function in function

clairence

This is surely a simple solution, but I'm baffled. So I ask...

I have things I'd like to do repetitively, and have made them functions.
And then I have want to do other repetitive actions (more functions) that use those functions as part of the action.

But when I build a function with another function inside, the internal function does not return any values.

Why not?

ex:
Function

function db_select_all($table,$sorter,$sortdir){
 if($sorter!='0'){
	$sortvals='order by '.$sorter;
 }
 if($sortdir!='0'){
	$sortvals.=' '.$sortdir;
 }
 global $tabledata;
   $getdata=mysql_query("select * from $table $sortvals")or die(mysql_error()); // get all the table data
	if($getdata){
		while($row=mysql_fetch_array($getdata)){
			$tabledata[]=$row;
		}
		if($tabledata==''){echo'<br>no tabledata. verify there is data in the table, '.$table.'<br>';exit;}
	}
 return $tabledata;
}

used in this function:

function db_product_categories_sorted(){
  global $categoriessorted;
  products_db_login();	
  $ptable='mydatabasetable';
  $psort='category_ID';
  $psortdir='ASC';
  db_select_all($ptable,$psort,$psortdir);  // *THIS IS THE FUNCTION that's not working
  $categorieswork=$tabledata;
  foreach($categorieswork as $catkey=>&$catval){
		## do some work with the data
  }
  $categoriessorted=$categorieswork;
  return $categoriessorted;
}

when I try to run this, I get "invalid argument supplied for foreach" because there is no value returned as $tabledata in the second function.

What am I doing wrong?

Weedpacket

  db_select_all($ptable,$psort,$psortdir);  // *THIS IS THE FUNCTION that's not working

It returns results, but you never put them anywhere.

The results aren't going to be put into $tabledata (as you seem to think). You have two different variables named $tabledata - one is a local variable in db_product_categories_sorted(), and one that you've declared to be global in db_select_all(). (You don't have one function inside another; you have two functions and one calls the other.)

So lose the "global $tabledata" declaration and change the line that isn't working to

$tabledata =  db_select_all($ptable,$psort,$psortdir);  // *THIS IS THE FUNCTION that's not working

And you look like you may be making the same mistake about what [man]global[/man] means regarding $categoriessorted.

clairence

Thanks so much! Your suggestion worked. I'm still a little confused, though. Please indulge my curiosity.

I am using the db_select_all() function in another place, and it DOES return the array $tabledata. When I commented out the global declaration, the data disappeared from that place.

ex:

vendors_db_login();
			$vtable='mydatabasetable';
			$vsort='vendor_name';
			$vsortdir='ASC';
			db_select_all($vtable,$vsort,$vsortdir);
			$form_build['vendor']=$tabledata;

this does put the $tabledata array into $form_build['vendor'].

Doing this all in-line was my workaround since it didn't work when I wrapped it in a function declaration like so:

function db_vendor_list($sortparam,$sortdir){
   global $vendorlist;
   require_once('db_logins.php');
   vendors_db_login();
       $vtable='mydatabasetable';
       $vsort=$sortparam;
       $vsortdir=$sortdir;
       db_select_all($vtable,$vsort,$vsortdir);
       $vendorlist=$tabledata; 
       return $vendorlist;
}

To my eye, the function does exactly the same thing as the non-function, but $vendorlist is empty while $form_build['vendor'] is populated.

Can you explain why that is?

(I now see that db_vendor_list() also works when I've commented out the global $tabledata declaration) I just don't see why.

Weedpacket

clairence wrote:
I am using the db_select_all() function in another place, and it DOES return the array $tabledata

Yes, it does, but you never put that returned array anywhere. You just call the db_select_all() function and ignore the result (see the examples in the manual regarding returning values.

PHP has two scopes: global and local. Superglobals notwithstanding:

A global variable is visible outside of any function, and inside functions that "import" it using the [man]global[/man] keyword. Generally speaking, global variables are more hassle in the long run than they're worth, which is why the extra effort is needed to use them.
A local variable is visible only inside the function where it is used, and is a completely different beast from any other similarly-named variable in any other function. In particular, a function doesn't inherit any local variables from any function calling it.

The two variables named $tabledata in the two functions are different variables. In db_product_categories_sorted(), it appears precisely once and isn't even given a value. It certainly doesn't contain an array, which means $categorieswork won't contain an array either, which means trying to use foreach() to iterate over its elements will fail.

I am using the db_select_all() function in another place, and it DOES return the array $tabledata. When I commented out the global declaration, the data disappeared from that place.

To my eye, the function does exactly the same thing as the non-function, but $vendorlist is empty while $form_build['vendor'] is populated.

The "non-function" (by which I guess means that it lies outside any function) would use the global $tabledata variable. The function uses a local variable named $tabledata (to which you never assign a value).

This just highlights the sort of mess that global variables can cause: you end up having no idea whether they're even defined or not when you try to use them. The solution is to avoid using global variables, and keep in mind that variables in different functions are different variables. Like I said, you seemed confused about what [man]global[/man] is for (if it's a global variable, why would you want to return its value?). And before you think you can fix it by putting [font=monospace]global $tabledata;[/font] back in everywhere, so that $tabledata always referred to the global variable, let me warn that I can see other bugs waiting for you if you do so.