(PHP 4 >= 4.0.4, PHP 5, PHP 7)
gmp_sign — Sign of number
aEither 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 int.
Returns 1 if a is positive,
-1 if a is negative,
and 0 if a is zero.
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