Make a PHP variable the value of a form Input - html

Question

I want to make a PHP variable the value of a hidden form input. The form is inside of my PHP (I'm echoing the form), and nothing that I have tried works.
Here's my code:
echo '
<div id = "login">
<form action = "process.php" method = "POST">
Name: <input type = "text" name = "name" required>
<!-- Here is where I need to make my PHP variable the value: -->
<input type = "text" name = "referer" style = "display: none" value = "$variable">
<input type = "submit" name = "submit" value = "Enter">
</form>
</div>
';

Answer 1

Try this:
?><!-- exit out of php into html-->
<div id = "login">
<form action = "process.php" method = "POST">
Name: <input type = "text" name = "name" required>
<!--Here is where I need to make my PHP variable the value:-->
<input type = "text" name = "referer" style = "display: none" value = "<?=$variable?>">
<input type = "submit" name = "submit" value = "Enter">
</form>
</div>
<?php // enter back into php
The <?= ?> is a php short tag
Also, if you still want to use echo, try this:
//note: I changed the quotes
echo "
<div id = 'login'>
<form action = 'process.php' method = 'POST'>
Name: <input type = 'text' name = 'name' required>
<input type = 'text' name = 'referer' style = 'display: none' value = '$variable'>
<input type = 'submit' name = 'submit' value = 'Enter'>
</form>
</div>
";
See this Q/A for more info

Answer 2

The usual string replacements "$var" don't work here , as it's all contained within a single quote string which doesn't allow for string replacements. You will have to concatenate manually
echo '
<div id = "login">
<form action = "process.php" method = "POST">
Name: <input type = "text" name = "name" required>
<input type = "text" name = "referer" style = "display: none" value = "' . $variable . '">
<input type = "submit" name = "submit" value = "Enter">
</form>
</div>
';

Answer 3

Try this sample here https://eval.in/506642
echo "
<div id = 'login'>
<form action = 'process.php' method = 'POST'>
Name: <input type = 'text' name = 'name' required>
//Here's where I need to make my PHP variable the value:
<input type = 'text' name = 'referer' style = 'display: none' value = '$variable'>
<input type = 'submit' name = 'submit' value = 'Enter'>
</form>
</div>
";