我想对从php中的表单发布的值执行逻辑运算

Question

Here is html...

<form name="stream" method="post" action="scripts/validate.php">
  <div class="form-check">
    <input class="form-check-input" type="checkbox" name="attend" value="yes" autocomplete="off">
    <label class="form-check-label" for="attend">Yes, I will attend the event in Edo State.</label>
  </div>
  <div class="form-check">
    <input class="form-check-input" type="checkbox" name="trad" value="yes" autocomplete="off">
    <label class="form-check-label" for="trad">Yes, I'm interested in getting the Asoebi.</label>
  </div>
  <div class="form-check">
    <input class="form-check-input" type="checkbox" name="house" value="yes" autocomplete="off">
    <label class="form-check-label" for="house">Yes, I am interested in getting Accommodation.</label>
  </div>

  <button class="btn bg-bur text-white h4 btn-block mt-20" type="submit" name="stream">Submit</button>
</form>

And here is the php to process the form data but it keeps displaying the same result, "I want the full registration" even when 1 checkbox is checked or none is checked

<?php 
if( isset( $_POST['stream'] ) ) {    
    if ($_POST['attend'] == 'yes' && $_POST['trad'] == 'yes' && $_POST['house'] == 'yes' ) {
        echo "I want the full registration";
    }
    elseif ($_POST['attend'] == 'yes' && $_POST['trad'] == 'yes' && $_POST['house'] !== 'yes' ) {
        echo "I want the Asoebi and I will attend";
    }
    elseif ($_POST['attend'] == 'yes' && $_POST['trad'] !== 'yes' && $_POST['house'] !== 'yes' ) {
        echo "I am only attending";
    }
    elseif ($_POST['attend'] !== 'yes' && $_POST['trad'] == 'yes' && $_POST['house'] !== 'yes' ) {
        echo "I only want Asoebi";
    }
    elseif ($_POST['attend'] !== 'yes' && $_POST['trad'] !== 'yes' && $_POST['house'] !== 'yes' ) {
        echo "You haven't selected anything";
    }
}
?>

Answer 1

When you check the box, $_POST[the name-not-id] comes back with the value. Somewhat annoyingly (to me), checkboxes that are unchecked return nothing at all. So, using the attend as an example:

<input class="form-check-input" type="checkbox" name="attend" value="yes">

would return "yes" in $_POST["attend"] when the box is checked, no value in $_POST when the box is unchecked. So you could use several tests to see if it is checked. For example:

if (!empty($_POST["attend"])) ...

or

if (isset($_POST["attend"]) && $_POST["attend"] === "yes") ...