10个超级有用值得收藏的PHP代码片段

尽管php经常被人诟病，被人贬低，被人当玩笑开，事实证明，php是全世界网站开发中使用率最高的编程语言。php最大的缺点是太简单，语法不严谨，框架体系很弱，但这也是它最大的优点，一个有点编程背景的普通人，只需要学习php半天时间，就可以上手开始开发web应用了。

网上有人总结几种编程语言的特点，我觉得也挺有道理的：

php 就是： quick and dirty
java 就是： beauty and slowly
ruby 就是： quick and beauty
python 就是： quick and simple

在php的流行普及中，网上总结出了很多实用的php代码片段，这些代码片段在当你遇到类似的问题时，粘贴过去就可以使用，非常的高效，非常的省时省力。将这些程序员前辈总结出的优秀代码放到自己的知识库中，是一个善于学习的程序员的好习惯。

一、黑名单过滤

function is_spam($text, $file, $split = ':', $regex = false){
    $handle = fopen($file, 'rb');
    $contents = fread($handle, filesize($file));
    fclose($handle);
    $lines = explode("n", $contents);
    $arr = array();
    foreach($lines as $line){
        list($word, $count) = explode($split, $line);
        if($regex)
            $arr[$word] = $count;
        else
            $arr[preg_quote($word)] = $count;
    }
    preg_match_all("~".implode('|', array_keys($arr))."~", $text, $matches);
    $temp = array();
    foreach($matches[0] as $match){
        if(!in_array($match, $temp)){
            $temp[$match] = $temp[$match] + 1;
            if($temp[$match] >= $arr[$word])
                return true;
        }
    }
    return false;
}

$file = 'spam.txt';
$str = 'this string has cat, dog word';
if(is_spam($str, $file))
    echo 'this is spam';
else
    echo 'this is not spam';
ab:3
dog:3
cat:2
monkey:2

二、随机颜色生成器

function randomcolor() {
    $str = '#';
    for($i = 0 ; $i < 6 ; $i++) {
        $randnum = rand(0 , 15);
        switch ($randnum) {
            case 10: $randnum = 'a'; break;
            case 11: $randnum = 'b'; break;
            case 12: $randnum = 'c'; break;
            case 13: $randnum = 'd'; break;
            case 14: $randnum = 'e'; break;
            case 15: $randnum = 'f'; break;
        }
        $str .= $randnum;
    }
    return $str;
}
$color = randomcolor();

三、从网络下载文件

set_time_limit(0);
// supports all file types
// url here:
$url = 'http://somsite.com/some_video.flv';
$pi = pathinfo($url);
$ext = $pi['extension'];
$name = $pi['filename'];

// create a new curl resource
$ch = curl_init();

// set url and other appropriate options
curl_setopt($ch, curlopt_url, $url);
curl_setopt($ch, curlopt_header, false);
curl_setopt($ch, curlopt_binarytransfer, true);
curl_setopt($ch, curlopt_autoreferer, true);
curl_setopt($ch, curlopt_followlocation, true);
curl_setopt($ch, curlopt_returntransfer, true);

// grab url and pass it to the browser
$opt = curl_exec($ch);

// close curl resource, and free up system resources
curl_close($ch);

$savefile = $name.'.'.$ext;
if(preg_match("/[^0-9a-z._-]/i", $savefile))
    $savefile = md5(microtime(true)).'.'.$ext;

$handle = fopen($savefile, 'wb');
fwrite($handle, $opt);
fclose($handle);
四、alexa/google page rank

function page_rank($page, $type = 'alexa'){
    switch($type){
        case 'alexa':
            $url = 'http://alexa.com/siteinfo/';
            $handle = fopen($url.$page, 'r');
        break;
        case 'google':
            $url = 'http://google.com/search?client=navclient-auto&ch=6-1484155081&features=rank&q=info:';
            $handle = fopen($url.'http://'.$page, 'r');
        break;
    }
    $content = stream_get_contents($handle);
    fclose($handle);
    $content = preg_replace("~(n|t|ss+)~",'', $content);
    switch($type){
        case 'alexa':
            if(preg_match('~<div class="data (down|up)"><img.+?>(.+?) </div>~im',$content,$matches)){
                return $matches[2];
            }else{
                return false;
            }
        break;
        case 'google':
            $rank = explode(':',$content);
            if($rank[2] != '')
                return $rank[2];
            else
                return false;
        break;
        default:
            return false;
        break;
    }
}
// alexa page rank:
echo 'alexa rank: '.page_rank('techug.com');
echo '
';
// google page rank
echo 'google rank: '.page_rank('techug.com', 'google');

五、强制下载文件

$filename = $_get['file']; //get the fileid from the url
// query the file id
$query = sprintf("select * from tablename where id = '%s'",mysql_real_escape_string($filename));
$sql = mysql_query($query);
if(mysql_num_rows($sql) > 0){
    $row = mysql_fetch_array($sql);
    // set some headers
    header("pragma: public");
    header("expires: 0");
    header("cache-control: must-revalidate, post-check=0, pre-check=0");
    header("content-type: application/force-download");
    header("content-type: application/octet-stream");
    header("content-type: application/download");
    header("content-disposition: attachment; filename=".basename($row['filename']).";");
    header("content-transfer-encoding: binary");
    header("content-length: ".filesize($row['filename']));

    @readfile($row['filename']);
    exit(0);
}else{
    header("location: /");
    exit;
}

六、通过email显示用户的gravatar头像

 $gravatar_link = 'http://www.gravatar.com/avatar/' . md5($comment_author_email) . '?s=32';
  echo '<img src="' . $gravatar_link . '" />';

七、通过curl获取rss订阅数

$ch = curl_init();
curl_setopt($ch,curlopt_url,'https://feedburner.google.com/api/awareness/1.0/getfeeddata?id=7qkrmib4r9rscbplq5qgadiiq4');
curl_setopt($ch,curlopt_returntransfer,1);
curl_setopt($ch,curlopt_connecttimeout,2);
$content = curl_exec($ch);
$subscribers = get_match('/circulation="(.*)"/isu',$content);
curl_close($ch);

八、时间差异计算函数

function ago($time)
{
   $periods = array("second", "minute", "hour", "day", "week", "month", "year", "decade");
   $lengths = array("60","60","24","7","4.35","12","10");

   $now = time();

       $difference     = $now - $time;
       $tense         = "ago";

   for($j = 0; $difference >= $lengths[$j] && $j < count($lengths)-1; $j++) {
       $difference /= $lengths[$j];
   }

   $difference = round($difference);

   if($difference != 1) {
       $periods[$j].= "s";
   }

   return "$difference $periods[$j] 'ago' ";
}

九、裁剪图片

$filename= "test.jpg";
list($w, $h, $type, $attr) = getimagesize($filename);
$src_im = imagecreatefromjpeg($filename);

$src_x = '0';   // begin x
$src_y = '0';   // begin y
$src_w = '100'; // width
$src_h = '100'; // height
$dst_x = '0';   // destination x
$dst_y = '0';   // destination y

$dst_im = imagecreatetruecolor($src_w, $src_h);
$white = imagecolorallocate($dst_im, 255, 255, 255);
imagefill($dst_im, 0, 0, $white);

imagecopy($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h);

header("content-type: image/png");
imagepng($dst_im);
imagedestroy($dst_im);

十、检查网站是否宕机

function visit($url){
       $agent = "mozilla/4.0 (compatible; msie 5.01; windows nt 5.0)";$ch=curl_init();
       curl_setopt ($ch, curlopt_url,$url );
       curl_setopt($ch, curlopt_useragent, $agent);
       curl_setopt ($ch, curlopt_returntransfer, 1);
       curl_setopt ($ch,curlopt_verbose,false);
       curl_setopt($ch, curlopt_timeout, 5);
       curl_setopt($ch,curlopt_ssl_verifypeer, false);
       curl_setopt($ch,curlopt_sslversion,3);
       curl_setopt($ch,curlopt_ssl_verifyhost, false);
       $page=curl_exec($ch);
       //echo curl_error($ch);
       $httpcode = curl_getinfo($ch, curlinfo_http_code);
       curl_close($ch);
       if($httpcode>=200 && $httpcode<300) return true;
       else return false;
}
if (visit("http://www.google.com"))
       echo "website ok"."n";
else
       echo "website down";