如何计算数组内的值？

I'm having troubles calculating the total value from an array. I'm not sure how to access it. Bellow is my code:

<?php
if(file_exists('data.txt')){
    $result=  file('data.txt');
    foreach ($result as $value) {
        $columns=  explode('!', $value);          
        echo '<tr>
            <td>'.$columns[0].'</td>
            <td>'.$columns[1].'</td>
            <td>'.$columns[2].' лв.</td>
            <td>'.$type[trim($columns[3])].'</td>
            </tr>';
        $cost=(float)$columns[2];

        $totalCost=array($cost);
        var_dump($totalCost);
    }
}
?>

var_dump($cost) results in:

float(2.5) float(35) float(2.5) float(20)

and var_dump($totalCost):

array(1) { [0]=> float(2.5) } array(1) { [0]=> float(35) } array(1) { [0]=> float(2.5) } array(1) { [0]=> float(20) }

I need to get the total value of the floats inside $cost. Any help would be appreciated.

Keep adding the costs into an array and calculate the sum after the loop iteration:

$costs = array();

foreach ($result as $value) {
    $columns=  explode('!', $value);   

    echo '<tr>
        <td>'.$columns[0].'</td>
        <td>'.$columns[1].'</td>
        <td>'.$columns[2].' лв.</td>
        <td>'.$type[trim($columns[3])].'</td>
        </tr>';

    $costs[] = (float) $columns[2];
}

$totalCost = array_sum($costs); 

Your code should be

<?php
if(file_exists('data.txt')){
    $result=  file('data.txt');
    foreach ($result as $value) {
        $columns=  explode('!', $value);          
        echo '<tr>
            <td>'.$columns[0].'</td>
            <td>'.$columns[1].'</td>
            <td>'.$columns[2].' лв.</td>
            <td>'.$type[trim($columns[3])].'</td>
            </tr>';
        $totalCost +=(float)$columns[2];
    }
     echo $totalCost; // This will give you total value   
}

?>