PHP：function

1、检测用户位置
使用下面的函数，可以检测用户是在哪个城市访问你的网站

function detect_city($ip) {
                  
        $default = 'UNKNOWN';
           
        $curlopt_useragent = 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2) Gecko/20100115 Firefox/3.6 (.NET CLR 3.5.30729)';
                  
        $url = 'http://ipinfodb.com/ip_locator.php?ip=' . urlencode($ip);
        $ch = curl_init();
                  
        $curl_opt = array(
            CURLOPT_FOLLOWLOCATION  => 1,
            CURLOPT_HEADER      => 0,
            CURLOPT_RETURNTRANSFER  => 1,
            CURLOPT_USERAGENT   => $curlopt_useragent,
            CURLOPT_URL       => $url,
            CURLOPT_TIMEOUT         => 1,
            CURLOPT_REFERER         => 'http://' . $_SERVER['HTTP_HOST'],
        );
                  
        curl_setopt_array($ch, $curl_opt);
                  
        $content = curl_exec($ch);
                  
        if (!is_null($curl_info)) {
            $curl_info = curl_getinfo($ch);
        }
                  
        curl_close($ch);
                  
        if ( preg_match('{<li>City : ([^<]*)</li>}i', $content, $regs) )  {
            $city = $regs[1];
        }
        if ( preg_match('{<li>State/Province : ([^<]*)</li>}i', $content, $regs) )  {
            $state = $regs[1];
        }
           
        if( $city!='' && $state!='' ){
          $location = $city . ', ' . $state;
          return $location;
        }else{
          return $default; 
        }
                  
    }

调用：

<?php
$ip = $_SERVER['REMOTE_ADDR'];
$city = detect_city($ip);
echo $city;
?>

2、验证邮箱地址
有时候，当在网站填写表单，用户可能会输入错误的邮箱地址，这个函数可以验证邮箱地址是否有效。

function is_validemail($email)
{
$check = 0;
if(filter_var($email,FILTER_VALIDATE_EMAIL))
{
$check = 1;
}
return $check;
}

语法：
<?php
$email = "[email protected]";
$check = is_validemail($email);
echo $check;
// If the output is 1, then email is valid.
?>

3、获取用户的真实 IP

function getRealIpAddr()  
{  
    if (!empty($_SERVER['HTTP_CLIENT_IP']))  
    {  
        $ip=$_SERVER['HTTP_CLIENT_IP'];  
    }  
    elseif (!empty($_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;  
}

语法：
<?

php $ip = getRealIpAddr();

echo $ip;

4、阻止多个 IP 访问你的网站
这个代码片段可以方便你禁止某些特定的 IP 地址访问你的网站

if ( !file_exists('blocked_ips.txt') ) {
 $deny_ips = array(
  '127.0.0.1',
  '192.168.1.1',
  '83.76.27.9',
  '192.168.1.163'
 );
} else {
 $deny_ips = file('blocked_ips.txt');
}
// read user ip adress:
$ip = isset($_SERVER['REMOTE_ADDR']) ? trim($_SERVER['REMOTE_ADDR']) : '';
       
// search current IP in $deny_ips array
if ( (array_search($ip, $deny_ips))!== FALSE ) {
 // address is blocked:
 echo 'Your IP adress ('.$ip.') was blocked!';
 exit;
}

5、强制性文件下载
如果你需要下载特定的文件而不用另开新窗口，下面的代码片段可以帮助你。

function force_download($file) 
{ 
    $dir      = "../log/exports/"; 
    if ((isset($file))&&(file_exists($dir.$file))) { 
       header("Content-type: application/force-download"); 
       header('Content-Disposition: inline; filename="' . $dir.$file . '"'); 
       header("Content-Transfer-Encoding: Binary"); 
       header("Content-length: ".filesize($dir.$file)); 
       header('Content-Type: application/octet-stream'); 
       header('Content-Disposition: attachment; filename="' . $file . '"'); 
       readfile("$dir$file"); 
    } else { 
       echo "No file selected"; 
    } 
}

语法：

<php
force_download("image.jpg");
?>

6、压缩 zip 文件
使用下面的 PHP 片段可以即时压缩 zip 文件

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;  
    }  
}
     
语法：
<?php
$files=array('file1.jpg', 'file2.jpg', 'file3.gif');  
create_zip($files, 'myzipfile.zip', true); 
?>

7、解压文件

function unzip($location,$newLocation)
{
        if(exec("unzip $location",$arr)){
            mkdir($newLocation);
            for($i = 1;$i< count($arr);$i++){
                $file = trim(preg_replace("~inflating: ~","",$arr[$i]));
                copy($location.'/'.$file,$newLocation.'/'.$file);
                unlink($location.'/'.$file);
            }
            return TRUE;
        }else{
            return FALSE;
        }
}

语法：

<?php
unzip('test.zip','unziped/test'); //File would be unzipped in unziped/test folder
?>

8、缩放图片

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;   
}

9、目录清单
使用下面的 PHP 代码片段可以在一个目录中列出所有文件和文件夹

function list_files($dir)
{
    if(is_dir($dir))
    {
        if($handle = opendir($dir))
        {
            while(($file = readdir($handle)) !== false)
            {
                if($file != "." && $file != ".." && $file != "Thumbs.db"/*pesky windows, images..*/)
                {
                    echo '<a target="_blank" href="'.$dir.$file.'">'.$file.'</a>'."\n";
                }
            }
            closedir($handle);
        }
    }
}
语法： 
<?php
    list_files("images/"); //This will list all files of images folder
?>

10、获取当前页面 URL
这个 PHP 片段可以帮助你让用户登录后直接跳转到之前浏览的页面

function current_url()
{
$url = "http://" . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
$validURL = str_replace("&", "&", $url);
return validURL;
}

语法：

<?php
echo "Currently you are on: ".current_url();
?>

11、检测 URL 是否有效

function isvalidURL($url)
{
$check = 0;
if (filter_var($url, FILTER_VALIDATE_URL) !== false) {
  $check = 1;
}
return $check;
}
 
语法：
<?php
$url = "http://koonk.com";
$check = checkvalidURL($url);
echo $check; //if returns 1 then URL is valid.
?>

12、生成二维码

function qr_code($data, $type = "TXT", $size ='150', $ec='L', $margin='0')  
{
     $types = array("URL" =--> "http://", "TEL" => "TEL:", "TXT"=>"", "EMAIL" => "MAILTO:");
    if(!in_array($type,array("URL", "TEL", "TXT", "EMAIL")))
    {
        $type = "TXT";
    }
    if (!preg_match('/^'.$types[$type].'/', $data))
    {
        $data = str_replace("\\", "", $types[$type]).$data;
    }
    $ch = curl_init();
    $data = urlencode($data);
    curl_setopt($ch, CURLOPT_URL, 'http://chart.apis.google.com/chart');
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, 'chs='.$size.'x'.$size.'&cht=qr&chld='.$ec.'|'.$margin.'&chl='.$data);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch, CURLOPT_HEADER, false);
    curl_setopt($ch, CURLOPT_TIMEOUT, 30);
    $response = curl_exec($ch);
    curl_close($ch);
    return $response;
}

语法：

<?php
header("Content-type: image/png");
echo qr_code("http://koonk.com", "URL");
?>

13、计算两个地图坐标之间的距离

function getDistanceBetweenPointsNew($latitude1, $longitude1, $latitude2, $longitude2) {
    $theta = $longitude1 - $longitude2;
    $miles = (sin(deg2rad($latitude1)) * sin(deg2rad($latitude2))) + (cos(deg2rad($latitude1)) * cos(deg2rad($latitude2)) * cos(deg2rad($theta)));
    $miles = acos($miles);
    $miles = rad2deg($miles);
    $miles = $miles * 60 * 1.1515;
    $feet = $miles * 5280;
    $yards = $feet / 3;
    $kilometers = $miles * 1.609344;
    $meters = $kilometers * 1000;
    return compact('miles','feet','yards','kilometers','meters'); 
}

语法：

<?php
$point1 = array('lat' => 40.770623, 'long' => -73.964367);
$point2 = array('lat' => 40.758224, 'long' => -73.917404);
$distance = getDistanceBetweenPointsNew($point1['lat'], $point1['long'], $point2['lat'], $point2['long']);
foreach ($distance as $unit => $value) {
    echo $unit.': '.number_format($value,4).'';
}
?>

14、限制文件下载的速度

<?php
// local file that should be send to the client
$local_file = 'test-file.zip';
// filename that the user gets as default
$download_file = 'your-download-name.zip';
   
// set the download rate limit (=> 20,5 kb/s)
$download_rate = 20.5; 
if(file_exists($local_file) && is_file($local_file)) {
    // send headers
    header('Cache-control: private');
    header('Content-Type: application/octet-stream'); 
    header('Content-Length: '.filesize($local_file));
    header('Content-Disposition: filename='.$download_file);
   
    // flush content
    flush();    
    // open file stream
    $file = fopen($local_file, "r");    
    while(!feof($file)) {
   
        // send the current file part to the browser
        print fread($file, round($download_rate * 1024));    
   
        // flush the content to the browser
        flush();
   
        // sleep one second
        sleep(1);    
    }    
   
    // close file stream
    fclose($file);}
else {
    die('Error: The file '.$local_file.' does not exist!');
}
?>

16、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="" false;="" }="" if="" (visit("http:="" www.google.com"))="" echo="" "website="" ok"."n";="" down";<="" pre="">

15、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);

转：https://juejin.im/entry/56c0192032132c0052b4b29e

16、检查网站是否宕机

15、裁剪图片

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