我正在开发一个小型论坛，目前正在尝试在单独的文件中显示论坛主题。无论出于何种原因，当我打开文件时，它显示这些错误:
Notice: Undefined index: cid in C:\xampp\htdocs(A)Book 2.0\Bootstrap\topics.php on line 19
Notice: Undefined index: scid in C:\xampp\htdocs(A)Book 2.0\Bootstrap\topics.php on line 20
Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in C:\xampp\htdocs(A)Book 2.0\Bootstrap\content_function.php on line 41
我尝试对变量使用 isset 函数，但没有成功。我从单独的函数文件中调用变量。
这是显示主题的代码:
<?php
session_start();
require_once ('../db.php');
// Check if user is logged in using the session variable
if ( $_SESSION['logged_in'] != 1 ) {
$_SESSION['message'] = "You must log in before viewing your profile page!";
header("location: error.php");
exit; //<--- add this
}else {
// Makes it easier to read
$first_name = $_SESSION['first_name'];
$last_name = $_SESSION['last_name'];
$email = $_SESSION['email'];
$active = $_SESSION['active'];
}
include ('content_function.php');
$cid2 = $_GET['cid'];
$scid2 = $_GET['scid'];
?>
<!DOCTYPE html>
<html lang = "en">
<head>
<title>Topics</title>
<link href="main.css" type="text/css" rel="stylesheet" />
</head>
<body>
<div class = "content">
<?php
/*
$select = mysqli_query($mysqli, "SELECT * FROM categories");
while($row = mysqli_fetch_assoc($select)){
echo "<h1>", $row['category_title']."</h1>" ;
}*/
disptopics($cid2, $scid2, $mysqli);
/*if (isset($_GET['cid'], $GET['scid'])){
disptopics();
}*/
?>
</div>
</body>
</html>
此外，这是函数的代码:
<?php
require '../db.php';
function dispcategories($mysqli){
$select = mysqli_query($mysqli, "SELECT * FROM categories");
while($row = mysqli_fetch_assoc($select)){
echo "<table class = 'category-table'";
echo "<tr><td class= 'main-category'colspan='2'>".$row['category_title']."</tr></td>";
dispsubcategories($row['cat_id'], $mysqli);
echo "</table>";
}
}
function dispsubcategories($parent_id, $mysqli){
$select = mysqli_query($mysqli, "SELECT cat_id, subcat_id, subcategory_title, subcategory_descr FROM categories, subcategories
WHERE ($parent_id = categories.cat_id) AND ($parent_id = subcategories.parent_id)");
echo "<tr><th width='90%'>Categories</th><th width='10%'>Topics</th></tr>";
while($row = mysqli_fetch_assoc($select)){
echo "<tr><td class='category_title'><a href='topics.php/".$row['cat_id']."/".$row['subcat_id']."'>
".$row['subcategory_title']."<br/>";
echo $row['subcategory_descr']."</a></td>";
echo "<td class='num-topics'>".getnumtopics($parent_id, $row['subcat_id'], $mysqli)."</td></tr>";
}
}
//Displays categories
function getnumtopics($cat_id, $subcat_id, $mysqli){
$select = mysqli_query($mysqli, "SELECT category_id, subcategory_id FROM topics WHERE ".$cat_id." = category_id
AND ".$subcat_id." = subcategory_id");
$get = mysqli_num_rows($select);
return $get;
}
//Displays Topics Within categories
function disptopics($cid, $scid, $mysqli){
$select = mysqli_query($mysqli, "SELECT topic_id, author, title, date_posted, views, replies FROM categories, subcategories, topics
WHERE ($cid = topics.category_id) AND ($scid = topics.subcategory_id) AND ($cid = categories.cat_id)
AND ($scid = subcategories.subcat_id) ORDER BY topic_id DESC");
if(mysqli_num_rows($select) != 0) {
echo "<table class='topic-table'>";
echo "<tr><th>Title</th><th>Posted By</th><th>Date Posted</th><th>Views</th><th>Replies</th></tr>";
while($row = mysqli_fetch_assoc($select)){
echo "<tr><td><a href='readtopic.php/".$cid."/".$scid."/".$row['topic_id']."'>
".$row['title']."</a></td><td>".$row['author']."</td><td>".$row['date-posted'].".</td><td>".$row['views']."</td>
<td>".$row['replies']."</td></tr>";
}
echo "</table>";
} else {
echo "<p>This category has no topics yet! <a href='newtopic.php/".$cid."/".$scid."'> Add a new one!</a></p>";
}
}
?>
我多次检查了每个文件，并使用了代码检查器，显示我没有语法错误。
最佳答案
$_GET 是一个数组，如果用户没有在查询字符串中定义 scid=something，则 $_GET['scid' ] 未定义。在那里，您得到了一个 undefined index 通知。
在尝试读取其值之前，您应该测试是否 isset($_GET['scid'])。
关于php - 我的代码的哪一部分导致了未定义索引错误？ (PHP)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51924069/