Using $arr[]

njm

I have a snippet of code to populate two arrays from a MySQL query:

<?
//$sta = array();
	while ($row = mysql_fetch_assoc($res))
		{
			if ($row['type']==1) $pc[] = $row['dest'];
			else $sta[] = $row['dest'];  // error at this line
		}
?>
<table border="0"><tr><td>Postcode:</td><td><select name="dest">
<?
	foreach($pc as $dest)
		{
			echo "<option value='$dest'>$dest</option>";
		}
?>
</select></td><td><input type="submit" name="getpc" value="go" /> 
<?		
	if (($_POST['getpc']) && ($_POST['dest']))
		{
			$sql = 'SELECT price FROM prices WHERE dest="'.$_POST['dest'].'"';
			$res = $db->qry($sql);
			$row = mysql_fetch_assoc($res);
			echo 'The fare from E4 to '.$_POST['dest'].' would be '.sprintf('£%01.2f',$row['price']);
		}

In 4.3.4, this works fine. However in 4.1.2, I get a fatal error [] operator not supported for strings... unless I uncomment the first line. The error only appears after the submit button has been pressed. Anyone tell me why?

Thanks, njm

Shrike

The error only appears because $res (the SQL resource) is only set once some $_POST variables are set, and so mysql_fetch_array returns false before that.

You also need to declare arrays before using them, hence the error.

njm

Shrike, thanks for the reply.

The $res variable is set before the POST variables are set: The foreach loop gets iterated when the page load, before any form submission is made. Granted I've used the same variable name in two places in the code, but changing that doesn't avert the error.

Why do you need to declare arrays before using them? The manual states:

You can also modify an existing array by explicitly setting values in it. This is done by assigning values to the array while specifying the key in brackets. You can also omit the key, add an empty pair of brackets ("[]") to the variable name in that case.

$arr[key] = value;
$arr[] = value;
// key may be an integer or string
// value may be any value

If $arr doesn't exist yet, it will be created.

Is there something that has changed between versions to modify this behaviour?

regards, njm

LordShryku

Well, then obvious answer is "yes". It's just good coding to initialize your variables beforehand. Say you have a number variable that's going to continually get added to. Do you set $num=0; before adding to it? Or do you just start adding without setting an initial value?