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Question

I have a code that counts how many time a user visited a page. I am trying to display a special message when somebody visits for the 5th time.

   <?php
session_start();
if (empty($_SESSION['count'])) {
    $_SESSION['count'] = 1;
} if($_SESSION['count'] === 5){
    echo '<p> This is your' . $_SESSION['count'] . 'th time! Glad to have you back! </p>';
}if($_SESSION['count'] === 10) {
    echo '<p> This is your' . $_SESSION['count'] . 'th time! You must love it here</p>';
}if($_SESSION['count'] === 20){
    echo '<p> Hi again, this is your' . $_SESSION['count'] . 'th time! This will restart the page. Thanks for visiting so much! </p>';
    $_SESSION['count'] = 0;
} else {
    $_SESSION['count']++;
}

?>

<p> Hello Visitor! You have seen this page <?php echo $_SESSION['count'];?> times!</p>

Answer 1

Just use a if statement like so

if($_SESSION['count'] >= 5){
    echo '<p> Hello Visitor! You have seen this page ' . $_SESSION['count'] . ' times!</p>';
}

Answer 2

This question has morphed a bit, so I am interpreting what you want because it is not clear. I interpreted that you want mutually exclusive messaging. You do that with an if-then-else chain of statements.

<?php
  session_start();
  if (empty($_SESSION['count'])) {
    $_SESSION['count'] = 1;
  } else {
    $_SESSION['count']++;    
  }

  // Display message
  if ($_SESSION['count'] == 5){
    echo "<p>This is your {$_SESSION['count']}th time! Glad to have you back!</p>";
  } else if ($_SESSION['count'] == 10) {
    echo "<p>This is your {$_SESSION['count']}th time! You must love it here</p>";
  } else if ($_SESSION['count'] == 20) {
    echo "<p>Hi again, this is your {$_SESSION['count']}th time! This will restart the page. Thanks for visiting so much!</p>";
    $_SESSION['count'] = 0;
  } else {
    echo "<p>Hello Visitor! You have seen this page {$_SESSION['count']} times!</p>";
  } 

A cleaner way of doing this is to use a switch statement.

<?php
  session_start();
  if (empty($_SESSION['count'])) {
    $_SESSION['count'] = 1;
  } else {
    $_SESSION['count']++;    
  }

  // Display message
  switch ($_SESSION['count']) {
    case 5:
      echo "<p>This is your {$_SESSION['count']}th time! Glad to have you back!</p>";
      break;
    case 10:
      echo "<p>This is your {$_SESSION['count']}th time! You must love it here</p>";
      break
    case 20:
      echo "<p>Hi again, this is your {$_SESSION['count']}th time! This will restart the page. Thanks for visiting so much!</p>";
      $_SESSION['count'] = 0;
      break
    default:
      echo "<p>Hello Visitor! You have seen this page {$_SESSION['count']} times!</p>";      
  }

Some tips:

1. There is no reason to compute the 5,10,20 messages because you are using equality, so they have to be 5th, 10th, 20th. That is wasted computation. It's also not DRY code. It would be better if you had a function that output that message rather than essentially the same computing code.
2. I used string interpolation, as that reads easier and is easier to update when compared to a lot of string concatenation. When you have an array with single quotes in it, you make that work by wrapping the variable in {} as I did here: {$_SESSION['count']}th time! You use double quotes to tell PHP to interpolate variables into the string.
3. Don't use the php end tag ?> at the end of a script. It's not needed and can introduce some odd output bugs when you are including scripts.

Hopefully you can see that this will only produce one message per visit to the page.