PHP: Confused about FOR loops and 2 brackets

Question

just a question about the following loop and the brackets at the end (i just started learning PHP so its likely a noob question). i wrote the following code and it didnt work:

        <?php 
        function maximum(){
        $wieviele = func_num_args();
        $arg = func_get_args();
        $first = $arg[0];

        for ($i = 1;$i < $wieviele;$i++){
        if ($first < $arg[$i])
        $first = $arg[$i];

        return $first;
        }


        }

        echo maximum(1,4,64,9);
        ?>

Now i checked it out in the book i'm reading and the solution is the following code which is nearly equal except the brackets at the end.

        <?php 
        function maximum(){
        $wieviele = func_num_args();
        $arg = func_get_args();
        $first = $arg[0];

        for ($i = 1;$i < $wieviele;$i++)
        if ($first < $arg[$i])
        $first = $arg[$i];

        return $first;



        }

        echo maximum(1,4,64,9);
        ?>

And now i would love to know why it only works without the brackets for the FOR-loop.

Thank you

Answer 1

When you have a control structure such as a for loop or an if statement and you don't include a set of brackets after it, only the next line is considered to be inside the control structure.

So when you have

    for ($i = 1;$i < $wieviele;$i++)
    if ($first < $arg[$i])
    $first = $arg[$i];

    return $first;

It means

    for ($i = 1;$i < $wieviele;$i++){
        if ($first < $arg[$i]){
            $first = $arg[$i];
        }
    }
    return $first;

That is, it sets $first equal to $arg[$i] when appropriate and returns once the loop is finished.

In your code, you have

    for ($i = 1;$i < $wieviele;$i++){
    if ($first < $arg[$i])
    $first = $arg[$i];

    return $first;
    }

Which is equivalent to

    for ($i = 1;$i < $wieviele;$i++){
        if ($first < $arg[$i]){
            $first = $arg[$i];
        }
        return $first;
    }

So you'll enter the first iteration of the loop, check the condition, and then return $first. That is, you return after the first iteration, not when the loop is complete.

My advice concerning omitting/including brackets is to always be as explicit as you can, to make the purpose and effect of your code as intuitive as possible.

Answer 2

You need to add return $first; outside of your for loop on your first code block to make it work properly.

Demonstration

The first code didn't work because you were returning the value prematurely

---

Why not make it simpler ?

Use max() instead...

$array = array(1,4,64,9); //<--- Add elements to your array
echo max($array); // 64

Answer 3

It is reccommended to use bracket even for one line body of loops.if-statemnts.

Equivalent with bracets of this code

for ($i = 1;$i < $wieviele;$i++)
if ($first < $arg[$i])
$first = $arg[$i];

is

for ($i = 1;$i < $wieviele;$i++)
{
    if ($first < $arg[$i])
    {
        $first = $arg[$i];
    }
}