Question

我需要使用长整数加上，现在我已经在字符串类型上创建了这个函数，但它要慢... 任何人都知道在字符串中计算加号的更好的解决方案吗？

这是我的功能：

 function math_plus($first, $second)
 {
 $first = strrev($first); $first_length = strlen($first);
 $second = strrev($second); $second_length = strlen($second);

 $result = "";
  if ($first_length > $second_length)
  {
  $big = $first; $big_length = $first_length;
  $small = $second; $small_length = $second_length;
  }
  else
  {
  $big = $second; $big_length = $second_length;
  $small = $first; $small_length = $first_length;
  }

 $memory_exists = false;
  for ($i=0;$i < $big_length;$i++)
  {
  $small_exists = ($i < $small_length)?true:false;

  $big_value = (int) substr($big, $i, 1);
  $value = $big_value;

   if ($small_exists)
   {
   $small_value = (int) substr($small, $i, 1);
   $value += $small_value;
   }
   if ($memory_exists){$value++;$memory_exists = false;}
   if ($value >= 10){$value -= 10; $memory_exists = true;}

  $result = $value . $result;
  }

  if ($memory_exists)
  {
  $result = "1" . $result;
  }

 return $result;
 }

 $first = "325436746798098576787634576587568764355645645654634645746657676543";
 $second = "325436746798098576787634576587568764355645645654634645746657676543";
 echo math_plus($first, $second);

Answer 1

使用BCMath：http://uk3.php.net/manual/en/function.bcadd.php

bcadd("1.00000", "2.00000");

PHP加上字符串类型

1 个答案: