目录结构如下，其中function文件夹下包含两个函数文件，uploads文件夹用于存放上传的文件。

注：博主使用的是php5，使用php7的小伙伴运行报错的话有一部分原因是新的语法造成的，修改成新语法就可以了

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html页面

登录页面
index.html

<form action="login_process.php" method="POST">登录<input type="text" name="userName" size="20" maxlength="15" placeholder="请填写用户名及域名"><br>注册<input type="password" name="password" size="20" maxlength="15"><br><input type="submit" value="登录"><input type="button" onclick="window.location.href='register.html'" value="注册">
</form>

注册页面
register.html

<h2>用户注册登录系统</h2>
<hr>
<form action="register.php" method="POST" enctype="multipart/form-data">用户名：<input type="text" name="userName" size="20" maxlength="15" placeholder="必须填写用户名">@<select name="domain" id=""><option value="@163.com" selected>163.com</option><option value="@126.com">126.com</option></select><br>登录密码：<input type="password" name="password" size="20" maxlength="15"><br>确认密码：<input type="password" name="confirmPassword" size="20" maxlength="15"><br>选择性别：<input type="radio" name="sex" value="male" checked>男<input type="radio" name="sex" value="female">女<br>个人爱好：<input name="interests[]" type="checkbox" value="music">音乐<input name="interests[]" type="checkbox" value="game">游戏<input name="interests[]" type="checkbox" value="film">电影<br>个人相片<input type="hidden" name="MAX_FILE_SIZE" value="1024"><input type="file" name="myPicture" size="25" maxlength="100"><br>备注信息：<textarea name="remark" cols="30" rows="4" placeholder="请填写备注信息"></textarea><br><input type="submit" name="submit" value="注册"><input type="reset" name="cancel" value="重填">
</form>

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功能实现文件

实现登录功能
login_process.php

<?phpinclude_once("function/database.php");// $userName = $_POST['userName'];// $password = $_POST['password'];$userName = addslashes($_POST['userName']);$password = addslashes($_POST['password']);getConnect();$loginSQL = "select * from users where userName='$userName' and password='$password'";echo $loginSQL;$resultLogin = mysql_query($loginSQL);if (mysql_num_rows($resultLogin) > 0) {echo "登录成功";} else {echo "登录失败";}closeConnect();
?>

实现注册功能
register.php

<?phpinclude_once("function/fileSystem.php");include_once("function/database.php");if (empty($_POST)) {exit("您提交的表单数据超过post_max_size! <br>");}// 判断输入密码与确认密码是否相同$password = $_POST['password'];$confirmPassword = $_POST['confirmPassword'];if ($password != $confirmPassword) {exit("输入的密码与确认密码不相等！");}$userName = $_POST['userName'];$domain = $_POST['domain'];$userName = $userName . $domain;// 判断用户名是否重复$userNameSQL = "select * from users where userName = '$userName'";getConnect();$resultSet = mysql_query($userNameSQL);if (mysql_num_rows($resultSet) > 0) {exit("用户名已被占用，请更换其他用户名");}$sex = $_POST['sex'];if (empty($_POST['interests'])) {$interests = "";} else {$interests = implode(";", $_POST['interests']);}$remark = $_POST['remark'];$myPictureName = $_FILES['myPicture']['name'];$registerSQL = "insert into users values(null, '$userName', '$password', '$sex', '$interests', '$myPictureName', '$remark')";$message = upload($_FILES['myPicture'], "uploads");if ($message == "上传成功" || $message == "没有上传") {mysql_query($registerSQL);$userID = mysql_insert_id();echo "注册成功<br>";} else {exit($message);}$userSQL = "select * from users where user_id = '$userID'";$userResult = mysql_query($userSQL);if ($user = mysql_fetch_array($userResult)) {echo "您的注册用户名为：" . $user['userName'];} else {exit("用户注册失败！");}closeConnect();

函数文件（function文件夹）

实现数据库连接与关闭的函数
database.php

<?php$databaseConnection = null;function getConnect() {$hosthome = "localhost";$database = "register";$userName = "root";$password = "123456";global $databaseConnection;$databaseConnection = @mysql_connect($hosthome, $userName, $password) or die (mysql_error());mysql_query("set names gbk");@mysql_select_db($database, $databaseConnection) or die (mysql_error());}function closeConnect() {global $databaseConnection;if ($databaseConnection) {@mysql_close($databaseConnection) or die (mysql_error());}}
?>

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实现文件上传的函数
fileSystem.php

<?phpfunction upload($file, $filePath) {$error = $file['error'];switch ($error) {case 0:$fileName = $file['name'];$fileTemp = $file['tmp_name'];$destination = $filePath . "/" . $fileName;move_uploaded_file($fileTemp, $destination);return "上传成功";case 1:return "上传超过upload_max_filesize";case 2:return "上传文件超过form的MAX_FILE_SIZE";case 3:return "附件部分上传";case 4:return "没有上传";}}
?>