Save PHP variables to a text file

Question

I was wondering how to save PHP variables to a txt file and then retrieve them again.

Example:

There is an input box, after submitted the stuff that was written in the input box will be saved to a text file. Later on the results need to be brought back as a variable. So lets say the variable is $text I need that to be saved to a text file and be able to retrieve it back again.

Answer 1

This should do what you want, but without more context I can't tell for sure.

Writing $text to a file:

$text = "Anything";
$var_str = var_export($text, true);
$var = "<?php\n\n\$text = $var_str;\n\n?>";
file_put_contents('filename.php', $var);

Retrieving it again:

include 'filename.php';
echo $text;

Answer 2

Personally, I'd use file_put_contents and file_get_contents (these are wrappers for fopen, fputs, etc).

Also, if you are going to write any structured data, such as arrays, I suggest you serialize and unserialize the files contents.

$file = '/tmp/file';
$content = serialize($my_variable);
file_put_contents($file, $content);
$content = unserialize(file_get_contents($file));

Answer 3

(Sorry I can't comment just yet, otherwise I would)

To add to Christian's answer you might consider using json_encode and json_decode instead of serialize and unserialize to keep you safe. See a warning from the PHP man page:

Warning

Do not pass untrusted user input to unserialize(). Unserialization can result in code being loaded and executed due to object instantiation and autoloading, and a malicious user may be able to exploit this. Use a safe, standard data interchange format such as JSON (via json_decode() and json_encode()) if you need to pass serialized data to the user.

So your final solution might have the following:

$file = '/tmp/file';
$content = json_encode($my_variable);
file_put_contents($file, $content);
$content = json_decode(file_get_contents($file), TRUE);

Answer 4

for_example, you have anyFile.php, and there is written $any_variable='hi Frank';

to change that variable to hi Jack, use like the following code:

<?php
$content = file_get_contents('anyFile.php'); 

$new_content = preg_replace('/\$any_variable=\"(.*?)\";/', '$any_variable="hi Jack";', $content);

file_put_contents('anyFile.php', $new_content);
?>

Answer 5

Use a combination of of fopen, fwrite and fread. PHP.net has excellent documentation and examples of each of them.

https://www.php.net/manual/en/function.fopen.php
https://www.php.net/manual/en/function.fwrite.php
https://www.php.net/manual/en/function.fread.php

Answer 6

Use serialize() on the variable, then save the string to a file. later you will be able to read the serialed var from the file and rebuilt the original var (wether it was a string or an array or an object)

Answer 7

Okay, so I needed a solution to this, and I borrowed heavily from the answers to this question and made a library: https://github.com/rahuldottech/varDx (Licensed under the MIT license).

It uses serialize() and unserialize() and writes data to a file. It can read and write multiple objects/variables/whatever to and from the same file.

Usage:

<?php
require 'varDx.php';
$dx = new \varDx\cDX; //create an object
$dx->def('file.dat'); //define data file
$val1 = "this is a string";
$dx->write('data1', $val1); //writes key to file
echo $dx->read('data1'); //returns key value from file

See the github page for more information. It has functions to read, write, check, modify and delete data.