Undefined offset: 0

PHP
1

Greetings to everyone:

I am currently working through one PHP and MySQL book and there is a project that involves building some kind of a matchmaking app.

I am getting this error message as I look through the list of user ids with foreach() loop.


Notice: Undefined offset: 0 in C:\\Program Files\\Apache Software Foundation\\Apache2.2\\htdocs\\mymismatch.php on line 59

Notice: Undefined offset: 1 in C:\\Program Files\\Apache Software Foundation\\Apache2.2\\htdocs\\mymismatch.php on line 59

Notice: Undefined offset: 2 in C:\\Program Files\\Apache Software Foundation\\Apache2.2\\htdocs\\mymismatch.php on line 59

Here is the code that generates an error:


for ($i = 0; $i < count($user_responses); $i++)
{
	if (($user_responses[$i]['response']+ $mismatch_responses[$i]['response']) == 3)//line 59 is here
	{
		//we found a mismatch
		$temp_score += 1;
		array_push($temp_array, $user_responses[$i]['topic_name']);
	}
}

The problem has something to do with the if statement, but I don’t know where it is. The code works just fine and below all the “Notice:” statements I get the result that I expect to get.

If someone needs more code, just request and I will send.
Thanks for any help.
Alex.

2

My assumption is that user_response variable and hte mis_matchresponse variable are not the same. In this case your mismatch_response is empty.

If you wanted to do some ugly code rewrite your if statement this way


    if (($user_responses[$i]['response']+ isset($mismatch_responses[$i]['response']) ?$mismatch_responses[$i]['response'] : 0 ) == 3)//line 59 is here

Incase you hadn’t see the ?: operator before it’s the tertiary operator basically it’s an if else statement.

so if oyu have


if ($a) {
   $var = 15;
} else {
    $var = 25;
}

//can be rewritten
$var = $a ? 15 : 25;

Also on a side note you’re not using a foreach loop, you’re using a for loop.

3

Thank you all for your contribution. Assumption of some of you was correct. Mismatch_response array was empty for some of the users I was looping through. As a result, this array was not assigned and therefore the “Undefined offset” notice. I deleted the empty user and I no longer get that message. All that I need to do is to make sure user is not empty and only then add it to user id array and loop through them.

Again, thank you for your help.

4

do a print_r() of $user_responses and $mismatch_responses, and see if the indexes 0, 1 and 2 are there.

5

Before your for loop,


var_dump($mismatch_responses);

i’m guessing your $mismatch_responses isnt filled.