How to solve “undefined variable : total” in php?

Question

I'm just new here in php and im trying to create a simple shopping cart..but every time i run the code, an error occurred. it said "Notice: Undefined variable: total in C:\\wamp\\www\\irm\\cart.php on line 372". Here's my code:

function cart(){
  echo "<table  table border='1' cellpadding='10'>"; 
  foreach($_SESSION as $name`` => $value){
    if ($value>0){

        if(substr($name, 0, 5)=='cart_'){
            $id = substr($name, 5, (strlen($name)-5)); 
            $get = mysql_query('SELECT  prod_id, prod_name, prod_price FROM products WHERE prod_id='.mysql_real_escape_string((int)$id));
            while ($get_row = mysql_fetch_assoc($get)){
            $sub = $get_row['prod_price']*$value;

            echo "<tr><th>Product Name</th> <th>Quantity</th> <th>Price</th> <th>Total</th> <th>Increase</th> <th>Decrease</th> <th>Remove</th></tr>"; 
                echo '<td>'.$get_row['prod_name'].'</td>';
                echo '<td>'.$value.'</td>';
                echo '<td>'.' PhP'.number_format($get_row['prod_price'], 2).'</td>';
                echo '<td>'.' PhP'.number_format($sub,  2).'</td>';
                echo '<td>'.'<a href="cart.php?remove='.$id.'">[-]</a>'.'</td>';
                echo '<td>'.'<a href="cart.php?add='.$id.'">[+]</a>'.'</td>';
                echo '<td>'.'<a href="cart.php?delete='.$id.'">[Delete]</a></td>';

            }
        }
        $total += $sub;
    }
}
if($total==0){
    echo "Your cart is empty.";
}
else{
    echo 'Total: PhP'.number_format($total, 2);
}

Answer 1

This is because you don't define it before you use it. Declare it with a value of zero at the top of your function so it is always defined:

function cart(){
    $total = 0; // <-- what you need to add

Answer 2

声明变量并初始分配值0或使用isset()检查变量是否已设置

Answer 3

You must initialize $total before you can use it in an expression. You can initialize it like this:

$total = null;

Also Your code is missing the closing curly brace. You also have back ticks that should not be present:

$_SESSION as $name`` => $value

Answer 4

You will have to define the variable $total within the function and it give it a zero value.

function cart() {
    $total = 0;

    /* ... */
}