PHP有一个空白屏幕[重复]

Question

这是我的代码。

<? 
  define('DB_HOST', 'localhost'); 
  define('DB_NAME', 'practice'); 
  define('DB_USER','root'); 
  define('DB_PASSWORD',''); 
  $con=mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error()); 
  $db=mysql_select_db(DB_NAME,$con) or die("Failed to connect to MySQL: " . mysql_error()); 
  /* $ID = $_POST['user']; $Password = $_POST['pass']; */ 
  function SignIn() { 
      session_start(); //starting the session for user profile page 
      if(!empty($_POST['user'])) //checking the 'user' name which is from Sign-In.html, is it empty or have some text 
      { 
          $query = mysql_query("SELECT * FROM UserName where userName = '$_POST[user]' AND pass = '$_POST[pass]'") or die(mysql_error()); 
          $row = mysql_fetch_array($query) or die(mysql_error()); 
          if(!empty($row['userName']) AND !empty($row['pass'])) { 
             $_SESSION['userName'] = $row['pass']; echo "SUCCESSFULLY LOGIN TO USER PROFILE PAGE..."; 
          } else { 
             echo "SORRY... YOU ENTERD WRONG ID AND PASSWORD... PLEASE RETRY..."; 
          } 
    } 
 } 
 if(isset($_POST['submit'])) { SignIn(); } 
 ?>

我尝试运行它，但它有一个空白屏幕。 PS。对不起我的英语，我是泰国人。

Answer 1

您错过了 function SignIn() 的右大括号 }，它会为此生成语法错误。

您的代码（有错误）：

<?
  define('DB_HOST', 'localhost'); 
  define('DB_NAME', 'practice'); 
  define('DB_USER','root'); 
  define('DB_PASSWORD',''); 
  $con = mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error());
  $db = mysql_select_db(DB_NAME, $con) or die("Failed to connect to MySQL: " . mysql_error());
  /* $ID = $_POST['user']; $Password = $_POST['pass']; */
  function SignIn() {
    session_start(); //starting the session for user profile page if(!empty($_POST['user'])) //checking the 'user' name which is from Sign-In.html, is it empty or have some text { $query = mysql_query("SELECT * FROM UserName where userName = '$_POST[user]' AND pass = '$_POST[pass]'") or die(mysql_error()); $row = mysql_fetch_array($query) or die(mysql_error()); if(!empty($row['userName']) AND !empty($row['pass'])) { $_SESSION['userName'] = $row['pass']; echo "SUCCESSFULLY LOGIN TO USER PROFILE PAGE..."; } else { echo "SORRY... YOU ENTERD WRONG ID AND PASSWORD... PLEASE RETRY..."; } } } if(isset($_POST['submit'])) { SignIn(); } 
?>

下面的代码可以工作（有修复）

<?
  define('DB_HOST', 'localhost'); 
  define('DB_NAME', 'practice'); 
  define('DB_USER','root'); 
  define('DB_PASSWORD',''); 
  $con = mysql_connect(DB_HOST,DB_USER,DB_PASSWORD) or die("Failed to connect to MySQL: " . mysql_error());
  $db = mysql_select_db(DB_NAME, $con) or die("Failed to connect to MySQL: " . mysql_error());
  /* $ID = $_POST['user']; $Password = $_POST['pass']; */
  function SignIn() {
    session_start(); //starting the session for user profile page if(!empty($_POST['user'])) //checking the 'user' name which is from Sign-In.html, is it empty or have some text { $query = mysql_query("SELECT * FROM UserName where userName = '$_POST[user]' AND pass = '$_POST[pass]'") or die(mysql_error()); $row = mysql_fetch_array($query) or die(mysql_error()); if(!empty($row['userName']) AND !empty($row['pass'])) { $_SESSION['userName'] = $row['pass']; echo "SUCCESSFULLY LOGIN TO USER PROFILE PAGE..."; } else { echo "SORRY... YOU ENTERD WRONG ID AND PASSWORD... PLEASE RETRY..."; } } } if(isset($_POST['submit'])) { SignIn(); }
  }
?>

为什么不为 PHP 代码启用错误以查看错误？下面是代码，如果你把文件放在文件的开头，就会开始显示错误。

<?php
  ini_set('display_errors', 'On');
  error_reporting(E_ALL);
?>

另外，session_start(); 应该始终位于页面的开头，而不是任何函数内部。