21段救命PHP代码

1. 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 - 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生成一个随机字符串
　　如果不需要可阅读的字符串，使用此函数替代，即可创建一个随机字符串，作为用户的随机密码等。
2. PHP生成一个随机字符串

    如果不需要可阅读的字符串，使用此函数替代，即可创建一个随机字符串，作为用户的随机密码等。

        /*************
        *@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编码电子邮件地址
　　使用此代码，可以将任何电子邮件地址编码为 html 字符实体，以防止被垃圾邮件程序收集。
        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, $test_mx = false)
        {
                if(eregi("^([_a-z0-9-]+)(\.[_a-z0-9-]+)*@([a-z0-9-]+)(\.[a-z0-9-]+)*(\.[a-z]{2,4})$", $email))
                        if($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))
                        {
                                while(($file = readdir($handle)) !== false)
                                {
                                        if($file != "." && $file != ".." && $file != "Thumbs.db")
                                        {
                                                echo ''.$file.'
'."\n";
                                        }
                                }
                                closedir($handle);
                        }
                }
        }

6. PHP销毁目录
　　删除一个目录，包括它的内容。
        /*****
        *@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解析 JSON 数据
　　与大多数流行的 Web 服务如 twitter 通过开放 API 来提供数据一样，它总是能够知道如何解析 API 数据的各种传送格式，包括 JSON，XML 等等。
$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解析 XML 数据
        //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 'www.[-a-zA-Z0-9@:%_+.~#?&//=]+)',
        '\1\2'">http://\2">\2', $text);
        $text = eregi_replace('([_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,3})',
        '\1'">mailto:\1">\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 $im2;
        }
　21. PHP检测 ajax 请求
　　大多数的 JavaScript 框架如 jquery，Mootools 等，在发出 Ajax 请求时，都会发送额外的 HTTP_X_REQUESTED_WITH 头部信息，头当他们一个ajax请求，因此你可以在服务器端侦测到 Ajax 请求。
        if(!emptyempty($_SERVER['HTTP_X_REQUESTED_WITH']) && strtolower($_SERVER['HTTP_X_REQUESTED_WITH']) == 'xmlhttprequest'){
                //If AJAX Request Then
        }else{
        //something else
        }