PHP and Function Errors

Question

I was looking to see what would be the best way to handle errors from functions. Is the "DIE" method appropriate?

ie. php function calls another, for example:

function login(){
     $result = verifyDetails("bob", "password123");
     if($result == "accepted"){
          echo "Welcome bob";
     }else{
          echo "Error!! \n";
          echo $result;
     }
}

function verifyDetails($user, $pass){
     if(empty($user) || empty($pass)){
          die("cannot be empty");
     }

     if($user == "bob" && $pass == "password"){
          return "accepted";
     }else{
          die("username or password incorrect");
     }
}

does the "DIE" method return the message or does everything come to a standstill?

thanks in advance

UPDATE

what if the output is not known?

for example. in the above example I have placed "accepted" as the only correct answer.

What if the return is a name or id number.. then you cant really separate the error and correct returns.

thanks again.

UPDATE / Possible Solution

function login(){
     $result = verifyDetails("bob", "password123");
     if($result[0] == "SUCCESS"){
          echo "Welcome bob";
     }else if($result[0] == "ERROR"){
          echo "Error!! \n";
          echo $result;
     }else{
          echo "Unknown Error!!";
     }

}

function verifyDetails($user, $pass){
     $msg = array();

     if(empty($user) || empty($pass)){
          $msg[0] = "ERROR";
          $msg[1] = "cannot be empty"
          return $msg;
     }

     if($user == "bob" && $pass == "password"){
          //say $customerID is extracted from a db
          $msg[0] = "SUCCESS";
          $msg[1] = $customerID
          return $msg;
     }else{
          $msg[0] = "ERROR";
          $msg[1] = "username or password incorrect"
          return $msg;
     }
}

ideas & suggestions on the above "possible" solution are welcome

UPDATE

Check Shikiryu update 2 answer below for a cleaner version using arrays

You may want to read about Exceptions. Using die() is a relatively good solution when you must terminate the script execution. — mailo
– mailo, Commented Feb 28, 2011 at 13:42
@mailo exceptions shouldn't be used to handle application logic. — Your Common Sense
– Your Common Sense, Commented Feb 28, 2011 at 13:45

Shikiryu · Accepted Answer · 2011-02-28 14:44:52Z

1

die() just echo your message and stop the script because die() is an alias of exit().

In your case, since the password isn't password but password123, the script will stop just displaying "username or password incorrect".

But as I can see here, you want a return "cannot be empty";, so that it'll display :

Error!! username or password incorrect

(and optionally the rest of the html which die() won't)

Update 2 (ugly way) :

function login(){
     $result = verifyDetails("bob", "password123");
     if(isset($result['success']){ // verifyDetails return true?
          echo $result['success'];
     }else{
          echo "Error!! \n";
          echo $result['error']; // Display the error verifyDetails throws
          // You may want to check if $result['error'] exists.
     }
}

function verifyDetails($user, $pass){
     if(empty($user) || empty($pass)){
          return array('error'=>"cannot be empty");
     }

     if($user == "bob" && $pass == "password"){
          return array('success'=>"Welcome bob");
     }else{
          return array('error'=>"username or password incorrect");
     }
}

edited Feb 28, 2011 at 14:44

answered Feb 28, 2011 at 13:39

Shikiryu

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3 Comments

Stevanicus Over a year ago

thanks... the only problem I have if the "return true" is any unknown value... like a customerID or first name" hard to pick what is an error message and what isnt

Shikiryu Over a year ago

@Stevanicus : I updated but I'm not quite satisfied. It works, but looks ugly to me.

Stevanicus Over a year ago

yea that what I put as my possible solution... yours looks cleaner than mine atleast :D but same idea. Like you im not quite satisfied either.

zoltanctoth · Accepted Answer · 2011-02-28 13:39:19Z

1

die terminates the execution of the PHP script at the line it is called. Therefore, your message would no be returned.

You might want to simply use return instead of die;

answered Feb 28, 2011 at 13:39

zoltanctoth

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Comments

Michiel Pater · Accepted Answer · 2011-02-28 13:39:20Z

1

Yes, you could use die() to debug.

does the "DIE" method return the message or does everything come to a standstill?

Yes, it returns the error message and yes, the script will stop continuing.

answered Feb 28, 2011 at 13:39

Michiel Pater

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Comments

Your Common Sense · Accepted Answer · 2011-02-28 14:14:55Z

1

Well the only acceptable way in your case is return FALSE

if these functions are really methods of some class, use class variable to store actual errors. if these functions belongs to no class, I wouldn't use them at all, but write it in plain code

 if($user == "bob" && $pass = "password"){
      echo "Welcome bob";
 }else{
       echo "incorrect username or password");
 }

updated answer

Well there is nothing to invent. Just follow the way PHP goes:
Make your function return either value or FALSE

however, for the validation purpose you have to make it this way:

function validSomething($val){
  return (bool)rand(0,1);
}
$err = array();
if (!validSomething($var)) {
  $err[] = "Whatever error";
}

i.e. function returns only boolean values and actual error message being added by application logic.

However, in your example user-defined functions are totally misused.

edited Feb 28, 2011 at 14:14

answered Feb 28, 2011 at 13:37

Your Common Sense

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9 Comments

Stevanicus Over a year ago

the problem with just returning false is that, you wont know where the error is

Your Common Sense Over a year ago

@Stevanicus see updated answer. make your validation functions check one parameter at a time - so, you will always know. However, talking of such imaginary example a pain. I'd prefer real case to discuss.

Shikiryu Over a year ago

$pass = "password" should be $pass == "password" here, typo ;) ?

Shikiryu Over a year ago

Ouch typo by the OP, my bad :)

Stevanicus Over a year ago

@Col. Shrapnel thanks for that... gave me an idea.. I could always return an array.. with the first "slot" being "success" or "error" for example.

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