(PHP 4 >= 4.0.4, PHP 5)
gmp_perfect_square — Perfect square check
Check if a number is a perfect square.
The number being checked as a perfect square.
可以是一个 GMP 数据 resouce，或一个可以转换为数值的字符串。
Returns TRUE if a is a perfect square, FALSE otherwise.
Example #1 gmp_perfect_square() example 以上例程会输出：
<?php
// 3 * 3, perfect square
var_dump(gmp_perfect_square("9"));
// not a perfect square
var_dump(gmp_perfect_square("7"));
// 1234567890 * 1234567890, perfect square
var_dump(gmp_perfect_square("1524157875019052100"));
?>
bool(true)
bool(false)
bool(true)