if(isset($_POST['button1'])) {
echo "This is Button1 that is selected";
}
<!DOCTYPE HTML>
<html>
<?php
function runMyFunction() {
echo 'I just ran a php function';
}
if (isset($_GET['hello'])) {
runMyFunction();
}
?>
Hello there!
<a href='index.php?hello=true'>Run PHP Function</a>
</html>