Using a for loop to replace if statement

Question

I'm trying to figure out how to use a for loop to cycle though an array and test for two conditions. I've done it with a foreach loop, but trying to get it done with a for loop. Below is the if block and for loop that I've been working on.

        if (empty($scores[0]) ||
        empty($scores[1]) ||
        empty($scores[2]) ||
        !is_numeric($scores[0]) ||
        !is_numeric($scores[1]) ||
        !is_numeric($scores[2])) {
            $scores_string = 'You must enter three valid numbers for scores.';
            break;
    }

Here is the HTML and PHP.

HTML:

<form action="." method="post">
    <input type="hidden" name="action" value="process_scores" />

    <label>Choose action:</label><br />
    <input class="radio" type="radio" name="calculate" value="average" checked="checked">Average<br />
    <input class="radio" type="radio" name="calculate" value="total">Total<br />
    <input class="radio" type="radio" name="calculate" value="both">Both<br />

    <label>Score 1:</label>
    <input type="text" name="scores[]"
           value="<?php echo $scores[0]; ?>"/><br />

    <label>Score 2:</label>
    <input type="text" name="scores[]"
           value="<?php echo $scores[1]; ?>"/><br />

    <label>Score 3:</label>
    <input type="text" name="scores[]"
           value="<?php echo $scores[2]; ?>"/><br />

    <label>&nbsp;</label>
    <input type="submit" value="Process Scores" /><br />

    <label>Scores:</label>
    <span><?php echo $scores_string; ?></span><br />

    <label>Score Total:</label>
    <span><?php echo $score_total; ?></span><br />

    <label>Average Score:</label>
    <span><?php echo $score_average; ?></span><br />
</form>

PHP:

if (isset($_POST['action'])) {
$action =  $_POST['action'];
} else {
$action =  'start_app';
}

switch ($action) {
case 'start_app':
    $scores = array();
    $scores[0] = 70;
    $scores[1] = 80;
    $scores[2] = 90;
    break;
case 'process_scores':
    $scores = $_POST['scores'];


    // validate the scores
    for ($i = 0; $i < count($scores); $i++) {
        if (empty($scores[$i]) || !is_numeric($scores[$i])) {
        $scores_string = 'You must enter three valid numbers for scores.';
        break;
        }
    }


    // process the scores
    $scores_string = '';
    foreach ($scores as $s) {
        $scores_string .= $s . '|';
    }
    $scores_string = substr($scores_string, 0, strlen($scores_string)-1);

    // Radio buttons
    $calculate_type = $_POST['calculate'];

    switch ($calculate_type) {
        case 'average':
            $score_tally = $scores[0] + $scores[1] + $scores[2];
            $score_average = $score_tally / count($scores);
            $score_average = number_format($score_average, 2);
            break;
        case 'total':
            $score_total = $scores[0] + $scores[1] + $scores[2];
            $score_total = number_format($score_total, 2);              
            break;
        case 'both':
            $score_tally = $scores[0] + $scores[1] + $scores[2];
            $score_average = $score_tally / count($scores);
            $score_total = $scores[0] + $scores[1] + $scores[2];
            $score_total = number_format($score_total, 2);
            $score_average = number_format($score_average, 2);
            break;
    }

    break;
case 'process_rolls':
    $number_to_roll = $_POST['number_to_roll'];

    $total = 0;
    // $count = 0;
    $max_rolls = -INF;

    for ($count = 0; $count < 1000; $count++) {
        $rolls = 1;
        while (mt_rand(1, 6) != 6) {
            $rolls++;
        }
        $total += $rolls;
        $max_rolls = max($rolls, $max_rolls);
    }
    $average_rolls = $total / $count;

    break;


}

With this for loop under validate the scores in place, I yield no results when there is invalid data.

Niet the Dark Absol · Accepted Answer · 2013-10-06 00:08:11Z

2

I would take a look at array_reduce, since that's basically what you're doing: Reducing an array to a boolean.

if( array_reduce(
   $scores,
   function($a,$b) {return $a || empty($b) || !is_numeric($b);},
   false)) {
       $scores_string = "You must enter three valid numbers for scores.";
}

answered Oct 6, 2013 at 0:08

Niet the Dark Absol

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2 Comments

user924016 Over a year ago

"{return $a || empty($b) || !is_numeric($b);}" how does that work?

geomagas Over a year ago

array_reduce() will iterate all elements. $a is a copy of the cumulative result from previous iterations (an internal variable in array_reduce()). The function parameter is supposed to update it for the current iteration ($b is the current element) and return the new, updated value.

geomagas · Accepted Answer · 2013-10-06 00:14:34Z

2

Since you asked for a for loop:

for ($i = 0; $i < count($scores); $i++)
    if (empty($scores[$i]) || !is_numeric($scores[$i])) {
        $scores_string = 'You must enter three valid numbers for scores.';
        break;
    }

answered Oct 6, 2013 at 0:14

geomagas

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5 Comments

user1890525 Over a year ago

I've tried your example and I get nothing. The scores are being populated by user input. All text fields share the same name attribute "scores[]". I used $scores = $_POST['scores'] to obtain the user entries. As of now with your example in place, I get no error message indicating an empty or invalid number.

geomagas Over a year ago

I'm a bit confused. You mean you get no error message where you should? Or that you get no output using correct data? If it's the former, please check the condition inside if. If it's the latter, then yes, that's supposed to be working.

user1890525 Over a year ago

Correct! I should receive the $scores_string when the input field is blank or isNAN. Using the if block I posted above works fine, so I know there isn't a problem with the $scores_string.

geomagas Over a year ago

You actually do receive it. You just make it '' (ie an empty string) right after the loop, using $scores_string = '';,so that setting it to the error message becomes useless...

geomagas Over a year ago

You're welcome. Oh, and if my answer helped you solve your problem, please consider accepting it.

ofca · Accepted Answer · 2013-10-06 12:34:19Z

1

I don't understand why you testing if score is emtpy. If score is empty then is_numeric return false.

My version of for loop:

for ($i = 0, $len = count($scores); $i < $len and is_numeric($scores[$i]); $i++) {}
if ($i !== $len) echo 'You must enter three valid numbers for scores.';

edit: If you need to test if there are exactly 3 numeric items in array (as @geomagas suggest) then:

for ($i = 0; $i < 3 and is_numeric($scores[$i]); $i++) {}

// If $i is less then 3 it's mean that one of items are not set or it's not numeric
if ($i < 3) echo 'You must enter three valid numbers for scores.';

edit: Third solution which handle situation when array is not properly indexed. I'm posting this just for fun, refusing to use empty function which @geomagas forcing on me ;)

$scores = array('234', '52', '245');

for (reset($scores); $valid = is_numeric(current($scores)) and next($scores);) {}

if ( ! $valid) echo 'You must enter three valid number for scores.';

edited Oct 6, 2013 at 12:34

answered Oct 6, 2013 at 0:37

ofca

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8 Comments

geomagas Over a year ago

Please see my comment to abstr's answer, I think it applies to yours as well.

geomagas Over a year ago

No, no, I didn't mean that. I was thinking towards the possibility of replacing empty() with isset() rather than eliminating it. What if $scores looks like this: Array([0]=>4,[2]=>9)? NOTE: I still think this is not relevant to the question.

ofca Over a year ago

If it will be Array([0]=>4,[2]=>9) then $i from my second example will be equal 2 and validation error will be shown. isset/empty it not necessary here.

geomagas Over a year ago

No it wouldn't. Take a step back and think. Would execution get past your for loop? Or would php bail out spitting an error? Did you even try your own suggestion?

ofca Over a year ago

I assume that array is properly indexed and there is no missing "1" index. Otherwise I suggest to use foreach with if statement.

|

abstr · Accepted Answer · 2013-10-06 00:54:53Z

0

empty() should not be used since 0 is considered to be empty as well as is numeric.

$size = count($scores);
for ($i = 0; $i < $size; $i++) {
    if (!is_numeric($scores[$i])) {
        $scores_string = 'You must enter three valid numbers for scores.';
        break;
    }
}

answered Oct 6, 2013 at 0:54

abstr

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7 Comments

geomagas Over a year ago

Almost a good point, although that wasn't part of the question. But does is_numeric test if a variable is set?

abstr Over a year ago

$scores[$i] is always set, since the for loop counted the array size prior to usage.

geomagas Over a year ago

Playing the devil's advocate, suppose $scores is Array([0]=>4,[2]=>9,[5]=>12). See also: Comments on ofca's answer

abstr Over a year ago

hmm.. then $scores = array_values($scores) will do it. But @geomagas aren't we hijacking @user1890525's question? :)

geomagas Over a year ago

+1: Yes you're right. In both your points. From my side, for all it's worth, I consider the answer improved (by you, I mean). Thank you for responding to my argument.

|

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