$ _POST无法正常工作。 “注意：未定义索引：用户名...” [英] $_POST not working. "Notice: Undefined index: username..."
问题描述
可能重复：
PHP：注意：未定义变量和通知：未定义索引
所以，我目前正在学习PHP，正在读一本关于密码的md5函数的书，所以我决定尝试一下，看看它是怎么回事。我还决定使用POST方法而不是GET，因为我看到有人说它更安全，并且不会让变量出现在URL上。
So, I am currently learning PHP and was reading on a book about the md5 function for passwords, so I decided to give it a try and see how it goes. I also decided to use the POST method rather than the GET, since I saw people saying that it is safer and doesn't let the variables appearing on the URL.
For我的测试项目我做了一个非常简单的表格，如下：
For my testing project I made a very simple form, which follows:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title></title>
</head>
<body>
<form action="dologin" method="POST">
<table border="0">
<tbody>
<tr>
<td>Username:</td>
<td><input type="text" name="username"></td>
</tr>
<tr>
<td>Password:</td>
<td><input type="password" name="password"></td>
</tr>
</tbody>
</table>
<input type="submit" value="Login">
</form>
</body>
</html>
问题是，当我在BOTH字段中输入值并点击Login时，我得到以下内容另一个PHP文件的输出。
The problem is that when I enter the values on BOTH fields and click "Login" I get the following output on the other PHP file.
Notice: Undefined index: username in C:\xampp\htdocs\md5\home\dologin\index.php on line 11
Username non existent
这里遵循/dologin/index.php文件的代码
Here follows the code for the "/dologin/index.php" file
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title></title>
</head>
<body>
<?php
mysql_connect("localhost", "root") or die(mysql_error());
mysql_select_db("test") or die(mysql_error());
$query = "SELECT password FROM users WHERE username='".$_POST['username']."'";
$result = mysql_query($query);
$row = mysql_num_rows($result);
if(isset($row)){
$password = (mysql_result($result,$row - 1));
$enteredpassword = md5("w@#$@#".$_GET['password']."^#3f%#^");
if($password == $enteredpassword){
if(!isset($_COOKIE['PHPSESSID'])){
session_start();
}
$_SERVER['LOGIN_STATUS'] = true;
} else {
die("Access denied");
}
} else {
die("Username non existent");
}
?>
</body>
</html>
非常感谢我对此问题的任何帮助，感谢您阅读。
Any help at all on my issue is very much appreciated, thank you for reading.
推荐答案
未定义索引意味着在$ _POST数组中的某个地方，没有索引（键）键用户名。
undefined index means that somewhere in the $_POST array, there isn't an index (key) for the key username.
您应该将发布的值设置为变量以获得更清晰的解决方案，这是一个很好的习惯。
You should be setting your posted values into variables for a more clean solution, and it's a good habit to get into.
如果我遇到类似的错误，我会这样做：
If I was having a similar error, I'd do something like this:
$username = $_POST['username']; // you should really do some more logic to see if it's set first
echo $username;
如果用户名没有出现，那就意味着我搞砸了某个地方。你也可以，
If username didn't turn up, that'd mean I was screwing up somewhere. You can also,
var_dump($_POST);
查看您发布的内容。就调试而言，var_dump非常有用。看看： var_dump
To see what you're posting. var_dump is really useful as far as debugging. Check it out: var_dump
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