PHP代码出现Undefined offset错误，请求排查解决方法

Hey there, let’s break down what’s causing that "Undefined offset" error and fix it up step by step.

What’s Triggering the Error? #

The core issue is your loop runs a hardcoded 50 times, but the $sport and $channel arrays generated by your ara() function almost certainly don’t have 50 elements each. When $i exceeds the last valid index of either array (say, if there are only 12 matches total), trying to access $sport[$i] or $channel[$i] throws the error because that index doesn’t exist.

Also, using the @ error suppressor in your ara() function hides useful debugging clues (like if preg_match_all fails silently) and makes it harder to catch other underlying issues.

Step-by-Step Fixes #

1. Loop Only Through Existing Elements

Instead of forcing 50 iterations, loop only as many times as there are matching elements in both arrays. Use min(count($sport), count($channel)) to get the shorter array length—this ensures you never try to access an element that exists in one array but not the other:

$maxItems = min(count($sport), count($channel));
for ($i = 0; $i < $maxItems; $i++) {
    echo "<span class='linko'><a target='_blank' href='example.org/live1.php?id=" . $channel[$i] . "'>$sport[$i]</a>...</span>";
}

2. Improve the ara() Function

Remove the error suppressor and ensure the function always returns an array (even if no matches are found) using PHP’s null coalescing operator (??):

function ara($one, $two, $three) {
    $matches = [];
    // Only run the regex if input content isn't empty
    if (!empty($three)) {
        preg_match_all('/' . preg_quote($one, '/') . '(.*?)' . preg_quote($two, '/') . '/i', $three, $matches);
    }
    // Return matched group, or empty array if no results
    return $matches[1] ?? [];
}

3. Add Error Handling for file_get_contents

Your $link is missing the HTTP/HTTPS protocol, which will cause file_get_contents to fail. Add the protocol and check if the content was fetched successfully:

$link = "http://example.com"; // Add http:// or https://
$article = file_get_contents($link);
if ($article === false) {
    die("Failed to load the webpage. Check the URL or network connection.");
}

Full Fixed Code #

Here’s the complete code with all fixes (plus an XSS prevention tweak):

function ara($one, $two, $three) {
    $matches = [];
    if (!empty($three)) {
        preg_match_all('/' . preg_quote($one, '/') . '(.*?)' . preg_quote($two, '/') . '/i', $three, $matches);
    }
    return $matches[1] ?? [];
}

$link = "http://example.com";
$article = file_get_contents($link);

if ($article === false) {
    die("Failed to fetch the webpage.");
}

$sport = ara('data-bin="','"',$article);
$channel = ara('data-videobin="','"',$article);

$maxItems = min(count($sport), count($channel));
for ($i = 0; $i < $maxItems; $i++) {
    // Use htmlspecialchars to prevent XSS vulnerabilities
    echo "<span class='linko'><a target='_blank' href='example.org/live1.php?id=" . htmlspecialchars($channel[$i]) . "'>" . htmlspecialchars($sport[$i]) . "</a>...</span>";
}

内容的提问来源于stack exchange，提问作者Ali Keskin