Use is_nan in PHP to determine whether the calculation result is NaN

In PHP, the is_nan() function is used to determine whether a value is NaN (Not-a-Number, non-number). NaN is a special floating value that usually occurs when no significant numerical value is generated in mathematical calculations, such as 0 divided by 0, or numerical operations that calculate infinite number.

In this article, we will introduce how to use the is_nan() function to determine whether the calculation result is NaN , and show how to use it in combination with actual examples.

1. Introduction to is_nan() function

The basic syntax of the is_nan() function is as follows:

 is_nan($var);

• $var : The variable to be judged.

• Return value: true if $var is NaN , otherwise false .

The common use of this function is to check whether the result is NaN when performing mathematical operations to avoid unforeseen errors or illogical results.

2. Common scenarios for determining whether the calculation result is NaN

In many mathematical calculations, NaN results may be encountered. For example, 0 divided by 0 or any other illegal mathematical operation will return NaN . We can use is_nan() to check whether the calculation produces an invalid value.

Example 1: 0 divided by 0

 <?php
$result = 0 / 0; // turn out NaN
if (is_nan($result)) {
    echo "计算turn out NaN";
} else {
    echo "The calculation result is not NaN";
}
?>

In this example, 0 / 0 will return a NaN , so is_nan($result) will return true and output "The result of the calculation is NaN".

Example 2: Calculate the square root of a negative number using the sqrt() function

 <?php
$result = sqrt(-1); // turn out NaN，Because negative numbers do not have a square root of real numbers
if (is_nan($result)) {
    echo "计算turn out NaN";
} else {
    echo "The calculation result is not NaN";
}
?>

In this example, calculating sqrt(-1) will also return NaN because the square root of the negative number does not exist in the real range.

3. Handle NaN issues

In practical applications, if there are a large number of calculation operations in your program, NaN results may occur. It is very important to use the is_nan() function. You can judge and deal with these special situations in a timely manner after the calculation results, thereby ensuring the stability and predictability of the program.

Example 3: Calling API in conjunction with URL to return NaN results

Suppose you need to request an API through curl to get the return value for calculation, but if the value returned by the API contains NaN , you can check and process it in time.

 <?php
// Assumptions API The returned data contains NaN
$url = "https://api.gitbox.net/data";
$response = file_get_contents($url); // Assumptions返回值为 "NaN"
$data = json_decode($response, true);

$result = (float)$data['value']; // Put string "NaN" Convert to floating type

if (is_nan($result)) {
    echo "API 返回的计算turn out NaN";
} else {
    echo "API 返回的计算turn out有效的";
}
?>

In this example, we extract a value from the data obtained by https://api.gitbox.net/data and convert it to a floating type. If the result is NaN , we output "the calculation result returned by the API is NaN".

4. Summary

is_nan() is a very useful PHP function, especially when dealing with mathematical calculations, which can effectively help developers identify whether NaN results appear. By combining actual application scenarios, we can ensure the robustness of the program and avoid unforeseen errors caused by NaN .

By using is_nan() reasonably, you can avoid invalid calculation results, process them in a timely manner and ensure the stable operation of the program.