验证引擎将负数转换为正数

Question

how can I enter only positive number and if I entered negative number it will convert automatically to positive number this the code That I have how can I edit it

<?php
    if (isset($_SESSION["cart_products"]) && count($_SESSION["cart_products"]) > 0) {
        echo '<div class="cart-view-table-front" id="view-cart">';
        echo '<h3>Your Shopping Cart</h3>';
        echo '<form method="post" action="cart_update.php">';
        echo '<table width="100%"  cellpadding="6" cellspacing="0">';
        echo '<tbody>';

        $total = 0;
        $b = 0;
        foreach ($_SESSION["cart_products"] as $cart_itm) {
            $product_name = $cart_itm["product_name"];
            $product_qty = $cart_itm["product_qty"];
            $product_price = $cart_itm["product_price"];
            $product_code = $cart_itm["product_code"];
            $product_color = $cart_itm["product_color"];
            $bg_color = ($b++ % 2 == 1) ? 'odd' : 'even'; //zebra stripe
            echo '<tr class="' . $bg_color . '">';
            echo '<td>Qty <input type="text" size="3" maxlength="3" name="product_qty[' . $product_code . ']" value="' . $product_qty . '"  /></td>';
            echo '<td>' . $product_name . '</td>';
            echo '<td><input type="checkbox" name="remove_code[]" value="' . $product_code . '" /> Remove</td>';
            echo '</tr>';
            $subtotal = ($product_price * $product_qty);
            $total = ($total + $subtotal);
        }
        echo '<td colspan="4">';
        echo '<button type="submit">Update</button><a href="view_cart.php" class="button">Checkout</a>';
        echo '</td>';
        echo '</tbody>';
        echo '</table>';

        $current_url = urlencode($url = "http://" . $_SERVER['HTTP_HOST'] .     $_SERVER['REQUEST_URI']);
        echo '<input type="hidden" name="return_url" value="' .     $current_url . '" />';
        echo '</form>';
        echo '</div>';
    }
    ?>

Answer 1

GrumpyCrouton > What is the variable that you are trying to convert to positive?

M.Alhaddad > @GrumpyCrouton product_qty

It's quite simple.

Just use abs() on the variable.

$product_qty = abs($cart_itm["product_qty"]);

Note: abs() works in (PHP 4, PHP 5, PHP 7)

"Converting a number to positive" is just getting it's absolute value.

Documentation: PHP function.abs