PHP Notice: A non well formed numeric value encountered - Solution

PHP Notice: A non well formed numeric value encountered - Solution

During the development process using PHP, you often encounter some warning and error messages. One of the common warnings is "Notice: A non well formed numeric value encountered". This warning usually appears when trying to convert a string to a numeric value. In this article, we will understand why this warning appears and provide some solutions.

This warning usually appears in the following situations:

1. When performing mathematical operations, strings are used as numerical values.
2. When trying to convert a human-readable time format to a timestamp.
3. When trying to convert a string containing non-numeric characters to an integer or floating point number.

Here are some common code examples and workarounds:

1. Use strings as numeric values ​​when performing math operations

$num1 = "10";
$num2 = "5";

// 错误示例
$result = $num1 + $num2;

// 正确示例
$result = intval($num1) + intval($num2);

In the error example, we use the strings $num1 and $num2 as numerical values ​​to perform addition operations. Since PHP is a weakly typed language, it attempts to convert strings to numeric values. However, if the string is not in a legal numeric format, a warning will appear. To solve this problem, we can use the intval() function to convert the string to an integer.

2. When trying to convert a human readable time format to a timestamp

$dateString = "2021-01-15";

// 错误示例
$timestamp = strtotime($dateString);

// 正确示例
$timestamp = strtotime("$dateString 00:00:00");

In the error example we are passing a date string to strtotime() function to convert it to a timestamp. However, since the date string does not contain specific time information, PHP will try to convert it to a timestamp of the current time. As a result, the result is not a valid timestamp and a warning will appear. In order to solve this problem, we can add specific time information after the date string to make it a complete date and time string.

3. When trying to convert a string containing non-numeric characters to an integer or floating point number

$numberString = "123abc";

// 错误示例
$number = intval($numberString);

// 正确示例
$number = preg_replace("/[^0-9]/", "", $numberString);

In the error example, we try to convert a string containing non-numeric characters to an integer or floating point number. Convert the string to an integer. Because the string contains non-numeric characters, PHP cannot parse it as a number, and a warning appears. To solve this problem, we can use the preg_replace() function to replace non-numeric characters with an empty string.

Summary:

The warning message "Notice: A non well formed numeric value encountered" is one of the common errors in PHP development. By understanding several common situations that cause this warning and providing corresponding solutions, we can avoid this error and write more robust code. When converting a string into a numerical value, we need to ensure that the input string is in a legal numerical format, or use the corresponding function to convert and process it to avoid warnings.

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