如何在 PHP 中使用其编号将一条线替换为另一条线

Question

hope that you're doing well, I'm trying to implement a script so that I can use it to replace a line with another one in a file, I tried a lot of PHP scripts and Bash codes but they all seem to failed, here what I tried last:

function replace_a_line() {
    $line=3; //includes zero as 1.
    $newdata='this is a test 123';
    $data=file('./txt.txt');
    $data[$line]=$newdata."\r\n";
    $data=implode($data);
    file_put_contents('./txt.txt',$data);
}

My file name is txt.txt

Thank you in advance

Answer 1

I think you almost did it. No need to implode it yourself.file_put_contents does it for you. Add additional checks to make sure line number is something within the number of lines range or append the text to the end.

<?php

function replace_a_line($line = 3,$new_str = 'Your text') {
    $data = file('test.txt');    
    if($line >= count($data)) $data[] = $new_str;
    else  $data[ $line - 1] = $new_str . "\n";
    return file_put_contents('test.txt', $data, LOCK_EX);
}

replace_a_line();