<?php
$file_data = array(
   't1|c1|dp1',
   't2|c2|dp2',
   't3|c3|dp3',
);
$file_data_array = array(
     'title'=>array(),
     'content'=>array(),
     'date_posted'=>array()
);
//go through each question
foreach($file_data as $value) {
    //separate the string by pipes and place in variables
    list($title, $content, $date_posted) = explode('|', $value);

    //create an associative array for each input
    $file_data_array['title'][] = $title;
    $file_data_array['content'][] = $content;
    $file_data_array['date_posted'][] = $date_posted;

}

print_r($file_data_array);
?>

Array
(
    [title] => Array
        (
            [0] => t1
            [1] => t2
            [2] => t3
        )

    [content] => Array
        (
            [0] => c1
            [1] => c2
            [2] => c3
        )

    [date_posted] => Array
        (
            [0] => dp1
            [1] => dp2
            [2] => dp3
        )

)