Functions within functions HELP!

Anon

Hey'z,

I'm hoping someone can solve this little problem for me. I'm trying to call a function from within a function and it isn't working out how I want it to...

Func 1:

function dbtovars($sql)
{
global $id2,$type2,$beto2,$goto2,$content2,$pjnr2;
$result = mysql_query($sql);
$my_row = mysql_fetch_array($result);
$id2 = $my_row["id"];
$type2 = $my_row["type"];
$beto2 = $my_row["beto"];
$goto2 = $my_row["goto"];
$content2 = $my_row["content"];
$pjnr2 = $my_row["pjnr"];
}

Func 2:

function entrydisplay($admin,$idtomax)
{
dbtovars("SELECT * FROM katalog WHERE id=$idtomax AND type<>'TT' AND type<>'QA' AND type<>'EA'");
echo"<tr><td>";
echo $type2;
echo $idtomax;
switch($type2)
{
case "T" : echo "T";
break;
case "W" : echo "W";
break;
case "Q" : echo "Q"; echo "QE";
break;
case "E" : echo "E"; echo "QE";
break;
default : echo "No Type";
}
echo"</td></tr>";
}

If I call dbtovars outside of the displayentry function and echo the $type vars - it all works out - but when I call the dbtovars function from within displayentry none of the vars seem to get set - or at least they aren't usable from within displayentry. How can I get the displayentry function to utilize the variables that dbtovars sets?

Any help is appreciated 😃

Gazoo...

Anon

Why don't your return the $my_row array instead of atributing the values into other vars?

cordex

Your problem: the Global scope only extends one level. So, a function called from a function will not have access to global variables defined in the main body of a program.

Your solution: redefine global variables in the calling function. In function entrydisplay, add the line:global $id2,$type2,$beto2,$goto2,$content2,$pjnr2;

-Ben

Anon

You should really avoid globals whenever possible.

You might consider using the "return" command at the end of your function. Basically, "return" will send a value back to whatever called it. Like this:

function what_day_is_it() {
// this is just an example
// I'd never suggest such a
// useless function.

$today = "Thursday";
return $today;
}

function generate_message () {
print "Happy ".what_day_is_it()."!";
// or you could do this
$day = what_day_is_it();
print "Happy ".$day."!";
}

Anon

Hey yall,

Thanks for the load of help 😃 But why should I avoid using global vars? Using return is not an option here since I don't wish to set all the vars from $my_row every time I call it (and it will be called often), and returning one value is simply not enough...

Thanks again,

Gazoo...

Anon

Hi!

If you don't like the approach DLB suggested, you may want to consider returning values from a function 'by reference'. At least, this is the option used in C, VB, Delphi, etc, etc.

If you don't know what references are (don't confuse with C pointers), it's an internally-maintained address of a variable. If a variable is passed by reference and you set it to a value, PHP looks up the reference to variable, resolves it and sets the resolved variable to appropriate value.

Actually, global does the same thing - it creates a private variable which contains the address of the variable whose name you specified.

For instance, in this function that check the equality of two variables (rather stupid, I should say), we output additional values:

function check_equal($input1, $input2, &$output1, &$output2)
{
$output1 = "Input variable 1 is ".$input1;
$output2 = "Input variable 2 is ".$input2;

return ($intput - $input2 > 0);
}

This way variables are correctly returned to the calling environment.
PHP is a great language because it allows to return values of different types, but many modern languages don't support it and are type-safe (so the function should only be declared to return a value of one type). For this reason returning by reference is quite a common practice in these languages.

You should note that PHP passes variables into functions by value by default (just like in C).

Hope this has helped.

Best,
Stas

Anon

Hi again!

I would like to note that a variable passed by reference actually never contains the address of a variable (this is what I said in the previous post), it does contain this address internally, but you will never be able to see it.

Stas