"Fatal error: Cannot redeclare <function>"

I have a function(this is exactly how it appears, from the top of my file):

<?php
//dirname(getcwd());
function generate_salt()
{
    $salt = '';

    for($i = 0; $i < 19; $i++)
    {
        $salt .= chr(rand(35, 126));
    }

    return $salt;
}
...

And for some reason, I keep getting the error:

Fatal error: Cannot redeclare generate_salt() (previously declared in /Applications/MAMP/htdocs/question-air/includes/functions.php:5) in /Applications/MAMP/htdocs/question-air/includes/functions.php on line 13

I cannot figure out why or how such an error could occur. Any ideas?

This errors says your function is already defined ; which can mean :

• you have the same function defined in two files
• or you have the same function defined in two places in the same file
• or the file in which your function is defined is included two times (so, it seems the function is defined two times)

To help with the third point, a solution would be to use include_once instead of include when including your functions.php file -- so it cannot be included more than once.

Solution 1

Don't declare function inside a loop (like foreach, for, while...) ! Declare before them.

Solution 2

You should include that file (wherein that function exists) only once. So,
instead of :  include ("functions.php");
use:             include_once("functions.php");

Solution 3

If none of above helps, before function declaration, add a check to avoid re-declaration:

if (!function_exists('your_function_name'))   {
  function your_function_name()  {
    ........
  }
}

You're probably including the file functions.php more than once.