PHP - start_session undefined [关闭]

I've been using session_start() fine with my other PHP files. Now however, I am trying to put functions into one file and then be able to call them from various other PHP files.

I simply have this in one file:

    <?php require("CustomerFunctions.php");
        start_session();
        PrintCustomerTable();
    ?>

However I am getting Fatal error: Call to undefined function start_session()

Again, I am able to use start_session everywhere else in my files but now for some reason it won't work in this file. It has the same result even if I remove the require.

The function you're looking for is called session_start().