先开启gmp扩展

<?php
// 普通整数计算
$a = 12345678901234567890;
$b = 98765432109876543210;
//不用gmp
$result_normal = $a * $b;
echo "普通整数乘积： " . $result_normal . "\n";

// 使用GMP扩展计算
$a_gmp = gmp_init("12345678901234567890");
$b_gmp = gmp_init("98765432109876543210");
//乘法计算
$result_gmp = gmp_mul($a_gmp, $b_gmp);
//输出结果
echo "GMP整数乘积： " . gmp_strval($result_gmp) . "\n";