use function inside another function in WP Plugin

I write a php code that read text file and it is working fine with no problem , have a look at this code.

<?php
function Read($filepath)
{
$myfile = fopen($filepath,"r") or die("Unable to open file!");
$label=fread($myfile,filesize($filepath));
fclose($myfile);
echo $label;
}
?>

now if i try to use Read function inside below input it works fine

 <input type="text" id="txtname" name="txtname" placeholder="<?php Read("resources/name_ar.txt");?>" />

I need to do the same thing using a wordpress plugin but i can’t .
have another look on below code

  <?php
/*
Plugin Name: my plugin
Description: my plugin
Version: 4.0
Author: me
License: GPL
*/
?>
<?php
//PHP Function to read resources files.
function Read($filepath)
{
$myfile = fopen($filepath,"r") or die("Unable to open file!");
$label=fread($myfile,filesize($filepath));
fclose($myfile);
echo $label;
}
?>

<?php 
function  form_creation()
{
    global $wpdb;
    ob_start();
?>
<form action="<?php get_permalink();?>" method="post" id="myform">
<table>
<tr>
<td>
    <h2>Asking Support</h2>
</td>
</tr>
<tr>
<td> <input type="text" id="txtname" name="txtname" placeholder="<?php Read("resources/name_ar.txt");?>" /> </td>
</tr>

</table>
</form>
<?php return ob_get_clean(); } ?>
<?php add_shortcode('myshortcode',form_creation); ?>

now when i use myshortcode nothing displayed and i think that because read function didn’t be accessed , so how can Read function be accessed by form creation function

I tried creating a shortcode in my custom plugin, but in order for it to work, you need to apply a filter that converts all the new shortcodes you created to the content. Where the content is being rendered (like in the single.php file), replace the_content() with
apply_filters('the_content',get_the_content())