"Fatal error: Cannot redeclare <function>"
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() { ........ }}