I am trying to use php and html to read in a number and check to see if it is prime, but when I first open the php file I get an error on line 26 saying that i have an Undefined array key "number" on line 26, but if i type in a number the error goes away and the code runs fine, and can correctly tell if it was a prime number or not. Is there some way to get rid of this error? Here is the code for reference
<!DOCTYPE html>
<html lang="en">
<body>
<p> Please enter a whole number. <br></p>
<form method = "GET">
<input type = "number" name = "number" id = "number">
<input type="submit" name = "submit" value = "Go!">
</form>
<?php
function isPrime($num)
{
if ($num == 1)
return false;
for ($i = 2; $i <= $num/2; $i++)
{
if ($num % $i == 0)
return false;
}
return true;
}
$num = $_GET['number'];
if(isPrime($num))
echo "It is a prime number";
else
echo "It is not a prime number"
?>
</body>
</html>
