大数乘法

第1行：大数A
第2行：大数B
(A,B的长度?<=?1000，A,B?>=?0）

输出A?*?B

123456
234567

28958703552

#include <iostream>
#include <algorithm>
#include <string.h>
using namespace std;

char a[1000];
char b[1000];
char result[3000];

void fun(int m,int n)
{
	int len = 0;
	int pos = 0;

	memset(result,sizeof(result));
	for (int i = m-1; i >= 0; i--)
	{
		int d = pos;
		for (int j = n-1; j >= 0; j--)
		{
			int temp = a[i] * b[j];
			temp += result[d];
			result[d] = temp % 10;
			result[d+1] += temp / 10;
			d++;
		}
		pos++;
	}

	bool found = false;
	for (int i = m+n+1; i >= 0; i--)
	{
		if (result[i] != 0)
		{
			found = true;
			cout << (int)result[i];
		}
		else if (found)
		{
			cout << (int)result[i];
		}
	}
}

int main()
{
	cin >> a >> b;
	int m = strlen(a);
	int n = strlen(b);
	for (int i = 0; i < m; i++)
	{
		a[i] -= '0';
	}

	for (int j = 0; j < n; j++)
	{
		b[j] -= '0';
	}
	fun(m,n);

    return 0;
}