John Davidson

Message:

I have a text file with cities and population and a php program that should read the text file and insert the text into array while taking into account that the city should be key and the population is value of the array and the program has to sort the array by the value and to print its keys and values in table format.

Example data:

Tokyo   39105000

Jakarta 35362000

Delhi   31870000

Manila  23971000

Sao Paulo   22495000

Seoul   22394000

Mumbai  22186000

Shanghai    22118000

Mexico City 21505000

Guangzhou   21489000

This is the code:

    <?php

    $fileHandler = fopen("Info_array.txt", "rb");

    $data = [];



    while (!feof($fileHandler) ) {

        // read file row

        $row = fgets($fileHandler);



        $index = count($data);



        // explode array by space

        $data[$index] = explode(' ', $row);



        // explode data[$index][0] by '.', then insert into array in index 0 & 1

        array_splice($data[$index], 0, 1, explode('.', $data[$index][0]));

    }



    // sort array by array index 1

    usort($data, function ($prev, $next) {

        if ($prev[1] == $next[1]) {

            return 0;

        }



        return ($prev[1] < $next[1]) ? -1 : 1;

    });



    fclose($fileHandler);

?>



<table class="heavyTable">

    <thead>

        <tr>

            <th>City</th>

            <th>Population</th>

        </tr>

    </thead>

    <tbody>

        <?php foreach ($data as $item): ?>

            <tr>

                <td><?= $item[0] . '.' . $item[1] ?></td>

                <td><?= $item[2] ?></td>

                <td><?= $item[1] ?></td>

            </tr>

        <?php endforeach; ?>

    </tbody>

  </table>

I currently get error:

Warning: Undefined array key 1 in C:\xampp\htdocs\phpexercise.php on line 20



Warning: Undefined array key 1 in C:\xampp\htdocs\phpexercise.php on line 20



Warning: Undefined array key 1 in C:\xampp\htdocs\phpexercise.php on line 20



Warning: Undefined array key 1 in C:\xampp\htdocs\phpexercise.php on line 20

Any advices on how to do this will be very much appreciated, i'm struggling from a few days now.

---

My Answer:
// Read the text file
$file = fopen("cities.txt", "r");
$data = array();

// Insert text into array
while (!feof($file)) {
$line = fgets($file);
$city_population = explode(" ", $line);
$city = $city_population[0];
$population = intval($city_population[1]);
$data[$city] = $population;
}

// Sort the array by value
arsort($data);

// Print keys and values in table format
echo "";
echo "";
foreach ($data as $city => $population) {
echo "";
}
echo "

City	Population
$city	$population

";
fclose($file);
?>