gmp_sign

(PHP 4 >= 4.0.4, PHP 5)

gmp_signSign of number

Description

int gmp_sign ( GMP $a )

Checks the sign of a number.

Parameters

a

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 a number.

Return Values

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

Examples

Example #1 gmp_sign() example

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

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

// zero
echo gmp_sign("0") . "\n";
?>

The above example will output:

1
-1
0

See Also

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User Contributed Notes 2 notes

up
5
thomas at zilliox dot me
2 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
3 months ago
You can also do this:
<?php
$sign
= min(1, max(-1, $a));
?>
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