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    ▪php读取操作大文件的方法详解      1、直接采用file函数来操作 注：由于 file函数是一次性将所有内容读入内存，而php为了防止一些写的比较糟糕的程序占用太多的内存而导致系统内存不足，使服务器出现宕机，所以默认情况下.........

    ▪php json_encode函数的替代方法(可显示中文)      json_encode是ajax应用中的一个函数，json_encode的使用条件比较苛刻的，需要在php 5.2.0以上并且需要PECL json在1.2.0以上才可以使用。 本文提供的json_encode的替代方法，出自php在线手册中一个示例，.........

    ▪php隐藏文件的真实下载地址的实例代码      代码如下：   代码示例: <?php /**  * 隐藏文件的真实下载地址  * Edit www. */  $file_name = "info_check.exe";   $file_dir = "/www/files/";         //检查文件是否存在   if(!file_exists($file_dir .........

代码示例:

<?php
 ini_set('memory_limit','-1'); 
 $file = 'access.log'; 
 $data = file($file); 
 $line = $data[count($data)-1]; 
 echo $line; 
?>
 

代码示例:

<?php
file = 'access.log'; 
 $file = escapeshellarg($file); // 对命令行参数进行安全转义 
 $line = `tail -n 1 $file`; 
 echo $line; //by www.
?>
 

代码示例:

<?php
 $fp = fopen($file, "r"); 
 $line = 10; 
 $pos = -2; 
 $t = " "; 
 $data = ""; 
 while ($line > 0) { 
  while ($t != "\n") { 
   fseek($fp, $pos, SEEK_END); 
   $t = fgetc($fp); 
   $pos --; 
  } 
  $t = " "; 
  $data .= fgets($fp); 
  $line --; 
 } 
 fclose ($fp); 
 echo $data 
?>
 

代码示例:

<?php
 $fp = fopen($file, "r"); 
 $num = 10; 
 $chunk = 4096; 
 $fs = sprintf()("%u", filesize($file)); 
 $max = (intval($fs) == PHP_INT_MAX) ? PHP_INT_MAX : filesize($file); 
 for ($len = 0; $len < $max; $len += $chunk) {   
  $seekSize = ($max - $len &gt; $chunk) ? $chunk : $max - $len; 
  fseek($fp, ($len + $seekSize) * -1, SEEK_END); 
  $readData = fread($fp, $seekSize) . $readData; 
   
  if (substr_count($readData, "\n") &gt;= $num + 1) { 
   preg_match("!(.*?\n){".($num)."}$!", $readData, $match); 
   $data = $match[0]; 
   break; 
  } 
 } 
 fclose($fp); 
 echo $data; 
?>
 

代码示例:

<?php
 function tail($fp,$n,$base=5) 
 { 
  assert($n>0); 
  $pos = $n+1; 
  $lines = array(); 
  while(count($lines)< =$n){ 
   try{ 
    fseek($fp,-$pos,SEEK_END); 
   } catch (Exception $e){ 
    fseek(0); 
    break; 
   } 
   $pos *= $base; 
   while(!feof($fp)){ 
    array_unshift($lines,fgets($fp)); 
   } 
  } 
  return array_slice($lines,0,$n); 
 } 
 var_dump(tail(fopen("access.log","r+"),10)); 
?>
 

代码示例:

<?php
/**
 * json_encode的替代函数
 * Edit www.
*/
    function jsonEncode($var) { 
        if (function_exists('json_encode')) { 
            return json_encode($var); 
        } else { 
            switch (gettype($var)) { 
                case 'boolean': 
                    return $var ? 'true' : 'false'; // Lowercase necessary! 
                case 'integer': 
                case 'double': 
                    return $var; 
                case 'resource': 
                case 'string': 
                    return '"'. str_replace()(array("\r", "\n", "<", ">", "&"), 
                        array('\r', '\n', '\x3c', '\x3e', '\x26'), 
                        addslashes()($var)) .'"'; 
                case 'array': 
                    // Arrays in JSON can't be associative. If the array is empty or if it 
                    // has sequential whole number keys starting with 0, it's not associative 
                    // so we can go ahead and convert it as an array. 
                    if (emptyempty ($var) || array_keys()($var) === range(0, sizeof($var) - 1)) { 
                        $output = array(); 
                        foreach ($var as $v) { 
                            $output[] = jsonEncode($v); 
                        } 
                        return '[ '. implode(', ', $output) .' ]'; 
                    } 
                    // Otherwise, fall through to convert the array as an object. 
                case 'object': 
                    $output = array(); 
                    foreach ($var as $k => $v) { 
                        $output[] = jsonEncode(strval($k)) .': '. jsonEncode($v); 
                    } 
                    return '{ '. implode(', ', $output) .' }'; 
                default: 
                    return 'null'; 
            } 
        } 
    }
     
    echo jsonEncode(array('first'=>'testing','second'=>'tangjili')); 
?>

代码示例:

<?php 
    function php_json_encode( $data ) { 
        if( is_array($data) || is_object($data) ) { 
            $islist = is_array($data) && ( emptyempty($data) || array_keys($data) === range(0,count($data)-1) ); 
            if( $islist ) $json = '[' . implode(',', array_map('php_json_encode', $data) ) . ']'; 
            else { 
                $items = Array(); 
                foreach( $data as $key => $value ) $items[] = php_json_encode("$key") . ':' . php_json_encode($value); 
                $json = '{' . implode(',', $items) . '}'; 
            } 
        } elseif( is_string($data) ) { 
            $string = '"' . addcslashes()($data, "\\\"\n\r\t/" . chr(8) . chr(12)) . '"'; 
     
            $json    = ''; 
            $len    = strlen($string); 
            for( $i = 0; $i < $len; $i++ ) { 
                $char = $string[$i]; 
     
                $c1 = ord($char); 
                if( $c1 <128 ) { $json .= ($c1 > 31) ? $char : sprintf()("\\u%04x", $c1); continue; } 
                $c2 = ord($string[++$i]); 
                if ( ($c1 & 32) === 0 ) { $json .= sprintf("\\u%04x", ($c1 - 192) * 64 + $c2 - 128); continue; } 
                $c3 = ord($string[++$i]); 
                if( ($c1 & 16) === 0 ) { $json .= sprintf("\\u%04x", (($c1 - 224) <<12) + (($c2 - 128) << 6) + ($c3 - 128)); continue; } 
                $c4 = ord($string[++$i]); 
                if( ($c1 & 8 ) === 0 ) { 
                    $u = (($c1 & 15) << 2) + (($c2>>4) & 3) - 1; 
                    $w1 = (54<<10) + ($u<<6) + (($c2 & 15) << 2) + (($c3>>4) & 3); 
                    $w2 = (55<<10) + (($c3 & 15)<<6) + ($c4-128); 
                    $json .= sprintf("\\u%04x\\u%04x", $w1, $w2); 
                } 
            } 
        }  
        else $json = strtolower()(var_export( $data, true )); 
         
        return $json; 
    }
    echo php_json_encode(array('first'=>'testing')); 
?>

代码示例:

<?php
    function arrayRecursive(&$array, $function, $apply_to_keys_also = false) 
    { 
        foreach ($array as $key => $value) { 
            if (is_array($value)) arrayRecursive($array[$key], $function, $apply_to_keys_also); 
            else $array[$key] = $function($value); 
     
            if ($apply_to_keys_also && is_string($key)) { $new_key = $function($key); if ($new_key != $key) { $array[$new_key] = $array[$key]; unset($array[$key]); } } 
        } 
    } 
?>

代码示例:

<?php
    function JSON($array) { 
        arrayRecursive($array, 'urlencode', true); 
        $json = jsonEncode($array); // 或者 $json = php_json_encode($array); 
        return urldecode($json); 
    } 
     
    echo JSON(array('first'=>'testing','second'=>'中文'));
?>

代码示例:

<?php
/**
 * 隐藏文件的真实下载地址
 * Edit www.
*/
 $file_name = "info_check.exe"; 
 $file_dir = "/www/files/"; 
     
 //检查文件是否存在 
 if(!file_exists($file_dir . $file_name)) exit('文件找不到'); 
 else  
 { 
     $file = fopen($file_dir . $file_name,"r"); // 打开文件 
     
     // 输入文件标签 
     Header("Content-type: application/octet-stream"); 
     Header("Accept-Ranges: bytes"); 
     Header("Accept-Length: ".filesize($file_dir . $file_name)); 
     Header("Content-Disposition: attachment; filename=" . $file_name); 
     
     // 输出文件内容 
     echo fread($file,filesize($file_dir . $file_name)); 
     fclose($file); 
     exit; 
 } 
?> 

代码示例:

<?php
/**
* http ftp文件下载地址隐藏
* Edit www.
*/
 $file_name = "info_check.exe"; 
 $file_dir = "http://www./"; 
 $file = @ fopen($file_dir . $file_name,"r"); 
     
 if (!$file) exit('文件找不到'); 
 else { 
     Header("Content-type: application/octet-stream"); 
     Header("Content-Disposition: attachment; filename=" . $file_name); 
     while (!feof ($file)) { 
  echo fread($file,50000); 
     } 
     fclose ($file); 
 } 
?>