我想用php写txt上的某一行。

<?php
function modifyTxtLine($filename, $lineNumber, $newContent) {
    $tempFile = 'temp.txt';
    $handle = fopen($filename, 'r+');
    $tempHandle = fopen($tempFile, 'w');

    $count = 0;
    while (($buffer = fgets($handle)) !== false) {
        $count++;
        if ($count == $lineNumber) {
            fwrite($tempHandle, $newContent . "\n");
        } else {
            fwrite($tempHandle, $buffer);
        }
    }

    fclose($handle);
    fclose($tempHandle);

    rename($tempFile, $filename);
}

$filename = 'example.txt';
$lineNumber = 3;
$newContent = 'This is the modified line.';

modifyTxtLine($filename, $lineNumber, $newContent);
?>