form input inside a function.php - php

Question

I have two php files insert.php and function.php
In insert.php
<form action="<?php echo htmlspecialchars( $_SERVER['PHP_SELF'] ); ?>"
method="post">
<input type="hidden" name="Entry" value="<?php print $data; ?>"/>
<hr>
<h3>Entry your new entry</h3>
<?php
include('function.php');
$query_start = "SHOW COLUMNS FROM $data";
$result = mysqli_query( $conn, $query_start );
while($row = mysqli_fetch_array($result)){?>
<label for="<?php echo "$row[0]";?>"><?php display_text($row[0]);?></label>
<br>
<?php display_value($row[0]);
} ?>
<input class="btn btn-primary" type="submit" name="add" value="Add Entry">
</form>
And in function.php
<?php
function display_value($row){?>
<input class='form-control' type='text' placeholder='".$row."' name='".$row."'>
}?>
But I am not getting the form on the web page.

Answer 1

firstly you need to add a <form> tag
<?php
include('function.php');
$query_start = "SHOW COLUMNS FROM $data";
$result = mysqli_query( $conn, $query_start );
while($row = mysqli_fetch_array($result)){
$data = display_value($row[0]);
echo $data;
}
?>
you're just calling that function, for printing the values inside the function, you need to return data from function and store or print the data from you're calling.
$data = display_value($row[0]);
here variable $data will store the output, also you need to return the result from your function
<?php
function display_value($row) {
$data = '<input class="form-control" type="text" placeholder="'. $row .'" name="'. $row .'"><br /><br />';
return $data; //this return will be printed on another page
} ?>

Answer 2

I guess with "form" he meant the fields not the form tag.
#Rohit Sahu answer is wrong.. you dont need to pass the output with a return. Your way of doing it is not a beautiful way. But it is even working this way.
Are you sure your Mysql Query give results?
Example Code:
<?php
// functions.php
function display_value($row) { ?>
<input class='form-control' type="text" placeholder="<?php echo $row;?>" name="<?php echo "$row";?>"><br><br>
<?php } ?>
// insert.php
<form action="....">
<?php
$arr = array(1,2,3,4);
foreach($arr as $row) {
display_value($row);
}?>
</form>
Output:
<form action="....">
<input class='form-control' type="text" placeholder="1" name="1"><br><br>
<input class='form-control' type="text" placeholder="2" name="2"><br><br>
<input class='form-control' type="text" placeholder="3" name="3"><br><br>
<input class='form-control' type="text" placeholder="4" name="4"><br><br>
</form>
Result: It is working fine. You should better post all code to understand where is your mistake. It could be some whitespaces in files, it could be no results from MYSQL.. there are many options. It is difficult to say this way.