PHP Square Root Calculator (w/ HTML) - php

Question

I've attempted to make a square root calculator with PHP and HTML using form. but it won't seem to get the output statement. Here it is:
<?php
$num = $_POST['getroot'];
$pull_sqrt = print(sqrt($num));
print("The Square root of "$num"is "$pull_sqrt);
?>
<form action="root.php" method="post">
<input type="text" id="getroot" value="Number"/>
<input type="submit" id="submitroot" value="Calculate"/>
</form>
for root.php:
<?php
$num = $_POST['getroot'];
$pull_sqrt = print(sqrt($num));
print("The Square root of "$num"is "$pull_sqrt);
?>
Please help me out on explaining this, I still don't know if PHP allowed sqrt(); as a function anymore. Any way of re-editing is fine, I would like an explained way of fixing this. Thanks!

Answer 1

You don't have a form element named getroot
You want to do <input type="text" id="getroot" name="getroot" value="Number"/>
You cannot rely on just an id. POST requires a "named" element.
You're also missing concatenates for print("The Square root of "$num"is "$pull_sqrt);
Sidenote: Remove print from $pull_sqrt = print(sqrt($num)); otherwise it will echo as 1.
do
print("The Square root of " . $num . "is " .$pull_sqrt);
Since you're using this in one page, you need to use isset() and using action="".
<?php
if(isset($_POST['submit'])){
$num = $_POST['getroot'];
$pull_sqrt = sqrt($num);
print("The Square root of " . $num . " is " . $pull_sqrt);
}
?>
<form action="" method="post">
<input type="text" id="getroot" name="getroot" placeholder="Enter a number"/>
<input type="submit" name="submit" id="submitroot" value="Calculate"/>
</form>
You can also check if it is in fact a number that has been entered, using is_numeric().
<?php
if(isset($_POST['submit'])){
if(is_numeric($_POST['getroot'])){
$num = (int)$_POST['getroot'];
$pull_sqrt = sqrt($num);
print("The Square root of " . $num . " is " . $pull_sqrt);
// Yes, you can do the following:
$pull_sqrt = print($num * $num); // added as per a comment you left, but deleted.
}
else{
echo "You did not enter a number.";
}
}
?>
<form action="" method="post">
<input type="text" id="getroot" name="getroot" placeholder="Enter a number"/>
<input type="submit" name="submit" id="submitroot" value="Calculate"/>
</form>