How Can I Find and Display Specific Lines from a Text File Using PHP?

Finding Specific Lines in a Text File Using PHP

Scenario:
You have a text file containing multi-line data that is updated periodically. You need to search the file for a specific piece of data and display the entire corresponding line.

Solution:
To search within a text file and retrieve the entire matching line, follow these steps using PHP:

<?php
$file = 'numorder.txt';
$searchfor = 'aullah1';

// Disable HTML parsing
header('Content-Type: text/plain');

// Read the file contents
$contents = file_get_contents($file);

// Escape special characters in the search phrase
$pattern = preg_quote($searchfor, '/');

// Create a regular expression to match the entire line
$pattern = "/^.*$pattern.*$/m";

// Perform the search
if (preg_match_all($pattern, $contents, $matches)) {
    echo "Found matches:\n";
    echo implode("\n", $matches[0]);
} else {
    echo "No matches found";
}
?>

Explanation:

• The file_get_contents function reads the text file's contents into a variable.
• The preg_quote function escapes special characters in the search phrase, ensuring that it's treated as a literal string.
• The regular expression /^.*$pattern.*$/m matches the entire line containing the search phrase ($pattern). The m flag enables multi-line search.
• The preg_match_all function performs the search, storing any matches in the $matches array.
• The matches are then displayed by iterating over the $matches[0] array, which contains the entire matching lines.

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