php include 引入 php 变量文件打印结果信息

前端页面 index.php

<?php
include "connect.php";
?>

<?php echo "a:".($a); ?> <br>
<?php echo "b:".($b); ?> <br>
<?php echo "c:"."$c"; ?> <br>
<?php echo "d:"."$d"; ?> <br>
<?php echo "e:"."$e"; ?> <br>

后端页面 connect.php

<?php
    $a="1";
    $b="2";
    $c=$a+$b;
    $d=$c+"5";
    $e="10"/"3";
?>