is_infinite
For seeing whether or not something is a number, use ctype_digit().
is_nan
(PHP 4 >= 4.2.0, PHP 5)
is_nan — 값이 수가 아닌지 확인합니다
설명
bool is_nan
( float $val
)
val 이 '숫자가 아닌'지 확인합니다. acos(1.01)의 결과 등은 숫자가 아닙니다.
인수
- val
-
확인할 값
반환값
val 이 '숫자가 아닐' 경우 TRUE, 아니면 FALSE를 반환합니다.
예제
Example #1 is_nan() 예제
// NaN을 반환하는
// 잘못된 계산
$nan = acos(8);
var_dump($nan, is_nan($nan));
?>
위 예제의 출력:
float(NaN) bool(true)
참고
- in_finite()
- in_infinite()
add a note
User Contributed Notesis_nan
darkangel at moveinmod dot net
02-Mar-2006 03:04
02-Mar-2006 03:04
nan/"not a number" is not meant to see if the data type is numeric/textual/etc..
NaN is actually a set of values which can be stored in floating-point variables, but dont actually evaluate to a proper floating point number.
The floating point system has three sections: 1 bit for the sign (+/-), an 8 bit exponent, and a 23 bit fractional part.
There are rules governing which combinations of values can be placed into each section, and some values are reserved for numbers such as infinity. This leads to certain combinations being invalid, or in other words, not a number.
Sku
04-Dec-2005 06:29
04-Dec-2005 06:29
Hi nez,
better would be:
function isNaN( $var ) {
return !ereg ("^[-]?[0-9]+([\.][0-9]+)?$", $var);
}
ys, Sku
nez [at] NOSPAM gazeta [dot] pl
27-Sep-2005 05:27
27-Sep-2005 05:27
Paul, i guess better would be:
function isNaN( $var ) {
return ereg ("^[-]?[0-9]+([\.][0-9]+)?$", $var);
}
Vincent
24-Feb-2005 11:04
24-Feb-2005 11:04
Since NaN is not even equal to itself, here is a way to test it:
<?php
function my_is_nan($_) {
return ($_ !== $_);
}
?>