gmp_sign()

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

Sign of number

说明

Checks the sign of a number.

参数

Either a GMP number resource in PHP 5.5 and earlier, a GMP object in PHP 5.6 and later, or a numeric string provided that it is possible to convert the latter to an integer.

返回值

Returns 1 if$ais positive,-1 if$ais negative, and 0 if$ais zero.

范例

gmp_sign() example

以上例程会输出：

1
-1
0

参见

• gmp_abs()Absolute value
• abs()绝对值

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

Thomas.

Using a spaceship in PHP7: 

Just
$sign = ($a==0 ?0 :$a/abs($a));

For conciseness or golfing ;)
$s=$n0)
where $s sign is 1 if positive, -1 if negative, otherwise -0 or +0 which is still 0

You can also do this: 

Another way for those without GMP: 

May be it's bug :
   gmp_sign(1) returns 'false'

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