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PHP - Manual: gmp_sign

2024-12-23

gmp_sign

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gmp_signSign of number

说明

gmp_sign(GMP|int|string $num): int

Checks the sign of a number.

参数

num

Either a GMP object, or a numeric string provided that it is possible to convert the latter to an int.

返回值

Returns 1 if num is positive, -1 if num is negative, and 0 if num is zero.

范例

示例 #1 gmp_sign() example

<?php
// positive
echo gmp_sign("500") . "\n";

// negative
echo gmp_sign("-500") . "\n";

// zero
echo gmp_sign("0") . "\n";
?>

以上例程会输出:

1
-1
0

参见

add a noteadd a note

User Contributed Notes 7 notes

up
10
Andrew Martin
4 years ago
Using a spaceship in PHP7:

<?php
$sign
= $number <=> 0;
?>
up
19
thomas at zilliox dot me
10 years ago
Hi !

If you don't have the GMP extension, the sign function is really simple to code.
Here an example of implementation :

<?php
function sign( $number ) {
    return (
$number > 0 ) ? 1 : ( ( $number < 0 ) ? -1 : 0 );
}

echo
sign( 500 ); // Return 1
echo sign( -500 ); // Return -1
echo sign( 0 ); // Return 0
?>

Thomas.
up
-1
web-develop at yandex dot ru
6 years ago
Just
$sign = ($a==0 ?0 :$a/abs($a));
up
-4
jdyerjdyer
6 years ago
For conciseness or golfing ;)

$s=$n<0|-($n>0)

where $s sign is 1 if positive, -1 if negative, otherwise -0 or +0 which is still 0
up
-7
krees
8 years ago
You can also do this:
<?php
$sign
= min(1, max(-1, $a));
?>
up
-5
Andrew Martin
7 years ago
Another way for those without GMP:

<?php
function sign($number) {
    return
$number / abs($number ?: 1);
}
?>
up
-8
gri501r at yandex dot ru
7 years ago
May be it's bug :
     gmp_sign(1) returns 'false'

官方地址:https://www.php.net/manual/en/function.gmp-sign.php

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