如何在PHP大型数组中匹配指定字符串并获取对应键名？

Hey there! Let's break down why your current code isn't grabbing the right line from your saved BD_Info file, and get you the disk size you need efficiently.

The Problem with Your Current Code #

Your original array_search('TINFO:0,10,0,', $BD_Info_array) call has two key issues:

1. Exact match requirement: array_search looks for elements that are exactly equal to your target string. But each line in your file is something like TINFO: 0,10,0, "36.9 GB" — which includes the target plus extra text (and a space after TINFO: that your search string is missing!).
2. False handling: When array_search can't find an exact match, it returns false. PHP treats false as 0 when used as an array index, so you end up getting the first line of the file instead of the correct matching line.

The Fix: Search for Lines Containing the Target #

Instead of looking for an exact match, we need to check each line to see if it contains your fixed TINFO: 0,10,0, identifier. Here are two reliable ways to do this:

Option 1: Foreach Loop (Simple & Explicit)

This loops through each line and stops as soon as it finds a match, which is efficient for large arrays:

<?php
// Load the file content into an array
$BD_Info_array = file("../BD_Info");
// Target string with the correct space (matches your sample output)
$target_identifier = 'TINFO: 0,10,0,';
$matched_line = null;

foreach ($BD_Info_array as $line) {
    // Trim whitespace/newlines and check if the line contains our target
    if (stripos(trim($line), $target_identifier) !== false) {
        $matched_line = trim($line);
        break; // Stop searching once we find the first match
    }
}

if ($matched_line) {
    // Extract the size (same logic as your original shell command)
    $size = substr($matched_line, strlen($target_identifier) + 1, -1);
    echo $size; // Outputs something like "36.9 GB" or "5.7 GB"
} else {
    echo "Disk size information not found in the file.";
}
?>

Option 2: Array Filter (Concise)

If you prefer a more functional approach, array_filter can filter out all non-matching lines:

<?php
$BD_Info_array = file("../BD_Info");
$target_identifier = 'TINFO: 0,10,0,';

// Filter lines to only those containing the target identifier
$matching_lines = array_filter($BD_Info_array, function($line) use ($target_identifier) {
    return stripos(trim($line), $target_identifier) !== false;
});

if (!empty($matching_lines)) {
    // Get the first matching line
    $matched_line = trim(reset($matching_lines));
    $size = substr($matched_line, strlen($target_identifier) + 1, -1);
    echo $size;
} else {
    echo "Disk size information not found in the file.";
}
?>

Key Notes #

• Case insensitivity: I used stripos instead of strpos to match the -i flag in your original grep command — this ensures it works even if the output has uppercase/lowercase variations.
• Trim whitespace: trim() removes extra newlines or spaces from each line, which prevents false negatives from invisible characters.
• Efficiency: Both methods are way faster than re-running makemkvcon every time, since you're reading from a local file instead of executing an external command.

内容的提问来源于stack exchange，提问作者Sub S7v7n