Explain the causes and solutions to the Warning: A non-numeric value encountered problem in PHP

This article introduces the Warning: A non-numeric value encountered problem in PHP. It uses examples to analyze the reasons for this error and provides methods to avoid and solve the problem.

<?phperror_reporting(E_ALL);
ini_set(&#39;display_errors&#39;, &#39;on&#39;);$a = &#39;123a&#39;;$b = &#39;b456&#39;;echo $a+$b;?>

After the above code is executed, it will prompt Warning: A non-numeric value encountered

Check the official PHP7.1 documentation for an explanation of this error

New E_WARNING and E_NOTICE errors have been introduced when invalid strings are coerced using operators expecting numbers ( - * / ** % << >> | & ^) or their assignment equivalents. An E_NOTICE is emitted when the string begins with a numeric value but contains trailing non-numeric characters, and an E_WARNING is emitted when the string does not contain a numeric value.

In use ( - * / * * % << >> | & ^) When operating, such as a b, if a starts a numeric value but contains non-numeric characters (123a), and b does not start a numeric value (b456), there will be A non-numeric value encountered warning.

Solution

For this kind of problem, you should first check the code logic to see why mixed values ​​appear and check where the error occurred. Resulting in mixed values.

For the operation of ( - * / ** % << >> | & ^), we can also add a conversion type method to convert the wrong value.

<?phperror_reporting(E_ALL);
ini_set(&#39;display_errors&#39;, &#39;on&#39;);$a = &#39;123a&#39;;$b = &#39;b456&#39;;echo intval($a)+intval($b);?>

After adding the intval method to force conversion to numeric type, the warning problem can be solved.

This article explains the reasons and solutions for the Warning: A non-numeric value encountered problem in PHP. For more related content, please pay attention to the PHP Chinese website.

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