;
        }
        //add the files
        foreach($valid_files as $file) {
            $zip->addFile($file,$file);
        }
        //debug
        //echo 'The zip archive contains ',$zip->numFiles,' files with a status of ',$zip->status;  

        //close the zip -- done!
        $zip->close();  

        //check to make sure the file exists
        return file_exists($destination);
    }
    else
    {
        return false;
    }
}
/***** Example Usage ***/
$files=array('file1.jpg', 'file2.jpg', 'file3.gif');
create_zip($files, 'myzipfile.zip', true);

17. PHP unzips a Zip file

/**********************
*@file - path to zip file
*@destination - destination directory for unzipped files
*/
function unzip_file($file, $destination){
    // create object
    $zip = new ZipArchive() ;
    // open archive
    if ($zip->open($file) !== TRUE) {
        die (’Could not open archive’);
    }
    // extract contents to destination directory
    $zip->extractTo($destination);
    // close archive
    $zip->close();
    echo 'Archive extracted to directory';
}

18. PHP prepends the http string to a URL address

Sometimes you need to accept a URL entered into a form, but users rarely type the http:// part — this code adds it for them.

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

19. PHP turns a URL string into a hyperlink

This function converts URL and email address strings into clickable hyperlinks.

function makeClickableLinks($text) {
 $text = eregi_replace('(((f|ht){1}tp://)[-a-zA-Z0-9@:%_+.~#?&//=]+)',
 '<a href="\1">\1</a>', $text);
 $text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_+.~#?&//=]+)',
 '\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. PHP resizes an image

Creating image thumbnails takes quite a bit of time, and this code will help you understand the logic behind thumbnails.

/**********************
*@filename - path to the image
*@tmpname - temporary path to thumbnail
*@xmax - max width
*@ymax - max height
*/
function resize_image($filename, $tmpname, $xmax, $ymax)
{
    $ext = explode(".", $filename);
    $ext = $ext[count($ext)-1];  

    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 / $y * $newy;
    }  

    $im2 = imagecreatetruecolor($newx, $newy);
    imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y);
    return $im2;
}

21. PHP detects Ajax requests

Most JavaScript frameworks such as jQuery and Mootools send an extra HTTP_X_REQUESTED_WITH header when they fire off an Ajax request, marking it as an Ajax request, so you can detect Ajax requests on the server side.

if(!emptyempty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest'){
    //If AJAX Request Then
}else{
//something else
}