本文共 7673 字，大约阅读时间需要 25 分钟。

晚上加班的时候，策划一直在耳边念叨数值的事儿。有些心烦意乱，顺口吐槽到，不如把数值运算丢给服务器人员去算。

哪知策划立马就说，这不行，他们原来服务器进行六十多位的运算时候，服务器炸了。

一说这个我就不乐意了，正好前端时间写了个超大数运算的方法，拿来检测下。

var _nu = "83497893246298346827346872346982360823579357623984623957438574309580293583209572309857846982364932784687236478921740172340912784901274879216478916298461298437612984316712984761298471298471284798124791284782146871324617892461928746981723647438926478321740912374809128740128409217844321462141912849021834274623784631728461782461728";        var _f = "543897489324789234723884709284201480924788903275498327";        Debug.Log(LargeNumberCalculator.BigDatenumMulitfy(_nu, _f));

运算结果如图所示：

45414294500570946232766941981487532736101951529219837603814751565682140750606060305830153788739377945894441114448047125337713342779005019904853971980122004902613506487483958423414305100219402340260863310057396394835279845410829944230707927439104713224781013599416389511098350559798301920310589352886075269035259304696264356729808295144044599752214530030747527087148415956028005529056

大致验算下，位数7*8=56是正确的。具体的数换个计算方式一样，说明应该是正确的。

再换个数计算：

var _nu = "83497893246298346827346872346982360823579357623984623957438574309580293583209572309857846982364932784687236478921740172340912784901274879216478916298461298437612984316712984761298471298471284798124791284782146871324617892461928746981723647438926478321740912374809128740128409217844321462141912849021834274623784631728461782461728";        var _f = "7000000000000000000";        Debug.Log(LargeNumberCalculator.BigDatenumMulitfy(_nu, _f));

结果为：

584485252724088427791428106428876525765055503367892367702070020167062055082467006169004928876554529492810655352452181206386389494308924154515352414089229089063290890216990893329089299089298993586873538993475028099272325247233501228872065532072485348252186386623663901180898864524910250234993389943152839922366492422099232477232096000000000000000000

首位运算大致没错，耗时不到几毫秒，起码不会蹦。

这个梗可真是：我曾在极度愤怒的情况下，完成几百位的乘法运算。

代码用的是之前写的天文级别运算方法，按位去计算。不过其实C#是提供有个BigInteger类来处理的。这里公开下关于BigInteger部分的源码：

using System.Collections;using System.Collections.Generic;using System.Numerics;using UnityEngine;/// 
/// 大数计算器/// 
public class LargeNumberCalculator{    /// 
    /// 大数比较    /// 
    public static bool BigDateCompare(string _st1, string _st2)    {        var _sA1 = _st1.Split('.');        var _sA2 = _st2.Split('.');        try        {            BigInteger _b1 = BigInteger.Parse(_sA1[0]);            BigInteger _b2 = BigInteger.Parse(_sA2[0]);            if (BigInteger.Compare(_b1, _b2) >= 0) return true;        }        catch        {        }        return false;    }    /// 
    /// 大数相加    /// 
     public static string BigDataPlus(string _st1, string _st2)    {        var _sA1 = _st1.Split('.');               var _sA2 = _st2.Split('.');        try        {            BigInteger _b1 = BigInteger.Parse(_sA1[0]);            BigInteger _b2 = BigInteger.Parse(_sA2[0]);            _b1 = BigInteger.Add(_b1, _b2);            var _num = 0f;            if (_sA1.Length > 1) _num += GetBigdateFloat(_sA1[1]);                         if (_sA2.Length > 1) _num += GetBigdateFloat(_sA2[1]);            _b1 = BigInteger.Add(_b1, (int)_num);            return GetFewBehind("" + _b1,_num);        }        catch        {        }        return _st1;    }    /// 
    /// 大数相减:只支持被减数大于减数    /// 
     public static string BigDataSUB(string _st1, string _st2)    {        var _sA1 = _st1.Split('.');        var _sA2 = _st2.Split('.');        try        {            BigInteger _b1 = BigInteger.Parse(_sA1[0]);            BigInteger _b2 = BigInteger.Parse(_sA2[0]);            if (BigInteger.Compare(_b1, _b2) < 0) return "0";            _b1 = BigInteger.Subtract(_b1, _b2);            var _num = 0f;            if (_sA1.Length > 1) _num += GetBigdateFloat(_sA1[1]);            if (_sA2.Length > 1)            {                //借一位相减                _b1 = BigInteger.Add(_b1, -1);                _num = _num + 1 - GetBigdateFloat(_sA2[1]);            }            _b1 = BigInteger.Add(_b1, (int)_num);            return GetFewBehind("" + _b1, _num);        }        catch        {        }        return _st1;    }    /// 
    /// 计算某位与一个数字相乘        /// 
    public static string BigDatenumMulitfy(string _s1, string _s2)    {        //Debug.Log("~~~~~~~~~~~~~"+_s1+"   "+_s2);        var _sA1 = _s1.Split('.');        var _sA2 = _s2.Split('.');        try        {            var _num = 1;            var _get1 = "" + _sA1[0];            var _get2 = "" + _sA2[0];                       if (_sA1.Length > 1)            {                _get1 +=  "" + GetBigdateIntToString(_sA1[1]);                //Debug.Log(_get1);                _num *= 1000;            }            if (_sA2.Length > 1)            {                _get2 += "" + GetBigdateIntToString(_sA2[1]);                //Debug.Log(_get2);                _num *= 1000;            }            BigInteger _b1 = BigInteger.Parse(_get1);            BigInteger _b2 = BigInteger.Parse(_get2);            //Debug.Log(_b1 + "   " + _b2);            _b1 = BigInteger.Multiply(_b1, _b2);            //Debug.Log(_b1 + "   " + _num);            BigInteger _remainder = 0;            _b1 = BigInteger.DivRem(_b1, _num, out _remainder);            //Debug.Log("..." + _b1);            //Debug.Log(BigDateRounding(GetStrForBigdate("" + _remainder, _num)) + "   " + GetStrForBigdate("" + _remainder, _num));            if (_remainder > 0) return _b1 + "." + BigDateRounding(GetStrForBigdate("" + _remainder, _num));            return ""+_b1;                                }        catch        {        }        return _s1;    }    /// 
    /// 大数与float相乘，得出一个大数    /// 
    public static string BigDatenumMulitfy(string _str1, float _f2)    {       return BigDatenumMulitfy(_str1, _f2.ToString());    }    /// 
    /// float与float相乘，得出一个大数    /// 
    public static string BigDatenumMulitfy(float _f1, float _f2)    {        return BigDatenumMulitfy(_f1.ToString(), _f2);    }    /// 
    /// 获得只包含前三位的float值    /// 
    private static float GetBigdateFloat(string _str)    {        var _arr = _str.ToCharArray();        var _zero = "0.";        for (var _i = 0; _i < 3; _i++)        {            if (_i < _arr.Length) _zero += _arr[_i];        }        return float.Parse(_zero);    }    private static string GetBigdateIntToString(string _str)    {        var _arr = _str.ToCharArray();        var _zero = "";        for (var _i = 0; _i < 3; _i++)        {            if (_i < _arr.Length) _zero += _arr[_i];            else _zero += "0";        }        return /*int.Parse*/(_zero);    }    private static string GetStrForBigdate(string _str,int _bit)    {        _bit = _bit.ToString().Length - 1;        var _cNum = _bit - _str.Length;        for (var _i = 0; _i < _cNum; _i++) _str = "0" + _str;        _str = _str.Substring(0, 3);        return BigDateRounding(_str);    }    /// 
    /// 后去零    /// 
    private static string BigDateRounding(string _str)    {        for (var _i = _str.Length - 1; _i >= 0; _i--)        {            if (_str[_i] == '0')            {                _str = _str.Substring(0, _str.Length - 1);            }             else return _str;        }        return _str;    }    /// 
    /// 补全小数点后几位    /// 
    /// 
       private static string GetFewBehind(string _str, float _f)    {        var _arr = _f.ToString().Split('.');        if (_arr.Length > 1)        {            _str += ".";            var _theArr = _arr[1].ToCharArray();            for (var _i = 0; _i < 3; _i++)            {                if (_i < _theArr.Length) _str += _theArr[_i];            }            return _str;        }        else        {            return _str;        }        }}

这个思路也是拼接运算，其实放到java或者其他语言里面去，计算原理也是一样。

有需要的朋友，自己拿去。

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