转载的, 用着方便!

1. 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
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. 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。
function generate_rand($len){
    $c= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
    srand((double)microtime()*1000000);
    for($i=0; $i<$len; $i++) {
        $rand.= $c[rand()%strlen($c)];
    }
    return $rand;
}
 
 function rand_password( $length = 8 ) {  
    // 密码字符集，可任意添加你需要的字符  
    $chars = ‘abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789!@#$%^&*()-_ []{}<>~`+=,.;:/?|’;  
    $password = ”;  
    for ( $i = 0; $i < $length; $i++ )  
    {  
        // 这里提供两种字符获取方式  
        // 第一种是使用 substr 截取$chars中的任意一位字符；  
        // 第二种是取字符数组 $chars 的任意元素  
        // $password .= substr($chars, mt_rand(0, strlen($chars) – 1), 1);  
        $password .= $chars[ mt_rand(0, strlen($chars) - 1) ];  
    }  
    return $password;  
} 
 
 
 3. 编码电子邮件地址
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 = ‘<a href="http://www.mamicode.com/ma‘;" ‘. $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. 验证邮件地址
    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. 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 != ".." && $file != "Thumbs.db")
                    {
                        echo ‘<a target="_blank" href="http://www.mamicode.com/‘.$dir.$file.‘">‘.$file.‘</a><br>‘."\n";
                    }
                }
                closedir($handle);
            }
        }
    }
    
    -----------------------------
    function list_dir($path){
        $dp = dir($path);
        while( $fp = $dp->read() ){
            if ( $fp==‘.‘ ){
                }
        }
    }
    -----------------------------
    
   
   
7. 解析 JSON 数据
    $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
    $ary = json_decode($json_string,true);
    echo $ary[‘id‘];
    
    

10. 获取客户端真实 IP 地址
    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. 强制性文件下载   
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. 创建标签云
function getCloud($data = http://www.mamicode.com/array(), $minFontSize = 12, $maxFontSize = 30){"font-size: ‘ . floor($size) . ‘px‘
         . ‘" href="http://www.mamicode.com/#" 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. 寻找两个字符串的相似性
similar_text(‘abcde‘, ‘abcdef‘, $percent);

echo $percent;

16. 文件 Zip 压缩
function create_zip($files = array(), $destination = ‘‘, $overwrite = false){
    if(file_exists($destination) && !$overwrite){
        return false;
    }
    $valid_files = array();
    if(is_array($files)){
        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);
    }else{
        return false;
    }
}
/**
 * **** Example Usage **
 */
$files = array(‘question_20120828_211308.csv‘, ‘question_20120828_211326.csv‘);
create_zip($files, ‘myzipfile.zip‘, true);


17. 解压缩 Zip 文件

function unzip_file($file, $destination){
    $zip = new ZipArchive() ;
    if ($zip->open($file) !== TRUE) {
        die (‘Could not open archive‘);
    }
    $zip->extractTo($destination);    
    $zip->close();
}


20. 调整图像尺寸
$imgsrc = "http://www.nowamagic.net/images/3.jpg";
$width = 780;
$height = 420;

resizejpg($imgsrc, $imgdst, $width, $height);

function resizejpg($imgsrc, $imgdst, $imgwidth, $imgheight){ 
    // $imgsrc jpg格式图像路径 $imgdst jpg格式图像保存文件名 $imgwidth要改变的宽度 $imgheight要改变的高度
    // 取得图片的宽度,高度值
    $arr = getimagesize($imgsrc);
    header("Content-type: image/jpg");

    $imgWidth = $imgwidth;
    $imgHeight = $imgheight; 
    // Create image and define colors
    $imgsrc = http://www.mamicode.com/imagecreatefromjpeg($imgsrc);"‘. str_replace(array("\r", "\n", "<", ">", "&"),  
                    array(‘\r‘, ‘\n‘, ‘\x3c‘, ‘\x3e‘, ‘\x26‘),  
                    addslashes($var)) .‘"‘;  
            case ‘array‘:  
                if (empty($var) || array_keys($var) === range(0, sizeof($var) - 1)) {  
                    $output = array();  
                    foreach ($var as $v) {  
                        $output[] = jsonEncode($v);  
                    }  
                    return ‘[ ‘. implode(‘, ‘, $output) .‘ ]‘;  
                }  
            case ‘object‘:  
                $output = array();  
                foreach ($var as $k => $v) {  
                    $output[] = jsonEncode(strval($k)) .‘: ‘. jsonEncode($v);  
                }  
                return ‘{ ‘. implode(‘, ‘, $output) .‘ }‘;  
            default:  
                return ‘null‘;  
        }    
}

22. 删除目录及其下所有文件
//Delete folder function
function deleteDirectory($dir) {
    if (!file_exists($dir)) return true;
    if (!is_dir($dir) || is_link($dir)) return unlink($dir);
    foreach (scandir($dir) as $item) {
        if ($item == ‘.‘ || $item == ‘..‘) continue;
        if (!deleteDirectory($dir . "/" . $item)) {
            chmod($dir . "/" . $item, 0777);
            if (!deleteDirectory($dir . "/" . $item)) return false;
        };
    }
    return rmdir($dir);
}