calculate distance using latitude longitude

Simple php-mysql query to calculate nearby locations

$sql=mysql_query (“SELECT distinct name, ( 3959 * acos( cos( radians( ‘$lat’ ) ) * cos( radians( lat ) ) * cos( radians( lng ) – radians( ‘$long’ ) ) + sin( radians( ‘$lat’ ) ) * sin( radians( lat ) ) ) ) AS distance FROM markers HAVING distance < ’200′ “);

 

where markers is your table, $lat and $long are point given by you, lat lng are your fields in markers table. Above query will result points upto 200 miles distance.

Creating compressed zip files in php

We can create zip files in php in a very easy way by using phps in built functions. See the function below.

what you need to do is to pass the array of files to this function which you wants to add to zip file. How to list files is described next in  list_dir_files().

<?php

/* 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;
 }
}

?>

   

  

Listing Files To Zip

 

$files_to_zip = list_dir_files(–PATH–);

 

and then pass these files to above function.

<?

 /*********Function to Return file paths in directory and sub directories*********/
 function list_dir_files($src){
  global $err,$files_to_zip;

  $dir = opendir($src);

  while(false !== ( $file = readdir($dir) )) {

   if(($file != ‘.’ && $file != ‘..’)){
    if( is_dir($src. ‘/’ . $file) ) {
     list_dir_files($src . ‘/’ . $file);
    }else {
     //$dest = str_replace(”,”,$src);
     array_push($files_to_zip,$src . ‘/’ . $file);
    }
   }
  }
  closedir($dir);
  return $files_to_zip;
 }

 ?>

php resize image keeping constrants proportions

A simplest and efficient method to resize a image keeping the constraint proportions.

<?
list($width, $height) = getimagesize($image);
$new_dimensions = resize_dimensions($targetwidth,$targetheight,$width,$height);
// Calculates restricted dimensions with a maximum of $target_width by $target_height
function resize_dimensions($target_width,$target_height,$width,$height) {
    $return = array(‘width’ => $width, ‘height’ => $height);
    // If the ratio > target ratio and the width > target width resize down to target width
    if ($width/$height > $target_width/$target_height && $width > $target_width) {
        $return['width'] = $target_width;
        $return['height'] = $target_width/$width * $height;
    }
    // Otherwise, if the height > target, resize down to target height
    else if ($height > $target_height) {
        $return['width'] = $target_height/$height * $width;
        $return['height'] = $target_height;
    }
    return $return;
}
?>

Php running a script in background

Some times we want any script to be run in background which may take a longer time to complete and it should run even if the user session is over.

The nohup linux command is useful for such need. Also we can set priority to this script so that server will not get overloaded due to script.

This will execute your script scriptfile.php in background, It returns process id created by the system which you can use to monitor the process.

<?php

$PID = shell_exec(“nohup php -f scriptfile.php 1>/dev/null & echo $!”);

?>

 

If you want to run this script with a low priority, to avoid system overhead use nice keyword

<?php

$PID = shell_exec(“nohup nice php -f scriptfile.php 1>/dev/null & echo $!”);

?>

 

If you want to pass arguments to this script, the arguments will be available in scriptfile.php in array $_SERVER['argv']

<?php

PID = shell_exec(“nohup nice php -f scriptfile.php $arg1 $arg2 1>/dev/null & echo $!”);

?>

 

You can monitor process status like this

<?php

function is_running($PID){

exec(“ps $PID”, $ProcessState);

if(count($ProcessState) >= 2)

{

return ‘yes’;

}

else{

return ‘no’;

}

}

?>