PHP程序员最易犯10种错误总结，phper的你中几枪？

??php
// 初始化一个 cURL 对象
$curl = curl_init();

// 设置你需要抓取的URL
curl_setopt($curl, CURLOPT_URL, 'http://www.111cn.net');

// 设置header
curl_setopt($curl, CURLOPT_HEADER, 1);

// 设置cURL 参数，要求结果保存到字符串中还是输出到屏幕上。
curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);

// 运行cURL，请求网页
$data = curl_exec($curl);

// 关闭URL请求
curl_close($curl);

// 显示获得的数据
var_dump($data);
?>

<?
print("<H1>HTTP</H1>n");

// open a file using http protocol
if(!($myFile = fopen("http://www.111cn.net/", "r")))
{
print("file could not be opened");
exit;
}

while(!feof($myFile))
{
// read a line from the file
$myLine = fgetss($myFile, 255);
print("$myLine <BR>n");
}

// close the file
fclose($myFile);

print("<H1>FTP</H1>n");
print("<HR>n");

// open a file using ftp protocol
if(!($myFile = fopen("ftp://ftp.php.net/welcome.msg", "r")))
{
print("file could not be opened");
exit;
}

while(!feof($myFile))
{
// read a line from the file
$myLine = fgetss($myFile, 255);
print("$myLine <BR>n");
}

// close the file
fclose($myFile);

print("<H1>Local</H1>n");
print("<HR>n");

// open a local file
if(!($myFile = fopen("data.txt", "r")))
{
print("file could not be opened");
exit;
}

while(!feof($myFile))
{
// read a line from the file
$myLine = fgetss($myFile, 255);
print("$myLine <BR>n");
}

// close the file
fclose($myFile);
?>

?php

file_get_contents('http://www.111cn.net/');

?>

<?php
 
class HTTPRequest
{
    var $_fp;        // HTTP socket
    var $_url;        // full URL
    var $_host;        // HTTP host
    var $_protocol;    // protocol (HTTP/HTTPS)
    var $_uri;        // request URI
    var $_port;        // port
    
    // scan url
    function _scan_url()
    {
        $req = $this->_url;
        
        $pos = strpos($req, '://');
        $this->_protocol = strtolower(substr($req, 0, $pos));
        
        $req = substr($req, $pos+3);
        $pos = strpos($req, '/');
        if($pos === false)
            $pos = strlen($req);
        $host = substr($req, 0, $pos);
        
        if(strpos($host, ':') !== false)
        {
            list($this->_host, $this->_port) = explode(':', $host);
        }
        else 
        {
            $this->_host = $host;
            $this->_port = ($this->_protocol == 'https') ? 443 : 80;
        }
        
        $this->_uri = substr($req, $pos);
        if($this->_uri == '')
            $this->_uri = '/';
    }
    
    // constructor
    function HTTPRequest($url)
    {
        $this->_url = $url;
        $this->_scan_url();
    }
    
    // download URL to string
    function DownloadToString()
    {
        $crlf = "rn";
        
        // generate request
        $req = 'GET ' . $this->_uri . ' HTTP/1.0' . $crlf
            .    'Host: ' . $this->_host . $crlf
            .    $crlf;
        
        // fetch
        $this->_fp = fsockopen(($this->_protocol == 'https' ? 'ssl://' : '') . $this->_host, $this->_port);
        fwrite($this->_fp, $req);
        while(is_resource($this->_fp) && $this->_fp && !feof($this->_fp))
            $response .= fread($this->_fp, 1024);
        fclose($this->_fp);
        
        // split header and body
        $pos = strpos($response, $crlf . $crlf);
        if($pos === false)
            return($response);
        $header = substr($response, 0, $pos);
        $body = substr($response, $pos + 2 * strlen($crlf));
        
        // parse headers
        $headers = array();
        $lines = explode($crlf, $header);
        foreach($lines as $line)
            if(($pos = strpos($line, ':')) !== false)
                $headers[strtolower(trim(substr($line, 0, $pos)))] = trim(substr($line, $pos+1));
        
        // redirection?
        if(isset($headers['location']))
        {
            $http = new HTTPRequest($headers['location']);
            return($http->DownloadToString($http));
        }
        else 
        {
            return($body);
        }
    }
}
//使用方法
$r = new HTTPRequest('http://www.111cn.net');
$str=$r->DownloadToString();
 
?>

$username=trim($_POST['username']);
$password=md5(trim($_POST['password']));
$ref_url=$_GET['req_url'];
$remember=$_POST['remember'];//是否自动登录标示
$err_msg='';
if($username==''||$password==''){
 $err_msg="用户名和密码都不能为空";
}else{
 $row=getUserInfo($username,$password);
 if(empty($row)){
  $err_msg="用户名和密码都不正确";
 }else{
  $_SESSION['user_info']=$row;
  if(!empty($remember)){//如果用户选择了，记录登录状态就把用户名和加了密的密码放到cookie里面
   setcookie("username",$username,time()+3600*24*365);
   setcookie("password",$password,time()+3600*24*365);
  }
  if(strpos($ref_url,"login.php")===false){
   header("location:".$ref_url);
  }else{
   header("location:main_user.php");
  }
 }
}

//检查用户是否登录
function checklogin(){
 if(empty($_SESSION['user_info'])){//检查一下session是不是为空
  if(empty($_COOKIE['username'])||empty($_COOKIE['password'])){//如果session为空，并且用户没有选择记录登录状
   header("location:login.php?req_url=".$_SERVER['REQUEST_URI']);//转到登录页面，记录请求的url，登录后跳转过去，用户体验好。
  }else{//用户选择了记住登录状态
   $user=getUserInfo($_COOKIE['username'],$_COOKIE['password']);//去取用户的个人资料
  if(empty($user)){//用户名密码不对没到取到信息，转到登录页面
   header("location:login.php?req_url=".$_SERVER['REQUEST_URI']);
  }else{
   $_SESSION['user_info']=$user;//用户名和密码对了，把用户的个人资料放到session里面
  }
  }
 }
}