Confused about return statement in user defined function

Question

hi there,

i have few question regarding the return statement.

a) is it compulsory to define a return statement in a user defined function.?

b) is it still valid if i just define a return statement without any parameter? will it return the null value?

c) is the following function valid?

function admin_credential($password = 0, $email = 0) {
     if( $password != 0) {
         $password = sha1($password);
         $query = "UPDATE admins SET password = '$password'";
         $result = mysql_query($query);
         }
     if( $email != 0) {
         $query = "UPDATE admins SET email = '$email'";
         $result = mysql_query($query);            
         }
         return;
         }

Answer 1

a) is it compulsory to define a return statement in a user defined function.?

No.

b) is it still valid if i just define a return statement without any parameter? will it return the null value?

Yes.

c) is the following function valid?

Yes, but $result will be lost because you are not returning it. The return is not really necessary.

Answer 2

a) you do not NEED to return a value at the end of a function in PHP. This is roughly equivalent to C's void function.

b) a return of no value is valid, but it can be confusing to other people looking at your code later, so it's a bad idea to make that your standard practice. Consider returning NULL instead, which will have the same effect.

c) Yes, your function uses valid syntax.

Answer 3

a) is it compulsory to define a return statement in a user defined function.?

No. At times you write functions which do not return anything to the called function, say a function to print a multidimensional array in a pretty way.

b) is it still valid if i just define a return statement without any parameter? will it return the null value?

Yes. Omitting return is same as return without any parameter and both return NULL.

c) is the following function valid?

It is syntactically valid. But it would be more meaningful if you return a boolean value to mark the success/failure of the query. So that the caller knows if the DB update went through fine or not.

EDIT:

"UPDATE admins SET password = '$password'"

The query is missing a WHERE clause. So it effectively updated the password of all users in the admins table.

Answer 4

When you look at PHP tables for user authentication there are many things to consider. You have to mull over how you want to store the data in your tables and how to retrieve it. This means you need to consider how many users are going to have access, and how many user types. If you have a handful of users like even less than 10, I recommend not bothering with database user authentication.

The questions you posed have already been answered effectively but I would urge you to try and avoid complicating your system with a lot of unnecessary features: keep it simple.