这个库支持100000位数的加（+）减（-）乘（*）运算

语言：C++11及以上

#include <bits/stdc++.h>
using namespace std;
const unsigned int SIZE = 1e5;

class large
{
	public:
		bool if_positive;
		short value[SIZE];//value[0]表示位数,value[1]是个位,倒序录入
		void reset()
		{
			if_positive = true;
			memset(value,0,sizeof(value));
		}
		void get_abs() {if_positive = true;}
		void get_back() {if_positive = (if_positive)?false:true;}
		void times10()
		{
			int len = value[0];
			value[0]++;
			for(int i = len;i >= 1;i--)
			{
				value[i + 1] = value[i];
			}
			value[1] = 0;
		}
		void timek10(int k)
		{
			while(k--) times10();
		}
};

large add(large a,large b)
{
	large result;
	result.reset();
	int len = max(a.value[0],b.value[0]);
	result.value[0] = len;
	for(int i = 1;i <= len;i++)
	{
		int carry = a.value[i] + b.value[i];
		result.value[i] = carry % 10;
		carry /= 10;
		result.value[i + 1] += carry;
	}
	if(result.value[len + 1] > 0) result.value[0]++;
	return result;
}

large sub(large a,large b)
{
	large result;
	result.reset();
	int len = max(a.value[0],b.value[0]);
	for(int i = 1;i <= len;i++)
	{
		signed int carry = a.value[i] - b.value[i];
		if(carry < 0)
		{
			carry += 10;
			result.value[i + 1]--;
		}
		result.value[i] = carry;
	}
	if(result.value[len + 1] != 0) result.value[0]++;
	if(result.value[result.value[0]] < 0) result.if_positive = false;
	result.value[result.value[0]] = abs(result.value[result.value[0]]);
	return result;
}

large operator+(large a,large b)
{
	large result;
	result.reset();
	if(a.if_positive == b.if_positive)
	{
		result = add(a,b);
		result.if_positive = a.if_positive;
	}
	else
	{
		if(a.if_positive == true) result = sub(a,b);
		else result = sub(b,a);
	}
	return result;
}

large operator-(large a,large b)
{
	b.get_back();
	return a + b;
}

large string_to_large(string input)
{
	large result;
	if(input[0] == '-')
	{
		result.if_positive = false;
		input.erase(0,1);
	} 
	else if(input[0] == '+')
	{
		result.if_positive = true;
		input.erase(0,1);
	}
	else if(input[0] >= '0' && input[0] <= '9') result.if_positive = true;
	else
	{
		printf("Input Error");
		exit(0);
	}
	int len = input.size();
	for(int i = 0;i < len;i++)
	{
		result.value[len - i] = input[i];
	}
	return result;
}

string large_to_string(large output)
{
	int len = output.value[0];
	string result = "";
	for(int i = len;i >= 1;i--)
	{
		result += (char)(output.value[i] + '0');
	}
	return result;
}

void output_large(large out,bool front_enter,bool end_enter)
{
	string ans = large_to_string(out);
	if(front_enter) printf("\n");
	printf("%s",ans);
	if(end_enter) printf("\n");
}

large int_mul(large x,int y)
{
	large result;
	int len = x.value[0];
	int cur;
	for(int i = 1;i <= len;i++)
	{
		int ans = x.value[i] * y;
		cur = ans / 10; ans %= 10;
		result.value[i] = ans;
		result.value[i + 1] += cur;
	}
	result.value[0] = len;
	if(cur > 0) result.value[0]++;
	return result;
}

large mul(large a,large b)
{
	large ans;ans.reset();
	int len = a.value[0];
	for(int i = 1;i <= len;i++)
	{
		large cur = int_mul(b,a.value[i]);
		cur.timek10(i - 1);
		ans = ans + cur;
	}
	if(ans.value[ans.value[0] + 1] > 0) ans.value[0]++;
	return ans;
}

large operator*(large a,large b)
{
	large result;
	result = mul(a,b);
	result.if_positive = (a.if_positive == b.if_positive);
	return result;
}

large input_large()
{
	string s0;
	scanf("%s",&s0);
	return string_to_large(s0);
}