how to add strings and variables php echo code example

Example 1: how to combine variables and text into a string php

<?php
$number = 8;
$txt = "the number is".$number.", ok?"; //Use a dot to combine
echo $txt;
?>

Example 2: join string php

<?php
$arr = array('Hello','World!','Beautiful','Day!');
echo join(" ",$arr);
?>