use php's file_put_content() more information here http://php.net/manual/en/function.file-put-contents.php
Update :
assuming that the data is correctly being passed. here is what you can do.
$info = array();
$folder_name = $this->input->post('folder_name');
$info['title'] = $this->input->post('title');
$info['description'] = $this->input->post('description');
$info['code'] = $this->input->post('code');
$json = json_encode($info);
$file = "./videos/overlay.txt";
//using the FILE_APPEND flag to append the content.
file_put_contents ($file, $json, FILE_APPEND);
Update 2:
if you want to access the value back from the text file. overlay.txt here is what you can do
$content = file_get_contents($file);
if you want to fetch title, code, and description separately. and if the string is in json then you need to convert it into array first by using.
//this will convert the json data back to array
$data = json_decode($json);
and to access individual value you can do it like this if you have one row
echo $data['title'];
echo $data['code'];
echo $data['description'];
if you have multiple rows then you can use php foreach loop
foreach($data as $key => $value)
{
$key contains the key for example code, title and description
$value contains the value for the correspnding key
}
hope this helps you.
Update 3:
do it like this
$jsonObjects = file_get_contents('./videos/overlay.txt');
$jsonData = json_decode($jsonObjects);
foreach ($jsonData as $key => $value) {
echo $key . $value;
//$key contains the key (code, title, descriotion) and $value contains its corresponding value
}