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Functions of php_PHP tutorial

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Release: 2016-07-13 17:49:06
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1. PHP can read random strings

This code will create a readable string that is closer to the word in the dictionary, practical, and has password verification capabilities.

/************** 
    *@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 do not need a readable string, use this function instead to create a random string as the user's random password, etc.

/************* 
    *@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 encoded email address

Using this code, any email address can be encoded as an html character entity to prevent it from being collected by spam programs.

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 = '';
          $part4 = '
';                                                       
          $encoded = '';                                                           
          return $encoded;                                      }  





4. PHP verification email address

Email verification is perhaps the most commonly used web form verification in China. In addition to verifying the email address, this code can also choose to check the MX record in the DNS to which the email domain belongs, making the email verification function 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}){1}quot;, $email))
If($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 != ".." && $file != "Thumbs.db")
                                                                                             echo ''.$file.'
'."n";
                                                                                                                                                                                                                                                                        closedir($handle);
                                                                                                                                                   }  





6. PHP destroy directory

Delete a directory, including its contents.

/***** 
    *@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.$file);  
                                                                                                       else                                                                                                                                                                                                                                                                                                                                                              through                                                                                                                                                                                                                      closedir($handle);
               rmdir($dir);                                            return true;                                                                                              else  
                                                                                                       return false;                                                                                     }  





7. PHP parses JSON data

As most popular web services such as twitter provide data through open APIs, it always knows how to parse API data in various delivery formats, including JSON, XML, etc.

$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="


    Foo  
    foo@bar.com  
   
  
      
    Foobar  
    foobar@foo.com  
   
  
   
";   
      
    //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, '
';  
    }  
 
  
 
  
 
  9. PHP创建日志缩略名 
 
  创建用户友好的日志缩略名。 
 
    function create_slug($string){  
    $slug=preg_replace('/[^A-Za-z0-9-]+/', '-', $string);  
    return $slug;  
    }  
 
  
 
  
 
  10. PHP获取客户端真实 IP 地址 
 
  该函数将获取用户的真实 IP 地址,即便他使用代理服务器。 
 
    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强制性文件下载 
 
  为用户提供强制性的文件下载功能。 
 
    /******************** 
    *@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创建标签云 
 
    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[] = ''  
    . htmlspecialchars( stripslashes( $tag ) ) . '
';  
    }   
      
    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寻找两个字符串的相似性 
 
  PHP 提供了一个极少使用的 similar_text 函数,但此函数非常有用,用于比较两个字符串并返回相似程度的百分比。 
 
    similar_text($string1, $string2, $percent);  
    //$percent will have the percentage of similarity   
 
  
 
  
 
  14. PHP在应用程序中使用 Gravatar 通用头像 
 
  随着 WordPress 越来越普及,Gravatar 也随之流行。由于 Gravatar 提供了易于使用的 API,将其纳入应用程序也变得十分方便。 
 
    /****************** 
    *@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, $rating)  
    {  
    echo '     height="'.$size.'px" />';  
    }  
 
  
 
  
 
  15. PHP在字符断点处截断文字 
 
  所谓断字 (word break),即一个单词可在转行时断开的地方。这一函数将在断字处截断字符串。 
 
    // 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文件 Zip 压缩 
 
    /* 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解压缩 Zip 文件 
 
    /********************** 
    *@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 defaults http string for URL address



Sometimes it is necessary to accept URL input in some forms, but users rarely add the http:// field. This code will add that field to the URL.

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







19. PHP converts URL string into 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@:%_+.~#?&//=]+)',
'1', $text);
$text = eregi_replace('([[:space:]()[{}])(www.[-a-zA-Z0-9@:%_+.~#?&//=]+)',
'12', $text);
$text = eregi_replace('([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3})',
'1', $text);
         
Return $text;
}  





20. PHP adjust image size

Creating image thumbnails takes a lot of time, this code will help to understand the logic of 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;                                      }  
1. PHP can read random strings

This code will create a readable string that is closer to the word in the dictionary, practical and has password verification capabilities.

/**************

    *@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 to create a random string as the user’s random password, etc.

/*************

    *@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 encoded email address

Using this code, any email address can be encoded as an html character entity to prevent it from being collected by spam programs.

    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 = '';
        $part4 = '
';  
    
        $encoded = '';  
    
        return $encoded;
    }

 

 

  4. PHP验证邮件地址

  电子邮件验证也许是中最常用的网页表单验证,此代码除了验证电子邮件地址,也可以选择检查邮件域所属 DNS 中的 MX 记录,使邮件验证功能更加强大。

    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}){1}quot;, $email))
            if($test_mx)
            {
                list($username, $domain) = split("@", $email);
                return getmxrr($domain, $mxrecords);
            }
            else
                return true;
        else
            return false;
    }

 

 

  5. PHP列出目录内容

function list_files($dir)
{
          if(is_dir($dir))
           {
If($handle = opendir($dir))
                {
                                                                                                                                                                                                                                                                                                  .                                                  {
If($file != "." && $file != ".." && $file != "Thumbs.db")
                                                               {
echo ''.$file.'
'."n";
                 }
                }
                 closedir($handle);
            }
}
}

6. PHP destroy directory

Delete a directory, including its contents.

/*****

    *@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.$file);
                }
Else                                                  {
                                                                                                                                                                                                                                                                                                          Since                 }
            }
             closedir($handle);
              rmdir($dir);
             return true;
}
        else
           {
              return false;
}
}


 7. PHP parsing JSON data

Like most popular web services such as twitter that provide data through open APIs, it always knows how to parse various delivery formats of API data, including JSON, XML, etc.

$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="


Foo
foo@bar.com


Foobar
foobar@foo.com

";
 
//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, '
';
}

9. PHP creates log abbreviation

Create user-friendly log abbreviations.

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

 10. PHP obtains the real IP address of the client

 This function will get the user’s real IP address, even if he uses 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 mandatory file download

Provide users with mandatory file download function.

/********************
    *@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. Create tag cloud with PHP

    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[] = ''
    . htmlspecialchars( stripslashes( $tag ) ) . '
';
    } 
    
    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寻找两个字符串的相似性

  PHP 提供了一个极少使用的 similar_text 函数,但此函数非常有用,用于比较两个字符串并返回相似程度的百分比。

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

 

 

  14. PHP在应用程序中使用 Gravatar 通用头像

  随着 WordPress 越来越普及,Gravatar 也随之流行。由于 Gravatar 提供了易于使用的 API,将其纳入应用程序也变得十分方便。

    /******************
    *@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, $rating)
    {
    echo '     height="'.$size.'px" />';
    }

 

 

  15. PHP在字符断点处截断文字

  所谓断字 (word break),即一个单词可在转行时断开的地方。这一函数将在断字处截断字符串。

    // 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文件 Zip 压缩

    /* 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解压缩 Zip 文件

    /**********************
    *@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为 URL 地址预设 http 字符串

 

  有时需要接受一些表单中的网址输入,但用户很少添加 http:// 字段,此代码将为网址添加该字段。

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

 

 

 

  19. PHP将网址字符串转换成超级链接

  该函数将 URL 和 E-mail 地址字符串转换为可点击的超级链接。

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

 

 

  20. PHP调整图像尺寸

  创建图像缩略图需要许多时间,此代码将有助于了解缩略图的逻辑。

    /**********************
    *@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;
    }

 

摘自 chaojie2009的专栏

www.bkjia.comtruehttp://www.bkjia.com/PHPjc/478374.htmlTechArticle1. PHP可阅读随机字符串 此代码将创建一个可阅读的字符串,使其更接近词典中的单词,实用且具有密码验证功能。 /************** *@length - l...
source:php.cn
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