PHP sort function (alphabetically)

Peter B

I have a PHP function which is supposed to say if one string is alphabetically before another.

function before($alpha,$beta)
{
	$arr = array(strtolower($alpha),strtolower($beta));
	sort($arr);
	if ($arr[0]==$alpha)
	{
		echo $alpha." before ".$beta."<br>";
		return true;
	} else {
		echo $alpha." after ".$beta."<br>";
		return false;
	}
}

However if I insert $alpha as "Apple" and $beta as "Cherry". It echos 'Apple after Cherry' and returns false.

How do I make this return the correct alphabetical order on these strings?

Ph3n0m

sorry you code is slightly wrong, you need to loop the array before you can use $arr[0]

the code should look like this

function before($alpha,$beta)
{
	$arr = array(strtolower($alpha),strtolower($beta));
	asort($arr);
foreach ($arr as $value) {
	if ($value=$alpha)
	{
		echo $alpha." before ".$beta."<br>";
		return true;
	} else {
		echo $alpha." after ".$beta."<br>";
		return false;
	}
    
}
}

seamus

Assuming that you're only taking two scalar string arguments as variables, it's much more efficient to just use strcmp to compare them

function before($alpha,$beta)
{
	if (strcasecmp($alpha, $beta) < 0)
	{
		echo $alpha." before ".$beta."<br>";
		return true;
	} else {
		echo $alpha." after ".$beta."<br>";
		return false;
	}
}

strcasecmp() is a case-insensitive comparision (removes the need for strtolower).
strcmp() is case-sensitive.

If you're going to use this function with user (or variable) input, then maybe check for special case. Off the top of my head, some of these are:
1. The empty string
2. All whitespace strings
3. The case where $alpha == $beta.

Liam Byrne

There are a couple of errors in that code, and both are in the initial comparison

"$arr[0]==$alpha"

1) The comparison is an "==", which checks if they are equal; it should be "<="
2) The comparison is using the original value of $alpha, rather than the post-strtolower entry of $beta in the array. As it is, the code is checking if $arr[0]==$alpha (and given the code, that's essentially checking if $alpha is lowercase).

The proper line (quick replacement of code) is

$arr[0]<=$arr[1]

As seamus said, though, you could avoid the array completely and use strcasecmp directly on $alpha and $beta, but try the above substitution first so that you're happy that the logic is working, before you go using a new function that you're not familiar with.