PHP function application to check whether a value is finite, infinite or non-numeric

In the previous article "PHP function application: start executing the program after pausing for a few seconds", we learned about the method of delaying the execution of the current script to a specified time (how many seconds later). This time we continue to learn PHP functions and introduce how to check whether a given value is a finite value, an infinite value or a non-numeric value. Interested friends can learn about it~

The main point of this article The content is: Check whether a value is finite, infinite or non-numeric.

1: Check whether a value is a finite value

You can use the is_finite($value) function to determine a valuevalueWhether it is a limited value. If the specified value is a finite value, the function returns true or 1; otherwise, it returns false/nothing. A value is finite if it is within the range allowed by PHP floating point numbers on the native platform.

Let’s take a closer look at the following example:

<?php
header("content-type:text/html;charset=utf-8");
function isFinite($value){
	if(is_finite($value)){
		echo $value."是有限值。<br>";
	}else{
		echo $value."不是有限值。<br>";
	}
}
isFinite(2);
isFinite(log(0));
?>

log(0)The value is -INF, INF refers to infinity, And -INF is negative infinity; therefore log(0) is not a finite value. Therefore the output result:

Two: Check whether a value is infinite

You can use is_infinite($value) Function to determine whether a value value is infinite. If the specified value is a finite value, the function returns TRUE or 1; otherwise, it returns FALSE (no output). The value is infinite if it is within the range allowed by PHP floating point numbers on the native platform.

Let’s take a look at the following example in detail:

<?php
header("content-type:text/html;charset=utf-8");
function isInfinite($value){
	if(is_infinite($value)){
		echo $value."是无限值。<br>";
	}else{
		echo $value."不是无限值。<br>";
	}
}
isInfinite(2);
isInfinite(log(0));
?>

Output result:

Three: Check whether a value is Non-numeric

You can use the is_nan($value) function to determine whether a value is non-numeric. If the specified value is non-numeric, the function returns true or 1; otherwise, it returns false/nothing.

Let’s take a closer look at the following example:

<?php
header("content-type:text/html;charset=utf-8");
function isNan($value){
	if(is_nan($value)){
		echo "是非数值。<br>";
	}else{
		echo "不是非数值。<br>";
	}
}
isNan(2);
isNan(NAN);
isNan(acos(1.01));
?>

NaN (Not a Number, not a number) is a type of value of numeric data type in computer science, which represents undefined or unrepresentable value. Often used in floating point operations. We can use the is_nan() function to check if a value is NaN.

In the above example , acos(1.01) will return NaN, so the calculation result of acos(1.01) is a non-numeric value. Therefore, the output result is:

Okay, that’s all. If you want to know anything else, you can click this. → →php video tutorial

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