致命错误:调用未定义的函数httppost()

I am trying to make a project work. But I am getting an error like this:

Class 'App' not found in /var/www/html/project/test.php on line 4

line 4 of this file says:

app::$activepage = $_GET['_page'] ? httpget('_page') : $_POST['_page'] ? httppost('_page') : 0);

I am using cakePhp Version: 1.3.15-1. The weird thing is that when I do apt show cakephp it says State: not installed However, I have followed all the instructions of https://www.digitalocean.com/community/tutorials/how-to-install-cakephp-on-an-ubuntu-12-04-vps and when I open the index.php file of cakephp, it doesn't indicate any errors.

As I said in my Comment:

Your snippet / folder structure doesn't look like CakePHP.

Part of the problem may be a version mismatch. You say you're using version 1.3.15, but the tutorial on installing it that you link was created over a year later and references version 2.3.9. It looks like the general steps are the same, based on comparing your tutorial to the steps in the 2.X blog tutorial. You might have more luck with an older tutorial on using CakePHP on Ubuntu. Most of the steps look similar, but there are some differences with the .htaccess portion that could be causing the problem. Neither the 1.3 or 2.3 versions look like they require any "installing."

If you're not looking at the older version for any particular reason, of course it's best to use the most recent version of CakePHP, but I assume you have a particular reason for using that version. But if you're stuck, you might try a newer version to see if it gives the same errors.