looping issue with array

Question

    <?php
?>
<html>
    <head>
        <style>
            table {
                font-family: arial, sans-serif;
                border-collapse: collapse;
                width: 100%;
            }
            td, th {
                border: 1px solid #dddddd;
                text-align: left;
                padding: 8px;
            }
            tr:nth-child(even) {
                background-color: #dddddd;
            }
        </style>
    </head>
    <body>
        <table>
            <thead>
                <tr>
                    <th>
                    </th>
                    <?php
for($i = 1; $i <=31;$i++){
    echo '<th>'.$i.'</th>';
}
                    ?>
                </tr>
            </thead>
            <tbody>
                <td>
                    Item A
                </td>
                <?php 
$qty_n_day = '1/2,3/6';
$qty_day = explode(',',  $qty_n_day);
foreach ($qty_day as $qd) {
    list($qty,$day) = explode('/', $qd);
    for($i = 1; $i <=31;$i++){
        if($day == $i)
            echo '<td>'.$qty.'</td>';
        else
            echo '<td>-</td>';
    }
}
                ?>
            </tbody>
        </table>
    </body>
</html>

Output result My expected result

The 31 column indicate as days.
I stored quantity and days together, and then extract it after into a list.
After that, i want to compare it with day column and show qty value for the column.

How can i do that? Is my logic wrong?

Your foreach is looping over two items, in there you're looping over 31 days. So you're generating 62 <td>s. — rickdenhaan
– rickdenhaan, Commented Dec 28, 2017 at 14:03
Design wise, I would consider maybe loading this into an associative array. Then you can display the chart with the array and using key=>value pairs and you can also easily manipulate the data. Using a for loop to print the data works fine but a foreach loop would probably be more straightforward. Also your use of strings to pair quantity with day could also be solved with something such as an associative array, which is ultimately what you get when you explode the data but still this is sort of confusing and hard to grasp from a glance. Assoc. array is designed for tasks like these. — cchoe1
– cchoe1, Commented Dec 28, 2017 at 14:04

Claudio · Accepted Answer · 2017-12-28 14:07:20Z

3

Try this way, creating an associative array first with the day and value:

<?php 
    $qty_n_day = '1/2,3/6';
    $qty_day = explode(',',  $qty_n_day);

    $days = [];
    foreach ($qty_day as $day) {
        if (($res = explode('/', $day))) {
            $days[$res[1]] = $res[0];
        }
    }
    /*
    the array should stay like this
    $days = [
        2 => 1,
        6 => 3
    ];
    */

    for($i = 1; $i<=31;$i++){ 
        if (isset($days[$i])) { // if the key exists set the value
            echo '<td>' . $days[$i] . '</td>';
        } else {
            echo '<td>-</td>';
        }
    }

?>

answered Dec 28, 2017 at 14:07

Claudio

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Comments

Philipp Maurer · Accepted Answer · 2017-12-28 14:08:08Z

1

You have to change the order of your loops: Your foreach loop loops through the quantities and contains the for loop, that loops through the days. This leads to the behavior, that the for loop runs completely through for each quantity, therefore echoing 31 days. This means that for 2 quantities 62 days are printed.

You need to flip the loops and add a conditional output to them:

for ($i = 1; $i <= 31; $i++) {
    $quantity = '-';
    foreach ($qty_day as $qd) {
        list($qty,$day) = explode('/', $qd);
        if ($day == $i) {
            $quantity = $qty;
            break;
        }
    }
    echo '<td>' . $quantity . '</td>';
}

answered Dec 28, 2017 at 14:08

Philipp Maurer

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Comments

Tommaso Belluzzo · Accepted Answer · 2017-12-28 14:21:25Z

1

The problem arises from the fact that you are performing two iterations, the first one processing 2 cycles and the second one processing 31 cycles... for a total of 62 elements being generated.

I propose you a much more compact solution, that builds up the final array first and then simply prints it:

<?php 

    $arr = array_fill(1, 31, "-");

    $qty_n_day = '1/2,3/6';
    $qty_day = explode(',',  $qty_n_day);

    foreach ($qty_day as $qd)
    {
        list($qty,$day) = explode('/', $qd);
        $arr[$day] = $qty;
    }

    for ($i = 1; $i <= 31; ++$i)
    {
        echo '<td>'.$arr[$i].'</td>';
    }

?>

answered Dec 28, 2017 at 14:21

Tommaso Belluzzo

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