SunshinePHP Developer Conference 2015

gmp_sign

(PHP 4 >= 4.0.4, PHP 5)

gmp_signSign of number

说明

int gmp_sign ( GMP $a )

Checks the sign of a number.

参数

a

可以是一个 GMP 数据 resouce,或一个可以转换为数值的字符串。

返回值

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

范例

Example #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

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User Contributed Notes 4 notes

up
6
thomas at zilliox dot me
3 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
krees
6 months ago
You can also do this:
<?php
$sign
= min(1, max(-1, $a));
?>
up
0
Andrew Martin
17 days ago
Another way for those without GMP:

<?php
function sign($number) {
    return
$number / abs($number ?: 1);
}
?>
up
0
gri501r at yandex dot ru
1 month ago
May be it's bug :
     gmp_sign(1) returns 'false'
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