Warning: a Non-Numeric Value Encountered

Not exactly the issue you had but the same error for people searching.

This happened to me when I spent too much time on JavaScript.

Coming back to PHP I concatenated two strings with + instead of . and got that error.

You can solve the problem without any new logic by just casting the thing into the number, which prevents the warning and is equivalent to the behavior in PHP 7.0 and below:

$sub_total += ((int)$item['quantity'] * (int)$product['price']);

(The answer from Daniel Schroeder is not equivalent because $sub_total would remain unset if non-numeric values are encountered. For example, if you print out $sub_total, you would get an empty string, which is probably wrong in an invoice. - by casting you make sure that $sub_total is an integer.)

In my case it was because of me used + as in other language but in PHP strings concatenation operator is ..

Hello, In my case using (WordPress) and PHP7.4 I get a warning about numeric value issue. So I changed the old code as follow:

From:

$val = $oldval + $val;

To:

$val = ((int)$oldval + (int)$val);

Now the warning disappeared :)

I had this issue with my pagination forward and backward link .... simply set (int ) in front of the variable $Page+1 and it worked...

<?php 
$Page = (isset($_GET['Page']) ? $_GET['Page'] : '');
if ((int)$Page+1<=$PostPagination) {
?>
<li> <a href="Index.php?Page=<?php echo $Page+1; ?>"> &raquo;</a></li>
<?php }
?>

This was happening to me specifically on PHPMyAdmin. So to more specifically answer this, I did the following:

In File:

C:\ampps\phpMyAdmin\libraries\DisplayResults.class.php

I changed this:

// Move to the next page or to the last one
$endpos = $_SESSION['tmpval']['pos']
    + $_SESSION['tmpval']['max_rows'];

To this:

$endpos = 0;
if (!empty($_SESSION['tmpval']['pos']) && is_numeric($_SESSION['tmpval']['pos'])) {
    $endpos += $_SESSION['tmpval']['pos'];
}
if (!empty($_SESSION['tmpval']['max_rows']) && is_numeric($_SESSION['tmpval']['max_rows'])) {
    $endpos += $_SESSION['tmpval']['max_rows'];
}

Hope that save's someone some trouble...

I encountered the issue in phpmyadmin with PHP 7.3. Thanks @coderama, I changed libraries/DisplayResults.class.php line 855 from

// Move to the next page or to the last one
$endpos = $_SESSION['tmpval']['pos']
    + $_SESSION['tmpval']['max_rows'];

into

// Move to the next page or to the last one
$endpos = (int)$_SESSION['tmpval']['pos']
    + (int)$_SESSION['tmpval']['max_rows'];

Fixed.

Try this.

$sub_total = 0;

and within your loop now you can use this

$sub_total += ($item['quantity'] * $product['price']);

It should solve your problem.

Check if you're not incrementing with some variable that its value is an empty string like ''.

Example:

$total = '';
$integers = range(1, 5);

foreach($integers as $integer) {
    $total += $integer;
}

PHP 7.1-7.4

This warning happens when you have a non-numeric string in an expression (probably +, -, *, or /) where PHP is expecting to see another scalar (int, float, or bool). There are two likely situations where this happens:

• You did not mean to use an operation that expects a scalar. For example, + (addition) when you meant . (concatenation).
• You were expecting a number, but the value you used was not even close to a number. Figure out what your non-number is, and handle accordingly.
  • For example, if you have echo 3 + $variable and your $variable is the string "n/a", then you might decide to instead echo "not applicable". Or maybe you decide that all non-numeric values should be treated as 0 and cast to the .

Fix these warnings! In PHP 8, this becomes a fatal error: "Uncaught TypeError: Unsupported operand types".