How does PHP determine the type of a value (finite, infinite or non-numeric)?

Given any numerical value, it can be classified into 3 different categories such as finite value, infinite value and non-numeric value (commonly known as NaN). So how to use PHP to quickly judge? The following article will introduce to you the method of judging the numerical type (finite value, infinite value or non-value). I hope it will be helpful to you.

In PHP we can use the is_finite() function to judge finite values, the is_infinite() function to judge infinite values, and the is_nan() function to judge non-numeric values; let’s learn about it below Take a look at these functions. [Video tutorial recommendation: PHP tutorial]

PHP is_finite() function

is_finite() function can determine a Whether the value is a finite value. This function returns true if the specified value is a finite value; otherwise, it returns false.

Note: A value is finite if it is within the range allowed by PHP floating point numbers on the native platform.

Example:

<?php 
header("content-type:text/html;charset=utf-8");
$Array = array( "M_PI"=>M_PI,"INF"=>INF,"a"=>5214853545); 
var_dump($Array); 
foreach($Array as $k => $val) { 
    if(is_finite($val)) { 
    echo $k." =".$val."是有限值<br>";
    } 
else{
echo $k." =".$val."是不有限值<br>";
}
}                       
?>

Output:

Explanation: M_PI and INF are PHP 5 predefined Math constants, and M_PI has a limited values, INF is infinite.

PHP is_infinite() function

The is_infinite() function can determine whether a value is infinite. If the specified value is infinite, the function returns TRUE; otherwise, it returns FALSE.

Note: If the value is not within the range allowed by PHP floating point numbers on the native platform, the value is infinite.

Example:

<?php 
header("content-type:text/html;charset=utf-8");
$Array = array( "log(0)"=>log(0),"log(1)"=>log(1),"INF"=>INF,"a"=>5214853545); 
var_dump($Array); 
foreach($Array as $k => $val) { 
    if(is_infinite($val)) { 
    echo $k." =".$val."是无限值<br>";
    } 
else{
echo $k." =".$val."不是无限值<br>";
}
}                       
?>

Output:

##PHP is_nan() function

The is_nan() function can determine whether a value is non-numeric. This function returns true if the specified value is non-numeric; otherwise, it returns false.

Example:

<?php 
header("content-type:text/html;charset=utf-8");
$Array = array( "log(0)"=>log(0),"log(1)"=>log(1),"acos(-1.01)"=>acos(-1.01)); 
var_dump($Array); 
foreach($Array as $k => $val) { 
    if(is_nan($val)) { 
    echo $k." =".$val."是非数值<br>";
    } 
else{
echo $k." =".$val."不是非数值<br>";
}
}                       
?>

Output:

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