php - 在 php 脚本中定义变量

Question

我买了书“PHP 和 MySql Web 开发”(2008 年 10 月)，但不明白以下代码应该如何工作。这应该是首页并输出:

但是一旦加载， undefined variable 就会出现第一次错误。长脚本，相关部分是定义变量的开始。

    <?php
// This file is the main body of the Warm Mail application.
// It works basically as a state machine and shows users the
// output for the action they have chosen.

//*****************************************************************************
// Stage 1: pre-processing
// Do any required processing before page header is sent
// and decide what details to show on page headers
//*****************************************************************************

  include ('include_fns.php');
  session_start();
  //create short variable names
  @$username = $_POST['username'];
  @$passwd = $_POST['passwd'];
  @$action = $_REQUEST['action'];
  @$account = $_REQUEST['account'];
  @$messageid = $_GET['messageid'];

  @$to =  $_POST['to'];
  @$cc =  $_POST['cc'];
  @$subject =  $_POST['subject'];
  @$message =  $_POST['message'];

  @$buttons = array();

  //append to this string if anything processed before header has output
  $status = '';

  // need to process log in or out requests before anything else
  if ($username || $password) {
    if(login($username, $passwd)) {
      $status .= "<p style=\"padding-bottom: 100px\">Logged in successfully.</p>";
      $_SESSION['auth_user'] = $username;
      if(number_of_accounts($_SESSION['auth_user'])==1) {
        $accounts = get_account_list($_SESSION['auth_user']);
        $_SESSION['selected_account'] = $accounts[0];
      }
    } else {
      $status .= "<p style=\"padding-bottom: 100px\">Sorry, we could not log you in with that
                  username and password.</p>";
    }
  }

  if($action == 'log-out') {
    session_destroy();
    unset($action);
    $_SESSION=array();
  }

  //need to process choose, delete or store account before drawing header
  switch ($action) {
    case 'delete-account':
      delete_account($_SESSION['auth_user'], $account);
    break;

    case 'store-settings':
      store_account_settings($_SESSION['auth_user'], $_POST);
    break;

    case 'select-account':
      // if have chosen a valid account, store it as a session variable
      if(($account) && (account_exists($_SESSION['auth_user'], $account))) {
        $_SESSION['selected_account'] = $account;
      }
    break;
  }

  // set the buttons that will be on the tool bar
  $buttons[0] = 'view-mailbox';
  $buttons[1] = 'new-message';
  $buttons[2] = 'account-setup';

  //only offer a log out button if logged in
  if(check_auth_user()) {
    $buttons[4] = 'log-out';
  }

//*****************************************************************************
// Stage 2: headers
// Send the HTML headers and menu bar appropriate to current action
//*****************************************************************************
  if($action) {
    // display header with application name and description of page or action
    do_html_header($_SESSION['auth_user'], "Warm Mail - ".
                   format_action($action),
                   $_SESSION['selected_account']);
  } else {
    // display header with just application name
    do_html_header($_SESSION['auth_user'], "Warm Mail",
                   $_SESSION['selected_account']);
  }

  display_toolbar($buttons);

//*****************************************************************************
// Stage 3: body
// Depending on action, show appropriate main body content
//*****************************************************************************
  //display any text generated by functions called before header
  echo $status;

  if(!check_auth_user()) {
    echo "<p>You need to log in";

    if(($action) && ($action!='log-out')) {
      echo " to go to ".format_action($action);
    }
    echo ".</p>";
    display_login_form($action);
  } else {
    switch ($action) {
      // if we have chosen to setup a new account, or have just added or
      // deleted an account, show account setup page
      case 'store-settings':

      case 'account-setup':

      case 'delete-account':
        display_account_setup($_SESSION['auth_user']);
      break;

      case 'send-message':
        if(send_message($to, $cc, $subject, $message)) {
          echo "<p style=\"padding-bottom: 100px\">Message sent.</p>";
        } else {
          echo "<p style=\"padding-bottom: 100px\">Could not send message.</p>";
        }
      break;

      case 'delete':
         delete_message($_SESSION['auth_user'],
                        $_SESSION['selected_account'], $messageid);
         //note deliberately no 'break' - we will continue to the next case

      case 'select-account':

      case 'view-mailbox':
        // if mailbox just chosen, or view mailbox chosen, show mailbox
        display_list($_SESSION['auth_user'],
                    $_SESSION['selected_account']);
      break;

      case 'show-headers':
      case 'hide-headers':
      case 'view-message':
        // if we have just picked a message from the list, or were looking at
        // a message and chose to hide or view headers, load a message
        $fullheaders = ($action == 'show-headers');
        display_message($_SESSION['auth_user'],
                        $_SESSION['selected_account'],
                        $messageid, $fullheaders);
      break;

      case 'reply-all':
        //set cc as old cc line
        if(!$imap) {
          $imap = open_mailbox($_SESSION['auth_user'],
                               $_SESSION['selected_account']);
        }

        if($imap) {
          $header = imap_header($imap, $messageid);

          if($header->reply_toaddress) {
            $to = $header->reply_toaddress;
          } else {
            $to = $header->fromaddress;
          }

          $cc = $header->ccaddress;
          $subject = "Re: ".$header->subject;
          $body = add_quoting(stripslashes(imap_body($imap, $messageid)));
          imap_close($imap);

          display_new_message_form($_SESSION['auth_user'],
          $to, $cc, $subject, $body);
        }

      break;

      case 'reply':
        //set to address as reply-to or from of the current message
        if(!$imap) {
          $imap = open_mailbox($_SESSION['auth_user'],
                               $_SESSION['selected_account']);
        }

        if($imap) {
          $header = imap_header($imap, $messageid);
          if($header->reply_toaddress) {
            $to = $header->reply_toaddress;
          } else {
            $to = $header->fromaddress;
          }
          $subject = "Re: ".$header->subject;
          $body = add_quoting(stripslashes(imap_body($imap, $messageid)));
          imap_close($imap);

          display_new_message_form($_SESSION['auth_user'],
                                   $to, $cc, $subject, $body);
        }

      break;

      case 'forward':
        //set message as quoted body of current message
        if(!$imap) {
          $imap = open_mailbox($_SESSION['auth_user'],
                               $_SESSION['selected_account']);
        }

        if($imap) {
          $header = imap_header($imap, $messageid);
          $body = add_quoting(stripslashes(imap_body($imap, $messageid)));
          $subject = "Fwd: ".$header->subject;
          imap_close($imap);

          display_new_message_form($_SESSION['auth_user'],
                                   $to, $cc, $subject, $body);
        }
      break;

      case 'new-message':
        display_new_message_form($_SESSION['auth_user'],
                                 $to, $cc, $subject, $body);
      break;
    }
  }
//*****************************************************************************
// Stage 4: footer
//*****************************************************************************
  do_html_footer();
?>

我知道错误是由于 $_POST 为空，因此 undefined variable ，但为什么会这样写。这段代码有问题还是我遗漏了任何明显的东西。顺便说一句， include ('include_fns.php'); 不会输出任何内容，只是输出一个函数列表。

Answer 1

首先，我想在一切之上开始 session 应该会更好。

就像 simpe 所说，您必须检查您的 GET、POST、SESSION 等值(如果它们设置为任何值)。

如果您想要更好的方法，我建议您检查它们是否已设置且不为空。

例如:考虑像

这样的查询字符串

example.com/index.php?id=16

isset($_GET['id']) 将返回 TRUE。没关系。

但是我试着乱搞一下怎么样:

example.com/index.php?id=

嗯，已经确定了。但空空如也。

所以我建议:

if(isset($_POST['var']) && !empty($_POST['var']))

应该可以解决问题。